6175M–ATARM–26-Oct-12
Features
•Incorporates the ARM7TDMI® ARM® Thumb® Processor
– High-performance 32-bit RISC Architecture
– High-density 16-bit Instruction Set
– Leader in MIPS/Watt
– EmbeddedICE™ In-circuit Emulation, Debug Communication Channel Support
•Internal High-speed Flash
– 512 Kbytes (SAM7S512) Organized in Two Contiguous Banks of 1024 Pages of 256
Bytes (Dual Plane)
– 256 Kbytes (SAM7S256) Organized in 1024 Pages of 256 Bytes (Single Plane)
– 128 Kbytes (SAM7S128) Organized in 512 Pages of 256 Bytes (Single Plane)
– 64 Kbytes (SAM7S64) Organized in 512 Pages of 128 Bytes (Single Plane)
– 32 Kbytes (SAM7S321/32) Organized in 256 Pages of 128 Bytes (Single Plane)
– 16 Kbytes (SAM7S161/16) Organized in 256 Pages of 64 Bytes (Single Plane)
– Single Cycle Access at Up to 30 MHz in Worst Case Conditions
– Prefetch Buffer Optimizing Thumb Instruction Execution at Maximum Speed
– Page Programming Time: 6 ms, Including Page Auto-erase, Full Erase Time: 15 ms
– 10,000 Write Cycles, 10-year Data Retention Capability, Sector Lock Capabilities, Flash
Security Bit
– Fast Flash Programming Interface for High Volume Production
•Internal High-speed SRAM, Single-cycle Access at Maximum Speed
– 64 Kbytes (SAM7S512/256)
– 32 Kbytes (SAM7S128)
– 16 Kbytes (SAM7S64)
– 8 Kbytes (SAM7S321/32)
– 4 Kbytes (SAM7S161/16)
•Memory Controller (MC)
– Embedded Flash Controller, Abort Status and Misalignment Detection
•Reset Controller (RSTC)
– Based on Power-on Reset and Low-power Factory-calibrated Brown-out Detector
– Provides External Reset Signal Shaping and Reset Source Status
•Clock Generator (CKGR)
– Low-power RC Oscillator, 3 to 20 MHz On-chip Oscillator and one PLL
•Power Management Controller (PMC)
– Software Power Optimization Capabilities, Including Slow Clock Mode (Down to 500
Hz) and Idle Mode
– Three Programmable External Clock Signals
•Advanced Interrupt Controller (AIC)
– Individually Maskable, Eight-level Priority, Vectored Interrupt Sources
– Two (SAM7S512/256/128/64/321/161) or One (SAM7S32/16) External Interrupt Source(s)
and One Fast Interrupt Source, Spurious Interrupt Protected
AT91SAM
ARM-based Flash MCU
SAM7S512 SAM7S256 SAM7S128 SAM7S64
SAM7S321 SAM7S32 SAM7S161 SAM7S16
2
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
•Debug Unit (DBGU)
– 2-wire UART and Support for Debug Communication Channel interrupt, Programmable ICE Access Prevention
– Mode for General Purpose 2-wire UART Serial Communication
•Periodic Interval Timer (PIT)
– 20-bit Programmable Counter plus 12-bit Interval Counter
•Windowed Watchdog (WDT)
– 12-bit key-protected Programmable Counter
– Provides Reset or Interrupt Signals to the System
– Counter May Be Stopped While the Processor is in Debug State or in Idle Mode
•Real-time Timer (RTT)
– 32-bit Free-running Counter with Alarm
– Runs Off the Internal RC Oscillator
•One Parallel Input/Output Controller (PIOA)
– Thirty-two (SAM7S512/256/128/64/321/161) or twenty-one (SAM7S32/16) Programmable I/O Lines Multiplexed with up to
Two Peripheral I/Os
– Input Change Interrupt Capability on Each I/O Line
– Individually Programmable Open-drain, Pull-up resistor and Synchronous Output
•Eleven (SAM7S512/256/128/64/321/161) or Nine (SAM7S32/16) Peripheral DMA Controller (PDC) Channels
•One USB 2.0 Full Speed (12 Mbits per Second) Device Port (Except for the SAM7S32/16).
– On-chip Transceiver, 328-byte Configurable Integrated FIFOs
•One Synchronous Serial Controller (SSC)
– Independent Clock and Frame Sync Signals for Each Receiver and Transmitter
– I²S Analog Interface Support, Time Division Multiplex Support
– High-speed Continuous Data Stream Capabilities with 32-bit Data Transfer
•Two (SAM7S512/256/128/64/321/161) or One (SAM7S32/16) Universal Synchronous/Asynchronous Receiver Transmitters
(USART)
– Individual Baud Rate Generator, IrDA® Infrared Modulation/Demodulation
– Support for ISO7816 T0/T1 Smart Card, Hardware Handshaking, RS485 Support
– Full Modem Line Support on USART1 (SAM7S512/256/128/64/321/161)
•One Master/Slave Serial Peripheral Interface (SPI)
– 8- to 16-bit Programmable Data Length, Four External Peripheral Chip Selects
•One Three-channel 16-bit Timer/Counter (TC)
– Three External Clock Input and Two Multi-purpose I/O Pins per Channel (SAM7S512/256/128/64/321/161)
– One External Clock Input and Two Multi-purpose I/O Pins for the first Two Channels Only (SAM7S32/16)
– Double PWM Generation, Capture/Waveform Mode, Up/Down Capability
•One Four-channel 16-bit PWM Controller (PWMC)
•One Two-wire Interface (TWI)
– Master Mode Support Only, All Two-wire Atmel EEPROMs and I2C Compatible Devices Supported
(SAM7S512/256/128/64/321/32)
– Master, Multi-Master and Slave Mode Support, All Two-wire Atmel EEPROMs and I2C Compatible Devices Supported
(SAM7S161/16)
•One 8-channel 10-bit Analog-to-Digital Converter, Four Channels Multiplexed with Digital I/Os
•SAM-BA™ Boot Assistant
– Default Boot program
– Interface with SAM-BA Graphic User Interface
•IEEE® 1149.1 JTAG Boundary Scan on All Digital Pins
•5V-tolerant I/Os, including Four High-current Drive I/O lines, Up to 16 mA Each (SAM7S161/16 I/Os Not 5V-tolerant)
•Power Supplies
– Embedded 1.8V Regulator, Drawing up to 100 mA for the Core and External Components
– 3.3V or 1.8V VDDIO I/O Lines Power Supply, Independent 3.3V VDDFLASH Flash Power Supply
– 1.8V VDDCORE Core Power Supply with Brown-out Detector
3
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
•Fully Static Operation: Up to 55 MHz at 1.65V and 85°C Worst Case Conditions
•Available in 64-lead LQFP Green or 64-pad QFN Green Package (SAM7S512/256/128/64/321/161) and 48-lead LQFP Green or
48-pad QFN Green Package (SAM7S32/16)
1. Description
Atmel’s SAM7S is a series of low pincount Flash microcontrollers based on the 32-bit ARM RISC processor. It fea-
tures a high-speed Flash and an SRAM, a large set of peripherals, including a USB 2.0 device (except for the
SAM7S32 and SAM7S16), and a complete set of system functions minimizing the number of external components.
The device is an ideal migration path for 8-bit microcontroller users looking for additional performance and
extended memory.
The embedded Flash memory can be programmed in-system via the JTAG-ICE interface or via a parallel interface
on a production programmer prior to mounting. Built-in lock bits and a security bit protect the firmware from acci-
dental overwrite and preserves its confidentiality.
The SAM7S Series system controller includes a reset controller capable of managing the power-on sequence of
the microcontroller and the complete system. Correct device operation can be monitored by a built-in brownout
detector and a watchdog running off an integrated RC oscillator.
The SAM7S Series are general-purpose microcontrollers. Their integrated USB Device port makes them ideal devices
for peripheral applications requiring connectivity to a PC or cellular phone. Their aggressive price point and high level of
integration pushes their scope of use far into the cost-sensitive, high-volume consumer market.
1.1 Configuration Summary of the SAM7S512, SAM7S256, SAM7S128, SAM7S64, SAM7S321,
SAM7S32, SAM7S161 and SAM7S16
The SAM7S512, SAM7S256, SAM7S128, SAM7S64, SAM7S321, SAM7S32, SAM7S161 and SAM7S16 differ in
memory size, peripheral set and package. Table 1-1 summarizes the configuration of the six devices.
Except for the SAM7S32/16, all other SAM7S devices are package and pinout compatible.
Notes: 1. Fractional Baud Rate.
2. Full modem line support on USART1.
3. Only two TC channels are accessible through the PIO.
Table 1-1. Configuration Summary
Device Flash TWI
Flash
Organization SRAM
USB
Device
Port USART
External
Interrupt
Source
PDC
Channels
TC
Channels
I/O 5V
Tolerant
I/O
Lines Package
SAM7S512 512 Kbytes Master dual plane 64 Kbytes 1 2(1) (2) 2113 Yes32
LQFP/
QFN 64
SAM7S256 256 Kbytes Master single plane 64 Kbytes 1 2(1) (2) 2113 Yes32
LQFP/
QFN 64
SAM7S128 128 Kbytes Master single plane 32 Kbytes 1 2(1) (2) 2113 Yes32
LQFP/
QFN 64
SAM7S64 64 Kbytes Master single plane 16 Kbytes 1 2(2) 2113 Yes32
LQFP/
QFN 64
SAM7S321 32 Kbytes Master single plane 8 Kbytes 1 2(2) 2113 Yes32
LQFP/
QFN 64
SAM7S32 32 Kbytes Master single plane 8 Kbytes not
present 11 9 3
(3) Yes 21 LQFP/
QFN 48
SAM7S161 16 Kbytes Master/
Slave single plane 4 Kbytes 1 2(2) 2113 No32LQFP
SAM7S16 16 Kbytes Master/
Slave single plane 4 Kbytes not
present 11 9 3
(3) No 21 LQFP/
QFN 48
4
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
2. Block Diagram
Figure 2-1. SAM7S512/256/128/64/321/161 Block Diagram
TDI
TDO
TMS
TCK
NRST
FIQ
IRQ0-IRQ1
PCK0-PCK2
PMC
Peripheral Bridge
Peripheral Data
Controller
AIC
PLL
RCOSC
SRAM
64/32/16/8/4 Kbytes
ARM7TDMI
Processor
ICE
JTAG
SCAN
JTAGSEL
PIOA
USART0
SSC
Timer Counter
RXD0
TXD0
SCK0
RTS0
CTS0
NPCS0
NPCS1
NPCS2
NPCS3
MISO
MOSI
SPCK
Flash
512/256/
128/64/32/16 Kbytes
Reset
Controller
DRXD
DTXD
TF
TK
TD
RD
RK
RF
TCLK0
TCLK1
TCLK2
TIOA0
TIOB0
TIOA1
TIOB1
TIOA2
TIOB2
Memory Controller
Abort
Status
Address
Decoder
Misalignment
Detection
PIO
PIO
APB
POR
Embedded
Flash
Controller
AD0
AD1
AD2
AD3
ADTRG
PLLRC
11 Channels
PDC
PDC
USART1
RXD1
TXD1
SCK1
RTS1
CTS1
DCD1
DSR1
DTR1
RI1
PDC
PDC
PDC
PDC
SPI
PDC
ADC
ADVREF
PDC
PDC
TC0
TC1
TC2
TWD
TWCK
TWI
OSC
XIN
XOUT
VDDIN
PWMC
PWM0
PWM1
PWM2
PWM3
1.8 V
Voltage
Regulator
USB Device
FIFO DDM
DDP
Transceiver
GND
VDDOUT
BOD
VDDCORE
VDDCORE
AD4
AD5
AD6
AD7
VDDFLASH
Fast Flash
Programming
Interface
ERASE
PIO
PGMD0-PGMD15
PGMNCMD
PGMEN0-PGMEN2
PGMRDY
PGMNVALID
PGMNOE
PGMCK
PGMM0-PGMM3
VDDIO
TST
DBGU
PDC
PDC
PIO
PIT
WDT
RTT
System Controller
VDDCORE
SAM-BA
ROM
5
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 2-2. SAM7S32/16 Block Diagram
ROM
TDI
TDO
TMS
TCK
NRST
FIQ
IRQ0
PCK0-PCK2
JTAGSEL
RXD0
TXD0
SCK0
RTS0
CTS0
NPCS0
NPCS1
NPCS2
NPCS3
MISO
MOSI
SPCK
DRXD
DTXD
TF
TK
TD
RD
RK
RF
TCLK0
TIOA0
TIOB0
TIOA1
TIOB1
AD0
AD1
AD2
AD3
ADTRG
PLLRC
9 Channels
ADVREF
TWD
TWCK
XIN
XOUT
VDDIN
PWM0
PWM1
PWM2
PWM3
GND
VDDOUT
VDDCORE
VDDCORE
AD4
AD5
AD6
AD7
VDDFLASH
ERASE
PGMD0-PGMD7
PGMNCMD
PGMEN0-PGMEN2
PGMRDY
PGMNVALID
PGMNOE
PGMCK
PGMM0-PGMM3
VDDIO
TST
VDDCORE
SRAM
8/4 Kbytes
ARM7TDMI
Processor
Flash
32/16 Kbytes
APB
SAM-BA
PMC
Peripheral Bridge
Peripheral DMA
Controller
AIC
PLL
RCOSC
ICE
JTAG
SCAN
PIOA
USART0
SSC
Timer Counter
Reset
Controller
Memory Controller
Abort
Status
Address
Decoder
Misalignment
Detection
PIO
PIO
POR
Embedded
Flash
Controller
PDC
PDC
PDC
PDC
SPI
PDC
ADC
PDC
PDC
TC0
TC1
TC2
TWI
OSC
PWMC
1.8 V
Voltage
Regulator
BOD
Fast Flash
Programming
Interface
PIO
DBGU
PDC
PDC
PIO
PIT
WDT
RTT
System Controller
6
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
3. Signal Description
Table 3-1. Signal Description List
Signal Name Function Type
Active
Level Comments
Power
VDDIN Voltage and ADC Regulator Power Supply
Input Power 3.0 to 3.6V
VDDOUT Voltage Regulator Output Power 1.85V nominal
VDDFLASH Flash Power Supply Power 3.0V to 3.6V
VDDIO I/O Lines Power Supply Power 3.0V to 3.6V or 1.65V to 1.95V
VDDCORE Core Power Supply Power 1.65V to 1.95V
VDDPLL PLL Power 1.65V to 1.95V
GND Ground Ground
Clocks, Oscillators and PLLs
XIN Main Oscillator Input Input
XOUT Main Oscillator Output Output
PLLRC PLL Filter Input
PCK0 - PCK2 Programmable Clock Output Output
ICE and JTAG
TCK Test Clock Input No pull-up resistor
TDI Test Data In Input No pull-up resistor
TDO Test Data Out Output
TMS Test Mode Select Input No pull-up resistor
JTAGSEL JTAG Selection Input Pull-down resistor(1)
Flash Memory
ERASE Flash and NVM Configuration Bits Erase
Command Input High Pull-down resistor(1)
Reset/Test
NRST Microcontroller Reset I/O Low Open-drain with pull-Up resistor
TST Test Mode Select Input High Pull-down resistor(1)
Debug Unit
DRXD Debug Receive Data Input
DTXD Debug Transmit Data Output
AIC
IRQ0 - IRQ1 External Interrupt Inputs Input IRQ1 not present on SAM7S32/16
FIQ Fast Interrupt Input Input
PIO
PA0 - PA31 Parallel IO Controller A I/O Pulled-up input at reset
PA0 - PA20 only on SAM7S32/16
7
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
USB Device Port
DDM USB Device Port Data - Analog not present on SAM7S32/16
DDP USB Device Port Data + Analog not present on SAM7S32/16
USART
SCK0 - SCK1 Serial Clock I/O SCK1 not present on SAM7S32/16
TXD0 - TXD1 Transmit Data I/O TXD1 not present on SAM7S32/16
RXD0 - RXD1 Receive Data Input RXD1 not present on SAM7S32/16
RTS0 - RTS1 Request To Send Output RTS1 not present on SAM7S32/16
CTS0 - CTS1 Clear To Send Input CTS1 not present on SAM7S32/16
DCD1 Data Carrier Detect Input not present on SAM7S32/16
DTR1 Data Terminal Ready Output not present on SAM7S32/16
DSR1 Data Set Ready Input not present on SAM7S32/16
RI1 Ring Indicator Input not present on SAM7S32/16
Synchronous Serial Controller
TD Transmit Data Output
RD Receive Data Input
TK Transmit Clock I/O
RK Receive Clock I/O
TF Transmit Frame Sync I/O
RF Receive Frame Sync I/O
Timer/Counter
TCLK0 - TCLK2 External Clock Inputs Input TCLK1 and TCLK2 not present on
SAM7S32/16
TIOA0 - TIOA2 I/O Line A I/O TIOA2 not present on SAM7S32/16
TIOB0 - TIOB2 I/O Line B I/O TIOB2 not present on SAM7S32/16
PWM Controller
PWM0 - PWM3 PWM Channels Output
SPI
MISO Master In Slave Out I/O
MOSI Master Out Slave In I/O
SPCK SPI Serial Clock I/O
NPCS0 SPI Peripheral Chip Select 0 I/O Low
NPCS1-NPCS3 SPI Peripheral Chip Select 1 to 3 Output Low
Table 3-1. Signal Description List (Continued)
Signal Name Function Type
Active
Level Comments
8
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Note: 1. Refer to Section 6. “I/O Lines Considerations” on page 14.
Two-Wire Interface
TWD Two-wire Serial Data I/O
TWCK Two-wire Serial Clock I/O
Analog-to-Digital Converter
AD0-AD3 Analog Inputs Analog Digital pulled-up inputs at reset
AD4-AD7 Analog Inputs Analog Analog Inputs
ADTRG ADC Trigger Input
ADVREF ADC Reference Analog
Fast Flash Programming Interface
PGMEN0-PGMEN2 Programming Enabling Input
PGMM0-PGMM3 Programming Mode Input
PGMD0-PGMD15 Programming Data I/O PGMD0-PGMD7 only on SAM7S32/16
PGMRDY Programming Ready Output High
PGMNVALID Data Direction Output Low
PGMNOE Programming Read Input Low
PGMCK Programming Clock Input
PGMNCMD Programming Command Input Low
Table 3-1. Signal Description List (Continued)
Signal Name Function Type
Active
Level Comments
9
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
4. Package and Pinout
The SAM7S512/256/128/64/321 are available in a 64-lead LQFP or 64-pad QFN package.
The SAM7S161 is available in a 64-Lead LQFP package.
The SAM7S32/16 are available in a 48-lead LQFP or 48-pad QFN package.
4.1 64-lead LQFP and 64-pad QFN Package Outlines
Figure 4-1 and Figure 4-2 show the orientation of the 64-lead LQFP and the 64-pad QFN package. A detailed
mechanical description is given in the section Mechanical Characteristics of the full datasheet.
Figure 4-1. 64-lead LQFP Package (Top View)
Figure 4-2. 64-pad QFN Package (Top View)
116
17
32
3348
49
64
3348
161
49
64
32
17
10
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
4.2 64-lead LQFP and 64-pad QFN Pinout
Note: 1. The bottom pad of the QFN package must be connected to ground.
Table 4-1. SAM7S512/256/128/64/321/161 Pinout(1)
1 ADVREF 17 GND 33 TDI 49 TDO
2 GND 18 VDDIO 34 PA6/PGMNOE 50 JTAGSEL
3 AD4 19 PA16/PGMD4 35 PA5/PGMRDY 51 TMS
4 AD5 20 PA15/PGMD3 36 PA4/PGMNCMD 52 PA31
5 AD6 21 PA14/PGMD2 37 PA27/PGMD15 53 TCK
6 AD7 22 PA13/PGMD1 38 PA28 54 VDDCORE
7 VDDIN 23 PA24/PGMD12 39 NRST 55 ERASE
8 VDDOUT 24 VDDCORE 40 TST 56 DDM
9 PA17/PGMD5/AD0 25 PA25/PGMD13 41 PA29 57 DDP
10 PA18/PGMD6/AD1 26 PA26/PGMD14 42 PA30 58 VDDIO
11 PA21/PGMD9 27 PA12/PGMD0 43 PA3 59 VDDFLASH
12 VDDCORE 28 PA11/PGMM3 44 PA2/PGMEN2 60 GND
13 PA19/PGMD7/AD2 29 PA10/PGMM2 45 VDDIO 61 XOUT
14 PA22/PGMD10 30 PA9/PGMM1 46 GND 62 XIN/PGMCK
15 PA23/PGMD11 31 PA8/PGMM0 47 PA1/PGMEN1 63 PLLRC
16 PA20/PGMD8/AD3 32 PA7/PGMNVALID 48 PA0/PGMEN0 64 VDDPLL
11
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
4.3 48-lead LQFP and 48-pad QFN Package Outlines
Figure 4-3 and Figure 4-4 show the orientation of the 48-lead LQFP and the 48-pad QFN package. A detailed
mechanical description is given in the section Mechanical Characteristics of the full datasheet.
Figure 4-3. 48-lead LQFP Package (Top View)
Figure 4-4. 48-pad QFN Package (Top View)
4.4 48-lead LQFP and 48-pad QFN Pinout
Note: 1. The bottom pad of the QFN package must be connected to ground.
112
13
24
2536
37
48
2536
121
37
48
24
13
Table 4-2. SAM7S32/16 Pinout(1)
1 ADVREF 13 VDDIO 25 TDI 37 TDO
2 GND 14 PA16/PGMD4 26 PA6/PGMNOE 38 JTAGSEL
3 AD4 15 PA15/PGMD3 27 PA5/PGMRDY 39 TMS
4 AD5 16 PA14/PGMD2 28 PA4/PGMNCMD 40 TCK
5 AD6 17 PA13/PGMD1 29 NRST 41 VDDCORE
6 AD7 18 VDDCORE 30 TST 42 ERASE
7 VDDIN 19 PA12/PGMD0 31 PA3 43 VDDFLASH
8 VDDOUT 20 PA11/PGMM3 32 PA2/PGMEN2 44 GND
9 PA17/PGMD5/AD0 21 PA10/PGMM2 33 VDDIO 45 XOUT
10 PA18/PGMD6/AD1 22 PA9/PGMM1 34 GND 46 XIN/PGMCK
11 PA19/PGMD7/AD2 23 PA8/PGMM0 35 PA1/PGMEN1 47 PLLRC
12 PA20/AD3 24 PA7/PGMNVALID 36 PA0/PGMEN0 48 VDDPLL
12
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
5. Power Considerations
5.1 Power Supplies
The SAM7S Series has six types of power supply pins and integrates a voltage regulator, allowing the device to be
supplied with only one voltage. The six power supply pin types are:
zVDDIN pin. It powers the voltage regulator and the ADC; voltage ranges from 3.0V to 3.6V, 3.3V nominal.
zVDDOUT pin. It is the output of the 1.8V voltage regulator.
zVDDIO pin. It powers the I/O lines and the USB transceivers; dual voltage range is supported. Ranges from 3.0V
to 3.6V, 3.3V nominal or from 1.65V to 1.95V, 1.8V nominal. Note that supplying less than 3.0V to VDDIO prevents
any use of the USB transceivers.
zVDDFLASH pin. It powers a part of the Flash and is required for the Flash to operate correctly; voltage ranges
from 3.0V to 3.6V, 3.3V nominal.
zVDDCORE pins. They power the logic of the device; voltage ranges from 1.65V to 1.95V, 1.8V typical. It can be
connected to the VDDOUT pin with decoupling capacitor. VDDCORE is required for the device, including its
embedded Flash, to operate correctly.
During startup, core supply voltage (VDDCORE) slope must be superior or equal to 6V/ms.
zVDDPLL pin. It powers the oscillator and the PLL. It can be connected directly to the VDDOUT pin.
No separate ground pins are provided for the different power supplies. Only GND pins are provided and should be
connected as shortly as possible to the system ground plane.
In order to decrease current consumption, if the voltage regulator and the ADC are not used, VDDIN, ADVREF, AD4,
AD5, AD6 and AD7 should be connected to GND. In this case VDDOUT should be left unconnected.
5.2 Power Consumption
The SAM7S Series has a static current of less than 60 µA on VDDCORE at 25°C, including the RC oscillator, the voltage
regulator and the power-on reset. When the brown-out detector is activated, 20 µA static current is added.
The dynamic power consumption on VDDCORE is less than 50 mA at full speed when running out of the Flash. Under
the same conditions, the power consumption on VDDFLASH does not exceed 10 mA.
5.3 Voltage Regulator
The SAM7S Series embeds a voltage regulator that is managed by the System Controller.
In Normal Mode, the voltage regulator consumes less than 100 µA static current and draws 100 mA of output current.
The voltage regulator also has a Low-power Mode. In this mode, it consumes less than 25 µA static current and draws 1
mA of output current.
Adequate output supply decoupling is mandatory for VDDOUT to reduce ripple and avoid oscillations. The best way to
achieve this is to use two capacitors in parallel: one external 470 pF (or 1 nF) NPO capacitor must be connected between
VDDOUT and GND as close to the chip as possible. One external 2.2 µF (or 3.3 µF) X7R capacitor must be connected
between VDDOUT and GND.
Adequate input supply decoupling is mandatory for VDDIN in order to improve startup stability and reduce source voltage
drop. The input decoupling capacitor should be placed close to the chip. For example, two capacitors can be used in
parallel: 100 nF NPO and 4.7 µF X7R.
5.4 Typical Powering Schematics
The SAM7S Series supports a 3.3V single supply mode. The internal regulator is connected to the 3.3V source and its
output feeds VDDCORE and the VDDPLL. Figure 5-1 shows the power schematics to be used for USB bus-powered
systems.
13
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 5-1. 3.3V System Single Power Supply Schematic
Power Source
ranges
from 4.5V (USB)
to 18V
3.3V
VDDIN
Voltage
Regulator
VDDOUT
VDDIO
DC/DC Converter
VDDCORE
VDDFLASH
VDDPLL
14
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
6. I/O Lines Considerations
6.1 JTAG Port Pins
TMS, TDI and TCK are schmitt trigger inputs. TMS and TCK are 5-V tolerant, TDI is not. TMS, TDI and TCK do not
integrate a pull-up resistor.
TDO is an output, driven at up to VDDIO, and has no pull-up resistor.
The JTAGSEL pin is used to select the JTAG boundary scan when asserted at a high level. The JTAGSEL pin integrates
a permanent pull-down resistor of about 15 kΩ to GND, so that it can be left unconnected for normal operations.
6.2 Test Pin
The TST pin is used for manufacturing test, fast programming mode or SAM-BA Boot Recovery of the SAM7S Series
when asserted high. The TST pin integrates a permanent pull-down resistor of about 15 kΩ to GND, so that it can be left
unconnected for normal operations.
To enter fast programming mode, the TST pin and the PA0 and PA1 pins should be tied high and PA2 tied to low.
To enter SAM-BA Boot Recovery, the TST pin and the PA0, PA1 and PA2 pins should be tied high for at least 10
seconds. Then a power cycle of the board is mandatory.
Driving the TST pin at a high level while PA0 or PA1 is driven at 0 leads to unpredictable results.
6.3 Reset Pin
The NRST pin is bidirectional with an open drain output buffer. It is handled by the on-chip reset controller and can be
driven low to provide a reset signal to the external components or asserted low externally to reset the microcontroller.
There is no constraint on the length of the reset pulse, and the reset controller can guarantee a minimum pulse length.
This allows connection of a simple push-button on the pin NRST as system user reset, and the use of the signal NRST to
reset all the components of the system.
The NRST pin integrates a permanent pull-up resistor to VDDIO.
6.4 ERASE Pin
The ERASE pin is used to re-initialize the Flash content and some of its NVM bits. It integrates a permanent pull-down
resistor of about 15 kΩ to GND, so that it can be left unconnected for normal operations.
6.5 PIO Controller A Lines
zAll the I/O lines PA0 to PA31on SAM7S512/256/128/64/321 (PA0 to PA20 on SAM7S32) are 5V-tolerant and all
integrate a programmable pull-up resistor.
zAll the I/O lines PA0 to PA31 on SAM7S161 (PA0 to PA20 on SAM7S16) are not 5V-tolerant and all integrate a
programmable pull-up resistor.
Programming of this pull-up resistor is performed independently for each I/O line through the PIO controllers.
5V-tolerant means that the I/O lines can drive voltage level according to VDDIO, but can be driven with a voltage of up to
5.5V. However, driving an I/O line with a voltage over VDDIO while the programmable pull-up resistor is enabled will
create a current path through the pull-up resistor from the I/O line to VDDIO. Care should be taken, in particular at reset,
as all the I/O lines default to input with the pull-up resistor enabled at reset.
6.6 I/O Line Drive Levels
The PIO lines PA0 to PA3 are high-drive current capable. Each of these I/O lines can drive up to 16 mA permanently.
The remaining I/O lines can draw only 8 mA.
However, the total current drawn by all the I/O lines cannot exceed 150 mA (100 mA for SAM7S32/16).
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7. Processor and Architecture
7.1 ARM7TDMI Processor
zRISC processor based on ARMv4T Von Neumann architecture
zRuns at up to 55 MHz, providing 0.9 MIPS/MHz
zTwo instruction sets
zARM® high-performance 32-bit instruction set
zThumb® high code density 16-bit instruction set
zThree-stage pipeline architecture
zInstruction Fetch (F)
zInstruction Decode (D)
zExecute (E)
7.2 Debug and Test Features
zIntegrated EmbeddedICE™ (embedded in-circuit emulator)
zTwo watchpoint units
zTest access port accessible through a JTAG protocol
zDebug communication channel
zDebug Unit
zTwo-pin UART
zDebug communication channel interrupt handling
zChip ID Register
zIEEE1149.1 JTAG Boundary-scan on all digital pins
7.3 Memory Controller
zBus Arbiter
zHandles requests from the ARM7TDMI and the Peripheral DMA Controller
zAddress decoder provides selection signals for
zThree internal 1 Mbyte memory areas
zOne 256 Mbyte embedded peripheral area
zAbort Status Registers
zSource, Type and all parameters of the access leading to an abort are saved
zFacilitates debug by detection of bad pointers
zMisalignment Detector
zAlignment checking of all data accesses
zAbort generation in case of misalignment
zRemap Command
zRemaps the SRAM in place of the embedded non-volatile memory
zAllows handling of dynamic exception vectors
zEmbedded Flash Controller
zEmbedded Flash interface, up to three programmable wait states
zPrefetch buffer, buffering and anticipating the 16-bit requests, reducing the required wait states
zKey-protected program, erase and lock/unlock sequencer
zSingle command for erasing, programming and locking operations
zInterrupt generation in case of forbidden operation
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7.4 Peripheral DMA Controller
zHandles data transfer between peripherals and memories
zEleven channels: SAM7S512/256/128/64/321/161
zNine channels: SAM7S32/16
zTwo for each USART
zTwo for the Debug Unit
zTwo for the Serial Synchronous Controller
zTwo for the Serial Peripheral Interface
zOne for the Analog-to-digital Converter
zLow bus arbitration overhead
zOne Master Clock cycle needed for a transfer from memory to peripheral
zTwo Master Clock cycles needed for a transfer from peripheral to memory
zNext Pointer management for reducing interrupt latency requirements
zPeripheral DMA Controller (PDC) priority is as follows (from the highest priority to the lowest):
Receive DBGU
Receive USART0
Receive USART1
Receive SSC
Receive ADC
Receive SPI
Transmit DBGU
Transmit USART0
Transmit USART1
Transmit SSC
Transmit SPI
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8. Memories
8.1 SAM7S512
z512 Kbytes of Flash Memory, dual plane
z2 contiguous banks of 1024 pages of 256 bytes
zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z32 lock bits, protecting 32 sectors of 64 pages
zProtection Mode to secure contents of the Flash
z64 Kbytes of Fast SRAM
zSingle-cycle access at full speed
8.2 SAM7S256
z256 Kbytes of Flash Memory, single plane
z1024 pages of 256 bytes
zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z16 lock bits, protecting 16 sectors of 64 pages
zProtection Mode to secure contents of the Flash
z64 Kbytes of Fast SRAM
zSingle-cycle access at full speed
8.3 SAM7S128
z128 Kbytes of Flash Memory, single plane
z512 pages of 256 bytes
zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z8 lock bits, protecting 8 sectors of 64 pages
zProtection Mode to secure contents of the Flash
z32 Kbytes of Fast SRAM
zSingle-cycle access at full speed
8.4 SAM7S64
z64 Kbytes of Flash Memory, single plane
z512 pages of 128 bytes
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zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z16 lock bits, protecting 16 sectors of 32 pages
zProtection Mode to secure contents of the Flash
z16 Kbytes of Fast SRAM
zSingle-cycle access at full speed
8.5 SAM7S321/32
z32 Kbytes of Flash Memory, single plane
z256 pages of 128 bytes
zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z8 lock bits, protecting 8 sectors of 32 pages
zProtection Mode to secure contents of the Flash
z8 Kbytes of Fast SRAM
zSingle-cycle access at full speed
8.6 SAM7S161/16
z16 Kbytes of Flash Memory, single plane
z256 pages of 64 bytes
zFast access time, 30 MHz single-cycle access in Worst Case conditions
zPage programming time: 6 ms, including page auto-erase
zPage programming without auto-erase: 3 ms
zFull chip erase time: 15 ms
z10,000 write cycles, 10-year data retention capability
z8 lock bits, protecting 8 sectors of 32 pages
zProtection Mode to secure contents of the Flash
z4 Kbytes of Fast SRAM
zSingle-cycle access at full speed
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Figure 8-1. SAM7S512/256/128/64/321/32/161/16 Memory Mapping
0x1000 0000
0x0000 0000
0x0FFF FFFF
0xF000 0000
0xEFFF FFFF
0xFFFF FFFF
256M Bytes
256 MBytes
14 x 256 MBytes
3,584 MBytes
0x000F FFF
0x0010 0000
0x001F FFF
0x0020 0000
0x002F FFF
0x0030 0000
0x0000 0000
1 MBytes
1 MBytes
1 MBytes
253 MBytes
0xFFFA 0000
0xFFFA 3FFF
0xFFFA 4000
0xF000 0000
0xFFFB 8000
0xFFFC 0000
0xFFFC 3FFF
0xFFFC 4000
0xFFFC 7FFF
0xFFFD 4000
0xFFFD 7FFF
0xFFFD 3FFF
0xFFFD FFFF
0xFFFE 0000
0xFFFE 3FFF
0xFFFF EFFF
0xFFFE 4000
0xFFFF FFFF
0xFFFF F000
0xFFFB 4000
0xFFFB 7FFF
0xFFF9 FFFF
0xFFFC FFFF
0xFFFD 8000
0xFFFD BFFF
0xFFFC BFFF
0xFFFC C000
0xFFFB FFFF
0xFFFB C000
0xFFFB BFFF
0xFFFA FFFF
0xFFFB 0000
0xFFFB 3FFF
0xFFFD 0000
0xFFFD C000
0xFFFC 8000
16 Kbytes
(Reserved on
SAM7S32/16)
16 Kbytes
(Reserved on
SAM7S32/16)
16 Kbytes
16 Kbytes
16 Kbytes
16 Kbytes
16 Kbytes
16 Kbytes
16 Kbytes
0x0FFF FFFF
512 Bytes/
128 registers
512 Bytes/
128 registers
256 Bytes/
64 registers
16 Bytes/
4 registers
16 Bytes/
4 registers
16 Bytes/
4 registers
16 Bytes/
4 registers
256 Bytes/
64 registers
4 Bytes/
1 register
512 Bytes/
128 registers
0xFFFF F000
0xFFFF F200
0xFFFF F1FF
0xFFFF F3FF
0xFFFF FBFF
0xFFFF FCFF
0xFFFF FEFF
0xFFFF FFFF
0xFFFF F400
0xFFFF FC00
0xFFFF FD0F
0xFFFF FC2F
0xFFFF FC3F
0xFFFF FD4F
0xFFFF FC6F
0xFFFF F5FF
0xFFFF F600
0xFFFF FD00
0xFFFF FF00
0xFFFF FD20
0xFFFF FD30
0xFFFF FD40
0xFFFF FD60
0xFFFF FD70
Internal Memories
Undefined
(Abort)
(1) Can be Flash or SRAM
depending on REMAP.
Flash before Remap
SRAM after Remap
Internal Flash
Internal SRAM
Reserved
Address Memory Space
Internal Memory Mapping
Note:
TC0, TC1, TC2
USART0
USART1
PWMC
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
TWI
SSC
SPI
UDP
ADC
AIC
DBGU
PIOA
Reserved
PMC
MC
WDT
PIT
RTT
RSTC
VREG
Peripheral Mapping
System Controller Mapping
Internal Peripherals
Reserved
SYSC
Reserved
(1)
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8.7 Memory Mapping
8.7.1 Internal SRAM
zThe SAM7S512 embeds a high-speed 64-Kbyte SRAM bank.
zThe SAM7S256 embeds a high-speed 64-Kbyte SRAM bank.
zThe SAM7S128 embeds a high-speed 32-Kbyte SRAM bank.
zThe SAM7S64 embeds a high-speed 16-Kbyte SRAM bank.
zThe SAM7S321 embeds a high-speed 8-Kbyte SRAM bank.
zThe SAM7S32 embeds a high-speed 8-Kbyte SRAM bank.
zThe SAM7S161 embeds a high-speed 4-Kbyte SRAM bank.
zThe SAM7S16 embeds a high-speed 4-Kbyte SRAM bank
After reset and until the Remap Command is performed, the SRAM is only accessible at address 0x0020 0000. After
Remap, the SRAM also becomes available at address 0x0.
8.7.2 Internal ROM
The SAM7S Series embeds an Internal ROM. The ROM contains the FFPI and the SAM-BA program.
The internal ROM is not mapped by default.
8.7.3 Internal Flash
zThe SAM7S512 features two contiguous banks (dual plane) of 256 Kbytes of Flash.
zThe SAM7S256 features one bank (single plane) of 256 Kbytes of Flash.
zThe SAM7S128 features one bank (single plane) of 128 Kbytes of Flash.
zThe SAM7S64 features one bank (single plane) of 64 Kbytes of Flash.
zThe SAM7S321/32 features one bank (single plane) of 32 Kbytes of Flash.
zThe SAM7S161/16 features one bank (single plane) of 16 Kbytes of Flash.
At any time, the Flash is mapped to address 0x0010 0000. It is also accessible at address 0x0 after the reset and before
the Remap Command.
Figure 8-2. Internal Memory Mapping
256 MBytes
Flash Before Remap
SRAM After Remap
Undefined Areas
(Abort)
0x000F FFFF
0x001F FFFF
0x002F FFFF
0x0FFF FFFF
1 MBytes
1 MBytes
1 MBytes
253 MBytes
Internal Flash
Internal SRAM
0x0000 0000
0x0010 0000
0x0020 0000
0x0030 0000
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SAM7S Series [DATASHEET]
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8.8 Embedded Flash
8.8.1 Flash Overview
zThe Flash of the SAM7S512 is organized in two banks (dual plane) of 1024 pages of 256 bytes. The 524,288 bytes
are organized in 32-bit words.
zThe Flash of the SAM7S256 is organized in 1024 pages (single plane) of 256 bytes. The 262,144 bytes are
organized in 32-bit words.
zThe Flash of the SAM7S128 is organized in 512 pages (single plane) of 256 bytes. The 131,072 bytes are
organized in 32-bit words.
zThe Flash of the SAM7S64 is organized in 512 pages (single plane) of 128 bytes. The 65,536 bytes are organized
in 32-bit words.
zThe Flash of the SAM7S321/32 is organized in 256 pages (single plane) of 128 bytes. The 32,768 bytes are
organized in 32-bit words.
zThe Flash of the SAM7S161/16 is organized in 256 pages (single plane) of 64 bytes. The 16,384 bytes are
organized in 32-bit words.
zThe Flash of the SAM7S512/256/128 contains a 256-byte write buffer, accessible through a 32-bit interface.
zThe Flash of the SAM7S64/321/32/161/16 contains a 128-byte write buffer, accessible through a 32-bit interface.
The Flash benefits from the integration of a power reset cell and from the brownout detector. This prevents code
corruption during power supply changes, even in the worst conditions.
When Flash is not used (read or write access), it is automatically placed into standby mode.
8.8.2 Embedded Flash Controller
The Embedded Flash Controller (EFC) manages accesses performed by the masters of the system. It enables reading
the Flash and writing the write buffer. It also contains a User Interface, mapped within the Memory Controller on the APB.
The User Interface allows:
zprogramming of the access parameters of the Flash (number of wait states, timings, etc.)
zstarting commands such as full erase, page erase, page program, NVM bit set, NVM bit clear, etc.
zgetting the end status of the last command
zgetting error status
zprogramming interrupts on the end of the last commands or on errors
The Embedded Flash Controller also provides a dual 32-bit prefetch buffer that optimizes 16-bit access to the Flash. This
is particularly efficient when the processor is running in Thumb mode.
Two EFCs are embedded in the SAM7S512 to control each bank of 256 Kbytes. Dual plane organization allows
concurrent Read and Program. Read from one memory plane may be performed even while program or erase functions
are being executed in the other memory plane.
One EFC is embedded in the SAM7S256/128/64/32/321/161/16 to control the single plane 256/128/64/32/16 Kbytes.
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8.8.3 Lock Regions
8.8.3.1 SAM7S512
Two Embedded Flash Controllers each manage 16 lock bits to protect 16 regions of the flash against inadvertent flash
erasing or programming commands. The SAM7S512 contains 32 lock regions and each lock region contains 64 pages of
256 bytes. Each lock region has a size of 16 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
The 16 NVM bits (or 32 NVM bits) are software programmable through the corresponding EFC User Interface. The
command “Set Lock Bit” enables the protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
8.8.3.2 SAM7S256
The Embedded Flash Controller manages 16 lock bits to protect 16 regions of the flash against inadvertent flash erasing
or programming commands. The SAM7S256 contains 16 lock regions and each lock region contains 64 pages of 256
bytes. Each lock region has a size of 16 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
The 16 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the
protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
8.8.3.3 SAM7S128
The Embedded Flash Controller manages 8 lock bits to protect 8 regions of the flash against inadvertent flash erasing or
programming commands. The SAM7S128 contains 8 lock regions and each lock region contains 64 pages of 256 bytes.
Each lock region has a size of 16 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
The 8 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the
protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
8.8.3.4 SAM7S64
The Embedded Flash Controller manages 16 lock bits to protect 16 regions of the flash against inadvertent flash erasing
or programming commands. The SAM7S64 contains 16 lock regions and each lock region contains 32 pages of 128
bytes. Each lock region has a size of 4 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
The 16 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the
protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
8.8.3.5 SAM7S321/32
The Embedded Flash Controller manages 8 lock bits to protect 8 regions of the flash against inadvertent flash erasing or
programming commands. The SAM7S321/32 contains 8 lock regions and each lock region contains 32 pages of 128
bytes. Each lock region has a size of 4 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
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SAM7S Series [DATASHEET]
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The 8 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the
protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
8.8.3.6 SAM7S161/16
The Embedded Flash Controller manages 8 lock bits to protect 8 regions of the flash against inadvertent flash erasing or
programming commands. The SAM7S161/16 contains 8 lock regions and each lock region contains 32 pages of 64
bytes. Each lock region has a size of 2 Kbytes.
If a locked-region’s erase or program command occurs, the command is aborted and the LOCKE bit in the MC_FSR
register rises and the interrupt line rises if the LOCKE bit has been written at 1 in the MC_FMR register.
The 8 NVM bits are software programmable through the EFC User Interface. The command “Set Lock Bit” enables the
protection. The command “Clear Lock Bit” unlocks the lock region.
Asserting the ERASE pin clears the lock bits, thus unlocking the entire Flash.
Table 8-1 summarizes the configuration of the eight devices.
8.8.4 Security Bit Feature
The SAM7S Series features a security bit, based on a specific NVM Bit. When the security is enabled, any access to the
Flash, either through the ICE interface or through the Fast Flash Programming Interface, is forbidden. This ensures the
confidentiality of the code programmed in the Flash.
This security bit can only be enabled, through the Command “Set Security Bit” of the EFC User Interface. Disabling the
security bit can only be achieved by asserting the ERASE pin at 1, and after a full flash erase is performed. When the
security bit is deactivated, all accesses to the flash are permitted.
It is important to note that the assertion of the ERASE pin should always be longer than 50 ms.
As the ERASE pin integrates a permanent pull-down, it can be left unconnected during normal operation. However, it is
safer to connect it directly to GND for the final application.
8.8.5 Non-volatile Brownout Detector Control
Two general purpose NVM (GPNVM) bits are used for controlling the brownout detector (BOD), so that even after a
power loss, the brownout detector operations remain in their state.
These two GPNVM bits can be cleared or set respectively through the commands “Clear General-purpose NVM Bit” and
“Set General-purpose NVM Bit” of the EFC User Interface.
zGPNVM Bit 0 is used as a brownout detector enable bit. Setting the GPNVM Bit 0 enables the BOD, clearing it
disables the BOD. Asserting ERASE clears the GPNVM Bit 0 and thus disables the brownout detector by default.
zThe GPNVM Bit 1 is used as a brownout reset enable signal for the reset controller. Setting the GPNVM Bit 1
enables the brownout reset when a brownout is detected, Clearing the GPNVM Bit 1 disables the brownout reset.
Asserting ERASE disables the brownout reset by default.
Table 8-1. Flash Configuration Summary
Device Number of Lock Bits Number of Pages in the Lock Region Page Size
SAM7S512 32 64 256 bytes
SAM7S256 16 64 256 bytes
SAM7S128 8 64 256 bytes
SAM7S64 16 32 128 bytes
SAM7S321/32 8 32 128 bytes
SAM7S161/16 8 32 64 bytes
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8.8.6 Calibration Bits
Eight NVM bits are used to calibrate the brownout detector and the voltage regulator. These bits are factory configured
and cannot be changed by the user. The ERASE pin has no effect on the calibration bits.
8.9 Fast Flash Programming Interface
The Fast Flash Programming Interface allows programming the device through either a serial JTAG interface or through
a multiplexed fully-handshaked parallel port. It allows gang-programming with market-standard industrial programmers.
The FFPI supports read, page program, page erase, full erase, lock, unlock and protect commands.
The Fast Flash Programming Interface is enabled and the Fast Programming Mode is entered when the TST pin and the
PA0 and PA1 pins are all tied high and PA2 is tied low.
8.10 SAM-BA Boot Assistant
The SAM-BA® Boot Recovery restores the SAM-BA Boot in the first two sectors of the on-chip Flash memory. The
SAM-BA Boot recovery is performed when the TST pin and the PA0, PA1 and PA2 pins are all tied high for 10 sec-
onds. Then, a power cycle of the board is mandatory.
The SAM-BA Boot Assistant is a default Boot Program that provides an easy way to program in situ the on-chip Flash
memory.
The SAM-BA Boot Assistant supports serial communication through the DBGU or through the USB Device Port. (The
SAM7S32/16 have no USB Device Port.)
zCommunication through the DBGU supports a wide range of crystals from 3 to 20 MHz via software auto-
detection.
zCommunication through the USB Device Port is limited to an 18.432 MHz crystal. (
The SAM-BA Boot provides an interface with SAM-BA Graphic User Interface (GUI).
9. System Controller
The System Controller manages all vital blocks of the microcontroller: interrupts, clocks, power, time, debug and reset.
The System Controller peripherals are all mapped to the highest 4 Kbytes of address space, between addresses 0xFFFF
F000 and 0xFFFF FFFF.
Figure 9-1 on page 26 and Figure 9-2 on page 27 show the product specific System Controller Block Diagrams.
Figure 8-1 on page 20 shows the mapping of the of the User Interface of the System Controller peripherals. Note that the
memory controller configuration user interface is also mapped within this address space.
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SAM7S Series [DATASHEET]
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Figure 9-1. System Controller Block Diagram (SAM7S512/256/128/64/321/161)
NRST
SLCK
Advanced
Interrupt
Controller
Real-Time
Timer
Periodic
Interval
Timer
Reset
Controller
PA0-PA31
periph_nreset
System Controller
Watchdog
Timer
wdt_fault
WDRPROC
PIO
Controller
POR
BOD
RCOSC
gpnvm[0]
cal
en
Power
Management
Controller
OSC
PLL
XIN
XOUT
PLLRC
MAINCK
PLLCK
pit_irq
MCK
proc_nreset
wdt_irq
periph_irq{2]
periph_nreset
periph_clk[2..14]
PCK
MCK
pmc_irq
UDPCK
nirq
nfiq
rtt_irq
Embedded
Peripherals
periph_clk[2]
pck[0-2]
in
out
enable
ARM7TDMI
SLCK
SLCK
irq0-irq1
fiq
irq0-irq1
fiq
periph_irq[4..14]
periph_irq[2..14]
int
int
periph_nreset
periph_clk[4..14]
Embedded
Flash
flash_poe
jtag_nreset
flash_poe
gpnvm[0..1]
flash_wrdis
flash_wrdis
proc_nreset
periph_nreset
dbgu_txd
dbgu_rxd
pit_irq
rtt_irq
dbgu_irq
pmc_irq
rstc_irq
wdt_irq
rstc_irq
SLCK
gpnvm[1]
Boundary Scan
TAP Controller
jtag_nreset
debug
PCK
debug
idle
debug
Memory
Controller
MCK
proc_nreset
bod_rst_en
proc_nreset
idle
Debug
Unit
dbgu_irq
MCK
dbgu_rxd
periph_nreset force_ntrst
dbgu_txd
USB Device
Port
UDPCK
periph_nreset
periph_clk[11]
periph_irq[11]
usb_suspend
usb_suspend
Voltage
Regulator
standby
Voltage
Regulator
Mode
Controller
security_bit
cal
power_on_reset
force_ntrst
cal
power_on_reset
power_on_reset
power_on_reset
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Figure 9-2. System Controller Block Diagram (SAM7S32/16)
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9.1 Reset Controller
The Reset Controller is based on a power-on reset cell and one brownout detector. It gives the status of the last reset,
indicating whether it is a power-up reset, a software reset, a user reset, a watchdog reset or a brownout reset. In addition,
it controls the internal resets and the NRST pin open-drain output. It allows to shape a signal on the NRST line,
guaranteeing that the length of the pulse meets any requirement.
Note that if NRST is used as a reset output signal for external devices during power-off, the brownout detector must be
activated.
9.1.1 Brownout Detector and Power-on Reset
The SAM7S Series embeds a brownout detection circuit and a power-on reset cell. Both are supplied with and monitor
VDDCORE. Both signals are provided to the Flash to prevent any code corruption during power-up or power-down
sequences or if brownouts occur on the VDDCORE power supply.
The power-on reset cell has a limited-accuracy threshold at around 1.5V. Its output remains low during power-up until
VDDCORE goes over this voltage level. This signal goes to the reset controller and allows a full re-initialization of the
device.
The brownout detector monitors the VDDCORE level during operation by comparing it to a fixed trigger level. It secures
system operations in the most difficult environments and prevents code corruption in case of brownout on the
VDDCORE.
Only VDDCORE is monitored.
When the brownout detector is enabled and VDDCORE decreases to a value below the trigger level (Vbot-, defined as
Vbot - hyst/2), the brownout output is immediately activated.
When VDDCORE increases above the trigger level (Vbot+, defined as Vbot + hyst/2), the reset is released. The
brownout detector only detects a drop if the voltage on VDDCORE stays below the threshold voltage for longer than
about 1µs.
The threshold voltage has a hysteresis of about 50 mV, to ensure spike free brownout detection. The typical value of the
brownout detector threshold is 1.68V with an accuracy of ± 2% and is factory calibrated.
The brownout detector is low-power, as it consumes less than 20 µA static current. However, it can be deactivated to
save its static current. In this case, it consumes less than 1µA. The deactivation is configured through the GPNVM bit 0 of
the Flash.
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9.2 Clock Generator
The Clock Generator embeds one low-power RC Oscillator, one Main Oscillator and one PLL with the following
characteristics:
zRC Oscillator ranges between 22 kHz and 42 kHz
zMain Oscillator frequency ranges between 3 and 20 MHz
zMain Oscillator can be bypassed
zPLL output ranges between 80 and 220 MHz
It provides SLCK, MAINCK and PLLCK.
Figure 9-3. Clock Generator Block Diagram
9.3 Power Management Controller
The Power Management Controller uses the Clock Generator outputs to provide:
zthe Processor Clock PCK
zthe Master Clock MCK
zthe USB Clock UDPCK (not present on SAM7S32/16)
zall the peripheral clocks, independently controllable
zthree programmable clock outputs
The Master Clock (MCK) is programmable from a few hundred Hz to the maximum operating frequency of the device.
The Processor Clock (PCK) switches off when entering processor idle mode, thus allowing reduced power consumption
while waiting for an interrupt.
Embedded
RC
Oscillator
Main
Oscillator
PLL and
Divider
Clock Generator
Power
Management
Controller
XIN
XOUT
PLLRC
Slow Clock
SLCK
Main Clock
MAINCK
PLL Clock
PLLCK
Control
Status
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Figure 9-4. Power Management Controller Block Diagram
9.4 Advanced Interrupt Controller
zControls the interrupt lines (nIRQ and nFIQ) of an ARM Processor
zIndividually maskable and vectored interrupt sources
zSource 0 is reserved for the Fast Interrupt Input (FIQ)
zSource 1 is reserved for system peripherals RTT, PIT, EFC, PMC, DBGU, etc.)
zOther sources control the peripheral interrupts or external interrupts
zProgrammable edge-triggered or level-sensitive internal sources
zProgrammable positive/negative edge-triggered or high/low level-sensitive external sources
z8-level Priority Controller
zDrives the normal interrupt of the processor
zHandles priority of the interrupt sources
zHigher priority interrupts can be served during service of lower priority interrupt
zVectoring
zOptimizes interrupt service routine branch and execution
zOne 32-bit vector register per interrupt source
zInterrupt vector register reads the corresponding current interrupt vector
zProtect Mode
zEasy debugging by preventing automatic operations
zFast Forcing
zPermits redirecting any interrupt source on the fast interrupt
zGeneral Interrupt Mask
zProvides processor synchronization on events without triggering an interrupt
MCK
periph_clk[2..14]
int
UDPCK
usb_suspend
SLCK
MAINCK
PLLCK
Prescaler
/1,/2,/4,...,/64
PCK
Processor
Clock
Controller
Idle Mode
Master Clock Controller
Peripherals
Clock Controller
ON/OFF
USB Clock Controller
ON/OFF
SLCK
MAINCK
PLLCK
Prescaler
/1,/2,/4,...,/64
Programmable Clock Controller
PLLCK Divider
/1,/2,/4
pck[0..2]
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9.5 Debug Unit
zComprises:
zOne two-pin UART
zOne Interface for the Debug Communication Channel (DCC) support
zOne set of Chip ID Registers
zOne Interface providing ICE Access Prevention
zTwo-pin UART
zImplemented features are compatible with the USART
zProgrammable Baud Rate Generator
zParity, Framing and Overrun Error
zAutomatic Echo, Local Loopback and Remote Loopback Channel Modes
zDebug Communication Channel Support
zOffers visibility of COMMRX and COMMTX signals from the ARM Processor
zChip ID Registers
zIdentification of the device revision, sizes of the embedded memories, set of peripherals
zChip ID is 0x270B0A40 for AT91SAM7S512 Rev A
zChip ID is 0x270B0A4F for AT91SAM7S512 Rev B
zChip ID is 0x270D0940 for AT91SAM7S256 Rev A
zChip ID is 0x270B0941 for AT91SAM7S256 Rev B
zChip ID is 0x270B0942 for AT91SAM7S256 Rev C
zChip ID is 0x270B0943 for AT91SAM7S256 Rev D
zChip ID is 0x270C0740 for AT91SAM7S128 Rev A
zChip ID is 0x270A0741 for AT91SAM7S128 Rev B
zChip ID is 0x270A0742 for AT91SAM7S128 Rev C
zChip ID is 0x270A0743 for AT91SAM7S128 Rev D
zChip ID is 0x27090540 for AT91SAM7S64 Rev A
zChip ID is 0x27090543 for AT91SAM7S64 Rev B
zChip ID is 0x27090544 for AT91SAM7S64 Rev C
zChip ID is 0x27080342 for AT91SAM7S321 Rev A
zChip ID is 0x27080340 for AT91SAM7S32 Rev A
zChip ID is 0x27080341 for AT91SAM7S32 Rev B
zChip ID is 0x27050241 for AT9SAM7S161 Rev A
zChip ID is 0x27050240 for AT91SAM7S16 Rev A
Note: Refer to the errata section of the datasheet for updates on chip ID.
9.6 Periodic Interval Timer
z20-bit programmable counter plus 12-bit interval counter
9.7 Watchdog Timer
z12-bit key-protected Programmable Counter running on prescaled SCLK
zProvides reset or interrupt signals to the system
zCounter may be stopped while the processor is in debug state or in idle mode
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9.8 Real-time Timer
z32-bit free-running counter with alarm running on prescaled SCLK
zProgrammable 16-bit prescaler for SLCK accuracy compensation
9.9 PIO Controller
zOne PIO Controller, controlling 32 I/O lines (21 for SAM7S32/16)
zFully programmable through set/clear registers
zMultiplexing of two peripheral functions per I/O line
zFor each I/O line (whether assigned to a peripheral or used as general-purpose I/O)
zInput change interrupt
zHalf a clock period glitch filter
zMulti-drive option enables driving in open drain
zProgrammable pull-up on each I/O line
zPin data status register, supplies visibility of the level on the pin at any time
zSynchronous output, provides Set and Clear of several I/O lines in a single write
9.10 Voltage Regulator Controller
The aim of this controller is to select the Power Mode of the Voltage Regulator between Normal Mode (bit 0 is cleared) or
Standby Mode (bit 0 is set).
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10. Peripherals
10.1 User Interface
The User Peripherals are mapped in the 256 MBytes of address space between 0xF000 0000 and 0xFFFF EFFF. Each
peripheral is allocated 16 Kbytes of address space.
A complete memory map is provided in Figure 8-1 on page 20.
10.2 Peripheral Identifiers
The SAM7S Series embeds a wide range of peripherals. Table 10-1 defines the Peripheral Identifiers of the
SAM7S512/256/128/64/321/161. Table 10-2 defines the Peripheral Identifiers of the SAM7S32/16. A peripheral identifier
is required for the control of the peripheral interrupt with the Advanced Interrupt Controller and for the control of the
peripheral clock with the Power Management Controller.
Note: 1. Setting SYSC and ADC bits in the clock set/clear registers of the PMC has no effect. The System Controller
is continuously clocked. The ADC clock is automatically started for the first conversion. In Sleep Mode the
ADC clock is automatically stopped after each conversion.
Note: 1. Setting SYSC and ADC bits in the clock set/clear registers of the PMC has no effect. The System Controller
is continuously clocked. The ADC clock is automatically started for the first conversion. In Sleep Mode the
ADC clock is automatically stopped after each conversion.
Table 10-1. Peripheral Identifiers (SAM7S512/256/128/64/321/161)
Peripheral
ID
Peripheral
Mnemonic
Peripheral
Name
External
Interrupt
0 AIC Advanced Interrupt Controller FIQ
1 SYSC(1) System
2 PIOA Parallel I/O Controller A
3 Reserved
4ADC
(1) Analog-to Digital Converter
5 SPI Serial Peripheral Interface
6 US0 USART 0
7 US1 USART 1
8 SSC Synchronous Serial Controller
9 TWI Two-wire Interface
10 PWMC PWM Controller
11 UDP USB Device Port
12 TC0 Timer/Counter 0
13 TC1 Timer/Counter 1
14 TC2 Timer/Counter 2
15 - 29 Reserved
30 AIC Advanced Interrupt Controller IRQ0
31 AIC Advanced Interrupt Controller IRQ1
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10.3 Peripheral Multiplexing on PIO Lines
The SAM7S Series features one PIO controller, PIOA, that multiplexes the I/O lines of the peripheral set.
PIO Controller A controls 32 lines (21 lines for SAM7S32/16). Each line can be assigned to one of two peripheral
functions, A or B. Some of them can also be multiplexed with the analog inputs of the ADC Controller.
Table 10-3, “Multiplexing on PIO Controller A (SAM7S512/256/128/64/321/161),” on page 35 and Table 10-4,
“Multiplexing on PIO Controller A (SAM7S32/16),” on page 36 define how the I/O lines of the peripherals A, B or the
analog inputs are multiplexed on the PIO Controller A. The two columns “Function” and “Comments” have been inserted
for the user’s own comments; they may be used to track how pins are defined in an application.
Note that some peripheral functions that are output only may be duplicated in the table.
All pins reset in their Parallel I/O lines function are configured as input with the programmable pull-up enabled, so that the
device is maintained in a static state as soon as a reset is detected.
Table 10-2. Peripheral Identifiers (SAM7S32/16)
Peripheral
ID
Peripheral
Mnemonic
Peripheral
Name
External
Interrupt
0 AIC Advanced Interrupt Controller FIQ
1 SYSC(1) System
2 PIOA Parallel I/O Controller A
3 Reserved
4ADC
(1) Analog-to Digital Converter
5 SPI Serial Peripheral Interface
6USUSART
7 Reserved
8 SSC Synchronous Serial Controller
9 TWI Two-wire Interface
10 PWMC PWM Controller
11 Reserved
12 TC0 Timer/Counter 0
13 TC1 Timer/Counter 1
14 TC2 Timer/Counter 2
15 - 29 Reserved
30 AIC Advanced Interrupt Controller IRQ0
31 Reserved
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10.4 PIO Controller A Multiplexing
Table 10-3. Multiplexing on PIO Controller A (SAM7S512/256/128/64/321/161)
PIO Controller A Application Usage
I/O Line Peripheral A Peripheral B Comments Function Comments
PA0 PWM0 TIOA0 High-Drive
PA1 PWM1 TIOB0 High-Drive
PA2 PWM2 SCK0 High-Drive
PA3 TWD NPCS3 High-Drive
PA4 TWCK TCLK0
PA5 RXD0 NPCS3
PA6 TXD0 PCK0
PA7 RTS0 PWM3
PA8 CTS0 ADTRG
PA9 DRXD NPCS1
PA10 DTXD NPCS2
PA11 NPCS0 PWM0
PA12 MISO PWM1
PA13 MOSI PWM2
PA14 SPCK PWM3
PA15 TF TIOA1
PA16 TK TIOB1
PA17 TD PCK1 AD0
PA18 RD PCK2 AD1
PA19 RK FIQ AD2
PA20 RF IRQ0 AD3
PA21 RXD1 PCK1
PA22 TXD1 NPCS3
PA23 SCK1 PWM0
PA24 RTS1 PWM1
PA25 CTS1 PWM2
PA26 DCD1 TIOA2
PA27 DTR1 TIOB2
PA28 DSR1 TCLK1
PA29 RI1 TCLK2
PA30 IRQ1 NPCS2
PA31 NPCS1 PCK2
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Table 10-4. Multiplexing on PIO Controller A (SAM7S32/16)
PIO Controller A Application Usage
I/O Line Peripheral A Peripheral B Comments Function Comments
PA0 PWM0 TIOA0 High-Drive
PA1 PWM1 TIOB0 High-Drive
PA2 PWM2 SCK0 High-Drive
PA3 TWD NPCS3 High-Drive
PA4 TWCK TCLK0
PA5 RXD0 NPCS3
PA6 TXD0 PCK0
PA7 RTS0 PWM3
PA8 CTS0 ADTRG
PA9 DRXD NPCS1
PA10 DTXD NPCS2
PA11 NPCS0 PWM0
PA12 MISO PWM1
PA13 MOSI PWM2
PA14 SPCK PWM3
PA15 TF TIOA1
PA16 TK TIOB1
PA17 TD PCK1 AD0
PA18 RD PCK2 AD1
PA19 RK FIQ AD2
PA20 RF IRQ0 AD3
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10.5 Serial Peripheral Interface
zSupports communication with external serial devices
zFour chip selects with external decoder allow communication with up to 15 peripherals
zSerial memories, such as DataFlash® and 3-wire EEPROMs
zSerial peripherals, such as ADCs, DACs, LCD Controllers, CAN Controllers and Sensors
zExternal co-processors
zMaster or slave serial peripheral bus interface
z8- to 16-bit programmable data length per chip select
zProgrammable phase and polarity per chip select
zProgrammable transfer delays between consecutive transfers and between clock and data per chip select
zProgrammable delay between consecutive transfers
zSelectable mode fault detection
zMaximum frequency at up to Master Clock
10.6 Two-wire Interface
zMaster Mode only (SAM7S512/256/128/64/321/32)
zMaster, Multi-Master and Slave Mode support (SAM7S161/16)
zGeneral Call supported in Slave Mode (SAM7S161/16)
zCompatibility with I2C compatible devices (refer to the TWI sections of the datasheet)
zOne, two or three bytes internal address registers for easy Serial Memory access
z7-bit or 10-bit slave addressing
zSequential read/write operations
10.7 USART
zProgrammable Baud Rate Generator
z5- to 9-bit full-duplex synchronous or asynchronous serial communications
z1, 1.5 or 2 stop bits in Asynchronous Mode
z1 or 2 stop bits in Synchronous Mode
zParity generation and error detection
zFraming error detection, overrun error detection
zMSB or LSB first
zOptional break generation and detection
zBy 8 or by 16 over-sampling receiver frequency
zHardware handshaking RTS - CTS
zModem Signals Management DTR-DSR-DCD-RI on USART1 (not present on SAM7S32/16)
zReceiver time-out and transmitter timeguard
zMulti-drop Mode with address generation and detection
zRS485 with driver control signal
zISO7816, T = 0 or T = 1 Protocols for interfacing with smart cards
zNACK handling, error counter with repetition and iteration limit
zIrDA modulation and demodulation
zCommunication at up to 115.2 Kbps
zTest Modes
zRemote Loopback, Local Loopback, Automatic Echo
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10.8 Serial Synchronous Controller
zProvides serial synchronous communication links used in audio and telecom applications
zContains an independent receiver and transmitter and a common clock divider
zOffers a configurable frame sync and data length
zReceiver and transmitter can be programmed to start automatically or on detection of different event on the frame
sync signal
zReceiver and transmitter include a data signal, a clock signal and a frame synchronization signal
10.9 Timer Counter
zThree 16-bit Timer Counter Channels
zTwo output compare or one input capture per channel (except for SAM7S32/16 which have only two
channels connected to the PIO)
zWide range of functions including:
zFrequency measurement
zEvent counting
zInterval measurement
zPulse generation
zDelay timing
zPulse Width Modulation
zUp/down capabilities
zEach channel is user-configurable and contains:
zThree external clock inputs (The SAM7S32/16 have one)
zFive internal clock inputs, as defined in Table 10-5
zTwo multi-purpose input/output signals
zTwo global registers that act on all three TC channels
10.10 PWM Controller
zFour channels, one 16-bit counter per channel
zCommon clock generator, providing thirteen different clocks
zOne Modulo n counter providing eleven clocks
zTwo independent linear dividers working on modulo n counter outputs
zIndependent channel programming
zIndependent enable/disable commands
zIndependent clock selection
zIndependent period and duty cycle, with double buffering
zProgrammable selection of the output waveform polarity
Table 10-5. Timer Counter Clocks Assignment
TC Clock Input Clock
TIMER_CLOCK1 MCK/2
TIMER_CLOCK2 MCK/8
TIMER_CLOCK3 MCK/32
TIMER_CLOCK4 MCK/128
TIMER_CLOCK5 MCK/1024
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zProgrammable center or left aligned output waveform
10.11 USB Device Port (Does not pertain to SAM7S32/16)
zUSB V2.0 full-speed compliant, 12 Mbits per second.
zEmbedded USB V2.0 full-speed transceiver
zEmbedded 328-byte dual-port RAM for endpoints
zFour endpoints
zEndpoint 0: 8 bytes
zEndpoint 1 and 2: 64 bytes ping-pong
zEndpoint 3: 64 bytes
zPing-pong Mode (two memory banks) for isochronous and bulk endpoints
zSuspend/resume logic
10.12 Analog-to-digital Converter
z8-channel ADC
z10-bit 384 Ksamples/sec. or 8-bit 583 Ksamples/sec. Successive Approximation Register ADC
z±2 LSB Integral Non Linearity, ±1 LSB Differential Non Linearity
zIntegrated 8-to-1 multiplexer, offering eight independent 3.3V analog inputs
zExternal voltage reference for better accuracy on low voltage inputs
zIndividual enable and disable of each channel
zMultiple trigger source
zHardware or software trigger
zExternal trigger pin
zTimer Counter 0 to 2 outputs TIOA0 to TIOA2 trigger
zSleep Mode and conversion sequencer
zAutomatic wakeup on trigger and back to sleep mode after conversions of all enabled channels
zFour of eight analog inputs shared with digital signals
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11. ARM7TDMI Processor Overview
11.1 Overview
The ARM7TDMI core executes both the 32-bit ARM® and 16-bit Thumb® instruction sets, allowing the user to trade
off between high performance and high code density.The ARM7TDMI processor implements Von Neuman archi-
tecture, using a three-stage pipeline consisting of Fetch, Decode, and Execute stages.
The main features of the ARM7TDMI processor are:
• ARM7TDMI Based on ARMv4T Architecture
• Two Instruction Sets
–ARM
® High-performance 32-bit Instruction Set
–Thumb
® High Code Density 16-bit Instruction Set
• Three-Stage Pipeline Architecture
– Instruction Fetch (F)
– Instruction Decode (D)
– Execute (E)
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11.2 ARM7TDMI Processor
For further details on ARM7TDMI, refer to the following ARM documents:
ARM Architecture Reference Manual (DDI 0100E)
ARM7TDMI Technical Reference Manual (DDI 0210B)
11.2.1 Instruction Type
Instructions are either 32 bits long (in ARM state) or 16 bits long (in THUMB state).
11.2.2 Data Type
ARM7TDMI supports byte (8-bit), half-word (16-bit) and word (32-bit) data types. Words must be aligned to four-
byte boundaries and half words to two-byte boundaries.
Unaligned data access behavior depends on which instruction is used where.
11.2.3 ARM7TDMI Operating Mode
The ARM7TDMI, based on ARM architecture v4T, supports seven processor modes:
User: The normal ARM program execution state
FIQ: Designed to support high-speed data transfer or channel process
IRQ: Used for general-purpose interrupt handling
Supervisor: Protected mode for the operating system
Abort mode: Implements virtual memory and/or memory protection
System: A privileged user mode for the operating system
Undefined: Supports software emulation of hardware coprocessors
Mode changes may be made under software control, or may be brought about by external interrupts or exception
processing. Most application programs execute in User mode. The non-user modes, or privileged modes, are
entered in order to service interrupts or exceptions, or to access protected resources.
11.2.4 ARM7TDMI Registers
The ARM7TDMI processor has a total of 37registers:
• 31 general-purpose 32-bit registers
• 6 status registers
These registers are not accessible at the same time. The processor state and operating mode determine which
registers are available to the programmer.
At any one time 16 registers are visible to the user. The remainder are synonyms used to speed up exception
processing.
Register 15 is the Program Counter (PC) and can be used in all instructions to reference data relative to the current
instruction.
R14 holds the return address after a subroutine call.
R13 is used (by software convention) as a stack pointer.
Registers R0 to R7 are unbanked registers. This means that each of them refers to the same 32-bit physical regis-
ter in all processor modes. They are general-purpose registers, with no special uses managed by the architecture,
and can be used wherever an instruction allows a general-purpose register to be specified.
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Registers R8 to R14 are banked registers. This means that each of them depends on the current mode of the
processor.
11.2.4.1 Modes and Exception Handling
All exceptions have banked registers for R14 and R13.
After an exception, R14 holds the return address for exception processing. This address is used to return after the
exception is processed, as well as to address the instruction that caused the exception.
R13 is banked across exception modes to provide each exception handler with a private stack pointer.
The fast interrupt mode also banks registers 8 to 12 so that interrupt processing can begin without having to save
these registers.
A seventh processing mode, System Mode, does not have any banked registers. It uses the User Mode registers.
System Mode runs tasks that require a privileged processor mode and allows them to invoke all classes of
exceptions.
11.2.4.2 Status Registers
All other processor states are held in status registers. The current operating processor status is in the Current Pro-
gram Status Register (CPSR). The CPSR holds:
• four ALU flags (Negative, Zero, Carry, and Overflow)
Table 11-1. ARM7TDMI ARM Modes and Registers Layout
User and
System Mode
Supervisor
Mode Abort Mode
Undefined
Mode
Interrupt
Mode
Fast Interrupt
Mode
R0 R0 R0 R0 R0 R0
R1 R1 R1 R1 R1 R1
R2 R2 R2 R2 R2 R2
R3 R3 R3 R3 R3 R3
R4 R4 R4 R4 R4 R4
R5 R5 R5 R5 R5 R5
R6 R6 R6 R6 R6 R6
R7 R7 R7 R7 R7 R7
R8 R8 R8 R8 R8 R8_FIQ
R9 R9 R9 R9 R9 R9_FIQ
R10 R10 R10 R10 R10 R10_FIQ
R11 R11 R11 R11 R11 R11_FIQ
R12 R12 R12 R12 R12 R12_FIQ
R13 R13_SVC R13_ABORT R13_UNDEF R13_IRQ R13_FIQ
R14 R14_SVC R14_ABORT R14_UNDEF R14_IRQ R14_FIQ
PC PC PC PC PC PC
CPSR CPSR CPSR CPSR CPSR CPSR
SPSR_SVC SPSR_ABORT SPSR_UNDEF SPSR_IRQ SPSR_FIQ
Mode-specific banked registers
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• two interrupt disable bits (one for each type of interrupt)
• one bit to indicate ARM or Thumb execution
• five bits to encode the current processor mode
All five exception modes also have a Saved Program Status Register (SPSR) that holds the CPSR of the task
immediately preceding the exception.
11.2.4.3 Exception Types
The ARM7TDMI supports five types of exception and a privileged processing mode for each type. The types of
exceptions are:
• fast interrupt (FIQ)
• normal interrupt (IRQ)
• memory aborts (used to implement memory protection or virtual memory)
• attempted execution of an undefined instruction
• software interrupts (SWIs)
Exceptions are generated by internal and external sources.
More than one exception can occur in the same time.
When an exception occurs, the banked version of R14 and the SPSR for the exception mode are used to save
state.
To return after handling the exception, the SPSR is moved to the CPSR, and R14 is moved to the PC. This can be
done in two ways:
• by using a data-processing instruction with the S-bit set, and the PC as the destination
• by using the Load Multiple with Restore CPSR instruction (LDM)
11.2.5 ARM Instruction Set Overview
The ARM instruction set is divided into:
• Branch instructions
• Data processing instructions
• Status register transfer instructions
• Load and Store instructions
• Coprocessor instructions
• Exception-generating instructions
ARM instructions can be executed conditionally. Every instruction contains a 4-bit condition code field (bit[31:28]).
Table 11-2 gives the ARM instruction mnemonic list.
Table 11-2. ARM Instruction Mnemonic List
Mnemonic Operation Mnemonic Operation
MOV Move CDP Coprocessor Data Processing
ADD Add MVN Move Not
SUB Subtract ADC Add with Carry
RSB Reverse Subtract SBC Subtract with Carry
CMP Compare RSC Reverse Subtract with Carry
TST Test CMN Compare Negated
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11.2.6 Thumb Instruction Set Overview
The Thumb instruction set is a re-encoded subset of the ARM instruction set.
The Thumb instruction set is divided into:
• Branch instructions
• Data processing instructions
• Load and Store instructions
• Load and Store Multiple instructions
• Exception-generating instruction
In Thumb mode, eight general-purpose registers, R0 to R7, are available that are the same physical registers as
R0 to R7 when executing ARM instructions. Some Thumb instructions also access to the Program Counter (ARM
Register 15), the Link Register (ARM Register 14) and the Stack Pointer (ARM Register 13). Further instructions
allow limited access to the ARM registers 8 to 15.
Table 11-3 gives the Thumb instruction mnemonic list.
AND Logical AND TEQ Test Equivalence
EOR Logical Exclusive OR BIC Bit Clear
MUL Multiply ORR Logical (inclusive) OR
SMULL Sign Long Multiply MLA Multiply Accumulate
SMLAL Signed Long Multiply Accumulate UMULL Unsigned Long Multiply
MSR Move to Status Register UMLAL Unsigned Long Multiply Accumulate
B Branch MRS Move From Status Register
BX Branch and Exchange BL Branch and Link
LDR Load Word SWI Software Interrupt
LDRSH Load Signed Halfword STR Store Word
LDRSB Load Signed Byte STRH Store Half Word
LDRH Load Half Word STRB Store Byte
LDRB Load Byte STRBT Store Register Byte with Translation
LDRBT Load Register Byte with Translation STRT Store Register with Translation
LDRT Load Register with Translation STM Store Multiple
LDM Load Multiple SWPB Swap Byte
SWP Swap Word MRC Move From Coprocessor
MCR Move To Coprocessor STC Store From Coprocessor
LDC Load To Coprocessor
Table 11-2. ARM Instruction Mnemonic List
Mnemonic Operation Mnemonic Operation
Table 11-3. Thumb Instruction Mnemonic List
Mnemonic Operation Mnemonic Operation
MOV Move MVN Move Not
ADD Add ADC Add with Carry
SUB Subtract SBC Subtract with Carry
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CMP Compare CMN Compare Negated
TST Test NEG Negate
AND Logical AND BIC Bit Clear
EOR Logical Exclusive OR ORR Logical (inclusive) OR
LSL Logical Shift Left LSR Logical Shift Right
ASR Arithmetic Shift Right ROR Rotate Right
MUL Multiply
B Branch BL Branch and Link
BX Branch and Exchange SWI Software Interrupt
LDR Load Word STR Store Word
LDRH Load Half Word STRH Store Half Word
LDRB Load Byte STRB Store Byte
LDRSH Load Signed Halfword LDRSB Load Signed Byte
LDMIA Load Multiple STMIA Store Multiple
PUSH Push Register to stack POP Pop Register from stack
Table 11-3. Thumb Instruction Mnemonic List
Mnemonic Operation Mnemonic Operation
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12. Debug and Test Features
12.1 Description
The SAM7S Series Microcontrollers feature a number of complementary debug and test capabilities. A common
JTAG/ICE (EmbeddedICE) port is used for standard debugging functions, such as downloading code and single-
stepping through programs. The Debug Unit provides a two-pin UART that can be used to upload an application
into internal SRAM. It manages the interrupt handling of the internal COMMTX and COMMRX signals that trace the
activity of the Debug Communication Channel.
A set of dedicated debug and test input/output pins gives direct access to these capabilities from a PC-based test
environment.
12.2 Block Diagram
Figure 12-1. Debug and Test Block Diagram
ICE
PDC DBGU
PIO
DRXD
DTXD
TST
TMS
TCK
TDI
JTAGSEL
TDO
Boundary
TA P
ICE/JTAG
TA P
ARM7TDMI
Reset
and
Test
POR
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12.3 Application Examples
12.3.1 Debug Environment
Figure 12-2 on page 48 shows a complete debug environment example. The ICE/JTAG interface is used for stan-
dard debugging functions, such as downloading code and single-stepping through the program.
Figure 12-2. Application Debug Environment Example
ICE/JTAG
Interface
Host Debugger
ICE/JTAG
Connector
Terminal
RS232
Connector
SAM7S
SAM7S-based Application Board
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12.3.2 Test Environment
Figure 12-3 on page 49 shows a test environment example. Test vectors are sent and interpreted by the tester. In
this example, the “board in test” is designed using a number of JTAG-compliant devices. These devices can be
connected to form a single scan chain.
Figure 12-3. Application Test Environment Example
JTAG
Interface
ICE/JTAG
Connector
Te st Adaptor
Chip 2Chip n
Chip 1
SAM7S
Te ster
SAM7S-based Application Board In Test
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12.4 Debug and Test Pin Description
Table 12-1. Debug and Test Pin List
Pin Name Function Type Active Level
Reset/Test
NRST Microcontroller Reset Input/Output Low
TST Test Mode Select Input High
ICE and JTAG
TCK Test Clock Input
TDI Test Data In Input
TDO Test Data Out Output
TMS Test Mode Select Input
JTAGSEL JTAG Selection Input
Debug Unit
DRXD Debug Receive Data Input
DTXD Debug Transmit Data Output
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12.5 Functional Description
12.5.1 Test Pin
One dedicated pin, TST, is used to define the device operating mode. The user must make sure that this pin is tied
at low level to ensure normal operating conditions. Other values associated with this pin are reserved for manufac-
turing test.
12.5.2 EmbeddedICE™ (Embedded In-circuit Emulator)
The ARM7TDMI EmbeddedICE is supported via the ICE/JTAG port.The internal state of the ARM7TDMI is exam-
ined through an ICE/JTAG port.
The ARM7TDMI processor contains hardware extensions for advanced debugging features:
• In halt mode, a store-multiple (STM) can be inserted into the instruction pipeline. This exports the contents of
the ARM7TDMI registers. This data can be serially shifted out without affecting the rest of the system.
• In monitor mode, the JTAG interface is used to transfer data between the debugger and a simple monitor
program running on the ARM7TDMI processor.
There are three scan chains inside the ARM7TDMI processor that support testing, debugging, and programming of
the Embedded ICE. The scan chains are controlled by the ICE/JTAG port.
EmbeddedICE mode is selected when JTAGSEL is low. It is not possible to switch directly between ICE and JTAG
operations. A chip reset must be performed after JTAGSEL is changed.
For further details on the EmbeddedICE, see the ARM7TDMI (Rev4) Technical Reference Manual (DDI0210B).
12.5.3 Debug Unit
The Debug Unit provides a two-pin (DXRD and TXRD) USART that can be used for several debug and trace pur-
poses and offers an ideal means for in-situ programming solutions and debug monitor communication. Moreover,
the association with two peripheral data controller channels permits packet handling of these tasks with processor
time reduced to a minimum.
The Debug Unit also manages the interrupt handling of the COMMTX and COMMRX signals that come from the
ICE and that trace the activity of the Debug Communication Channel.The Debug Unit allows blockage of access to
the system through the ICE interface.
A specific register, the Debug Unit Chip ID Register, gives information about the product version and its internal
configuration.
Table 12-2. SAM7S Series Debug Unit Chip ID
Chip Name Chip ID
AT91SAM7S16 Rev A 0x27050240
AT91SAM7S161 Rev A 0x27050241
AT91SAM7S32 Rev A 0x27080340
AT91SAM7S32 Rev B 0x27080341
AT91SAM7S321 Rev A 0x27080342
AT91SAM7S64 Rev A 0x27090540
AT91SAM7S64 Rev B 0x27090543
AT91SAM7S64 Rev C 0x27090544
AT91SAM7S128 Rev A 0x270C0740
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For further details on the Debug Unit, see the Debug Unit section.
12.5.4 IEEE 1149.1 JTAG Boundary Scan
IEEE 1149.1 JTAG Boundary Scan allows pin-level access independent of the device packaging technology.
IEEE 1149.1 JTAG Boundary Scan is enabled when JTAGSEL is high. The SAMPLE, EXTEST and BYPASS func-
tions are implemented. In ICE debug mode, the ARM processor responds with a non-JTAG chip ID that identifies
the processor to the ICE system. This is not IEEE 1149.1 JTAG-compliant.
It is not possible to switch directly between JTAG and ICE operations. A chip reset must be performed after JTAG-
SEL is changed.
A Boundary-scan Descriptor Language (BSDL) file is provided to set up testing.
12.5.4.1 JTAG Boundary-scan Register
The Boundary-scan Register (BSR) contains 96 bits that correspond to active pins and associated control signals.
Each SAM7Sxx input/output pin corresponds to a 3-bit register in the BSR. The OUTPUT bit contains data that
can be forced on the pad. The INPUT bit facilitates the observability of data applied to the pad. The CONTROL bit
selects the direction of the pad.
AT91SAM7S128 Rev B 0x270A0741
AT91SAM7S128 Rev C 0x270A0742
AT91SAM7S128 Rev D 0x270A0743
AT91SAM7S256 Rev A 0x270D0940
AT91SAM7S256 Rev B 0x270B0941
AT91SAM7S256 Rev C 0x270B0942
AT91SAM7S256 Rev D 0x270B0943
AT91SAM7S512 Rev A 0x270B0A40
AT91SAM7S512 Rev B 0x270B0A4F
Table 12-2. SAM7S Series Debug Unit Chip ID (Continued)
Table 12-3. SAM7Sxx JTAG Boundary Scan Register
Bit Number Pin Name Pin Type
Associated BSR
Cells
96
PA17/PGMD5/AD0 IN/OUT
INPUT
95 OUTPUT
94 CONTROL
93
PA18/PGMD6/AD1 IN/OUT
INPUT
92 OUTPUT
91 CONTROL
90
PA21/PGMD9* IN/OUT*
INPUT(1)
89 OUTPUT(1)
88 CONTROL(1)
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87
PA19/PGMD7/AD2 IN/OUT
INPUT
86 OUTPUT
85 CONTROL
84
PA20/PGMD8/AD3 IN/OUT
INPUT
83 OUTPUT
82 CONTROL
81
PA16/PGMD4 IN/OUT
INPUT
80 OUTPUT
79 CONTROL
78
PA15/PGM3 IN/OUT
INPUT
77 OUTPUT
76 CONTROL
75
PA14/PGMD2 IN/OUT
INPUT
74 OUTPUT
73 CONTROL
72
PA13/PGMD1 IN/OUT
INPUT
71 OUTPUT
70 CONTROL
69
PA22/PGMD10* IN/OUT*
INPUT(1)
68 OUTPUT(1)
67 CONTROL(1)
66
PA23/PGMD11* IN/OUT*
INPUT(1)
65 OUTPUT(1)
64 CONTROL(1)
63
PA24/PGMD12* IN/OUT*
INPUT(1)
62 OUTPUT(1)
61 CONTROL(1)
60
PA12/PGMD0 IN/OUT
INPUT
59 OUTPUT
58 CONTROL
57
PA11/PGMM3 IN/OUT
INPUT
56 OUTPUT
55 CONTROL
54
PA10/PGMM2 IN/OUT
INPUT
53 OUTPUT
52 CONTROL
Table 12-3. SAM7Sxx JTAG Boundary Scan Register (Continued)
Bit Number Pin Name Pin Type
Associated BSR
Cells
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51
PA9/PGMM1 IN/OUT
INPUT
50 OUTPUT
49 CONTROL
48
PA8/PGMM0 IN/OUT
INPUT
47 OUTPUT
46 CONTROL
45
PA 7 / P G M N VA L I D I N / O U T
INPUT
44 OUTPUT
43 CONTROL
42
PA6/PGMNOE IN/OUT
INPUT
41 OUTPUT
40 CONTROL
39
PA5/PGMRDY IN/OUT
INPUT
38 OUTPUT
37 CONTROL
36
PA4/PGMNCMD IN/OUT
INPUT
35 OUTPUT
34 CONTROL
33
PA25/PGMD13 IN/OUT
INPUT(1)
32 OUTPUT(1)
31 CONTROL(1)
30
PA26/PGMD14 IN/OUT
INPUT(1)
29 OUTPUT(1)
28 CONTROL(1)
27
PA27/PGMD15 IN/OUT
INPUT(1)
26 OUTPUT(1)
25 CONTROL(1)
24
PA28 IN/OUT
INPUT(1)
23 OUTPUT(1)
22 CONTROL(1)
21
PA 3 I N / O U T
INPUT
20 OUTPUT
19 CONTROL
18
PA 2 I N / O U T
INPUT
17 OUTPUT
16 CONTROL
Table 12-3. SAM7Sxx JTAG Boundary Scan Register (Continued)
Bit Number Pin Name Pin Type
Associated BSR
Cells
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Note: 1. Does not pertain to SAM7S32.
15
PA1/PGMEN1 IN/OUT
INPUT
14 OUTPUT
13 CONTROL
12
PA0/PGMEN0 IN/OUT
INPUT
11 OUTPUT
10 CONTROL
9
PA29 IN/OUT
INPUT(1)
8OUTPUT(1)
7CONTROL(1)
6
PA30 IN/OUT
INPUT(1)
5OUTPUT(1)
4CONTROL(1)
3
PA31 IN/OUT
INPUT(1)
2OUTPUT(1)
1CONTROL(1)
0 ERASE IN INPUT
Table 12-3. SAM7Sxx JTAG Boundary Scan Register (Continued)
Bit Number Pin Name Pin Type
Associated BSR
Cells
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12.5.5 ID Code Register
Access: Read-only
The JTAG D is used in the IEEE 1149.1 JTAG Boundary Scan.
• VERSION[31:28]: Product Version Number
Set to 0x0.
• PART NUMBER[27:12]: Product Part Number
• MANUFACTURER IDENTITY[11:1]
Set to 0x01F.
• Bit[0] Required by IEEE Std. 1149.1.
Set to 0x1.
31 30 29 28 27 26 25 24
VERSION PART NUMBER
23 22 21 20 19 18 17 16
PART NUMBER
15 14 13 12 11 10 9 8
PART NUMBER MANUFACTURER IDENTITY
76543210
MANUFACTURER IDENTITY 1
Chip Name Chip ID
AT91SAM7S16 0x5B22
AT91SAM7S161 0x5B1F
AT91SAM7S32 0x5B07
AT91SAM7S321 0x5B12
AT91SAM7S64 0x5B06
AT91SAM7S128 0x5B09
AT91SAM7S256 0x5B0A
AT91SAM7S512 0x5B1A
Chip Name JTAG ID Code
AT91SAM7S16 05B2_203F
AT91SAM7S161 05B1_F03F
AT91SAM7S32 05B0_703F
AT91SAM7S321 05B1_203F
AT91SAM7S64 05B0_603F
AT91SAM7S128 05B0_A03F
AT91SAM7S256 05B0_903F
AT91SAM7S512 05B1_A03F
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13. Reset Controller (RSTC)
13.1 Overview
The Reset Controller (RSTC), based on power-on reset cells, handles all the resets of the system without any
external components. It reports which reset occurred last.
The Reset Controller also drives independently or simultaneously the external reset and the peripheral and proces-
sor resets.
A brownout detection is also available to prevent the processor from falling into an unpredictable state.
13.2 Block Diagram
Figure 13-1. Reset Controller Block Diagram
NRST
Startup
Counter
proc_nreset
wd_fault
periph_nreset
SLCK
Reset
State
Manager
Reset Controller
brown_out
bod_rst_en
rstc_irq
NRST
Manager
exter_nreset
nrst_out
Main Supply
POR
WDRPROC
user_reset
Brownout
Manager
bod_reset
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13.3 Functional Description
13.3.1 Reset Controller Overview
The Reset Controller is made up of an NRST Manager, a Brownout Manager, a Startup Counter and a Reset State
Manager. It runs at Slow Clock and generates the following reset signals:
• proc_nreset: Processor reset line. It also resets the Watchdog Timer.
• periph_nreset: Affects the whole set of embedded peripherals.
• nrst_out: Drives the NRST pin.
These reset signals are asserted by the Reset Controller, either on external events or on software action. The
Reset State Manager controls the generation of reset signals and provides a signal to the NRST Manager when an
assertion of the NRST pin is required.
The NRST Manager shapes the NRST assertion during a programmable time, thus controlling external device
resets.
The startup counter waits for the complete crystal oscillator startup. The wait delay is given by the crystal oscillator
startup time maximum value that can be found in the section Crystal Oscillator Characteristics in the Electrical
Characteristics section of the product documentation.
13.3.2 NRST Manager
The NRST Manager samples the NRST input pin and drives this pin low when required by the Reset State Man-
ager. Figure 13-2 shows the block diagram of the NRST Manager.
Figure 13-2. NRST Manager
13.3.2.1 NRST Signal or Interrupt
The NRST Manager samples the NRST pin at Slow Clock speed. When the line is detected low, a User Reset is
reported to the Reset State Manager.
However, the NRST Manager can be programmed to not trigger a reset when an assertion of NRST occurs. Writ-
ing the bit URSTEN at 0 in RSTC_MR disables the User Reset trigger.
The level of the pin NRST can be read at any time in the bit NRSTL (NRST level) in RSTC_SR. As soon as the pin
NRST is asserted, the bit URSTS in RSTC_SR is set. This bit clears only when RSTC_SR is read.
The Reset Controller can also be programmed to generate an interrupt instead of generating a reset. To do so, the
bit URSTIEN in RSTC_MR must be written at 1.
External Reset Timer
URSTS
URSTEN
ERSTL
exter_nreset
URSTIEN
RSTC_MR
RSTC_MR
RSTC_MR
RSTC_SR
NRSTL
nrst_out
NRST
rstc_irq
Other
interrupt
sources
user_reset
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13.3.2.2 NRST External Reset Control
The Reset State Manager asserts the signal ext_nreset to assert the NRST pin. When this occurs, the “nrst_out”
signal is driven low by the NRST Manager for a time programmed by the field ERSTL in RSTC_MR. This assertion
duration, named EXTERNAL_RESET_LENGTH, lasts 2(ERSTL+1) Slow Clock cycles. This gives the approximate
duration of an assertion between 60 µs and 2 seconds. Note that ERSTL at 0 defines a two-cycle duration for the
NRST pulse.
This feature allows the Reset Controller to shape the NRST pin level, and thus to guarantee that the NRST line is
driven low for a time compliant with potential external devices connected on the system reset.
13.3.3 Brownout Manager
Brownout detection prevents the processor from falling into an unpredictable state if the power supply drops below
a certain level. When VDDCORE drops below the brownout threshold, the brownout manager requests a brownout
reset by asserting the bod_reset signal.
The programmer can disable the brownout reset by setting low the bod_rst_en input signal, i.e.; by locking the cor-
responding general-purpose NVM bit in the Flash. When the brownout reset is disabled, no reset is performed.
Instead, the brownout detection is reported in the bit BODSTS of RSTC_SR. BODSTS is set and clears only when
RSTC_SR is read.
The bit BODSTS can trigger an interrupt if the bit BODIEN is set in the RSTC_MR.
At factory, the brownout reset is disabled.
Figure 13-3. Brownout Manager
rstc_irq
brown_out
bod_reset
bod_rst_en
BODIEN
RSTC_MR
BODSTS
RSTC_SR
Other
interrupt
sources
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13.3.4 Reset States
The Reset State Manager handles the different reset sources and generates the internal reset signals. It reports
the reset status in the field RSTTYP of the Status Register (RSTC_SR). The update of the field RSTTYP is per-
formed when the processor reset is released.
13.3.4.1 Power-up Reset
When VDDCORE is powered on, the Main Supply POR cell output is filtered with a start-up counter that operates
at Slow Clock. The purpose of this counter is to ensure that the Slow Clock oscillator is stable before starting up the
device.
The startup time, as shown in Figure 13-4, is hardcoded to comply with the Slow Clock Oscillator startup time. After
the startup time, the reset signals are released and the field RSTTYP in RSTC_SR reports a Power-up Reset.
When VDDCORE is detected low by the Main Supply POR Cell, all reset signals are asserted immediately.
Figure 13-4. Power-up Reset
SLCK
periph_nreset
proc_nreset
Main Supply
POR output
NRST
(nrst_out)
EXTERNAL RESET LENGTH
= 2 cycles
Startup Time
MCK
Processor Startup
= 3 cycles
Any
Freq.
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13.3.4.2 User Reset
The User Reset is entered when a low level is detected on the NRST pin and the bit URSTEN in RSTC_MR is at 1.
The NRST input signal is resynchronized with SLCK to insure proper behavior of the system.
The User Reset is entered as soon as a low level is detected on NRST. The Processor Reset and the Peripheral
Reset are asserted.
The User Reset is left when NRST rises, after a two-cycle resynchronization time and a three-cycle processor
startup. The processor clock is re-enabled as soon as NRST is confirmed high.
When the processor reset signal is released, the RSTTYP field of the Status Register (RSTC_SR) is loaded with
the value 0x4, indicating a User Reset.
The NRST Manager guarantees that the NRST line is asserted for EXTERNAL_RESET_LENGTH Slow Clock
cycles, as programmed in the field ERSTL. However, if NRST does not rise after EXTERNAL_RESET_LENGTH
because it is driven low externally, the internal reset lines remain asserted until NRST actually rises.
Figure 13-5. User Reset State
SLCK
periph_nreset
proc_nreset
NRST
NRST
(nrst_out)
>= EXTERNAL RESET LENGTH
MCK
Processor Startup
= 3 cycles
Any
Freq.
Resynch.
2 cycles
RSTTYP Any XXX
Resynch.
2 cycles
0x4 = User Reset
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13.3.4.3 Brownout Reset
When the brown_out/bod_reset signal is asserted, the Reset State Manager immediately enters the Brownout
Reset. In this state, the processor, the peripheral and the external reset lines are asserted.
The Brownout Reset is left Y Slow Clock cycles after the rising edge of brown_out/bod_reset after a two-cycle
resynchronization. An external reset is also triggered.
When the processor reset is released, the field RSTTYP in RSTC_SR is loaded with the value 0x5, thus indicating
that the last reset is a Brownout Reset.
Figure 13-6. Brownout Reset State
SLCK
periph_nreset
proc_nreset
brown_out
or bod_reset
NRST
(nrst_out)
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
MCK
Processor Startup
= 3 cycles
Any
Freq.
RSTTYP Any XXX 0x5 = Brownout Reset
Resynch.
2 cycles
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13.3.4.4 Software Reset
The Reset Controller offers several commands used to assert the different reset signals. These commands are
performed by writing the Control Register (RSTC_CR) with the following bits at 1:
• PROCRST: Writing PROCRST at 1 resets the processor and the watchdog timer.
• PERRST: Writing PERRST at 1 resets all the embedded peripherals, including the memory system, and, in
particular, the Remap Command. The Peripheral Reset is generally used for debug purposes.
Except for Debug purposes, PERRST must always be used in conjunction with PROCRST (PERRST and
PROCRST set both at 1 simultaneously.)
• EXTRST: Writing EXTRST at 1 asserts low the NRST pin during a time defined by the field ERSTL in the Mode
Register (RSTC_MR).
The software reset is entered if at least one of these bits is set by the software. All these commands can be per-
formed independently or simultaneously. The software reset lasts Y Slow Clock cycles.
The internal reset signals are asserted as soon as the register write is performed. This is detected on the Master
Clock (MCK). They are released when the software reset is left, i.e.; synchronously to SLCK.
If EXTRST is set, the nrst_out signal is asserted depending on the programming of the field ERSTL. However, the
resulting falling edge on NRST does not lead to a User Reset.
If and only if the PROCRST bit is set, the Reset Controller reports the software status in the field RSTTYP of the
Status Register (RSTC_SR). Other Software Resets are not reported in RSTTYP.
As soon as a software operation is detected, the bit SRCMP (Software Reset Command in Progress) is set in the
Status Register (RSTC_SR). It is cleared as soon as the software reset is left. No other software reset can be per-
formed while the SRCMP bit is set, and writing any value in RSTC_CR has no effect.
Figure 13-7. Software Reset
13.3.4.5 Watchdog Reset
The Watchdog Reset is entered when a watchdog fault occurs. This state lasts Y Slow Clock cycles.
When in Watchdog Reset, assertion of the reset signals depends on the WDRPROC bit in WDT_MR:
SLCK
periph_nreset
if PERRST=1
proc_nreset
if PROCRST=1
Write RSTC_CR
NRST
(nrst_out)
if EXTRST=1
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
MCK
Processor Startup
= 3 cycles
Any
Freq.
RSTTYP Any XXX 0x3 = Software Reset
Resynch.
1 cycle
SRCMP in RSTC_SR
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• If WDRPROC is 0, the Processor Reset and the Peripheral Reset are asserted. The NRST line is also asserted,
depending on the programming of the field ERSTL. However, the resulting low level on NRST does not result in
a User Reset state.
• If WDRPROC = 1, only the processor reset is asserted.
The Watchdog Timer is reset by the proc_nreset signal. As the watchdog fault always causes a processor reset if
WDRSTEN is set, the Watchdog Timer is always reset after a Watchdog Reset, and the Watchdog is enabled by
default and with a period set to a maximum.
When the WDRSTEN in WDT_MR bit is reset, the watchdog fault has no impact on the reset controller.
Figure 13-8. Watchdog Reset
Only if
WDRPROC = 0
SLCK
periph_nreset
proc_nreset
wd_fault
NRST
(nrst_out)
EXTERNAL RESET LENGTH
8 cycles (ERSTL=2)
MCK
Processor Startup
= 3 cycles
Any
Freq.
RSTTYP Any XXX 0x2 = Watchdog Reset
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13.3.5 Reset State Priorities
The Reset State Manager manages the following priorities between the different reset sources, given in descend-
ing order:
•Power-up Reset
•Brownout Reset
• Watchdog Reset
• Software Reset
• User Reset
Particular cases are listed below:
• When in User Reset:
– A watchdog event is impossible because the Watchdog Timer is being reset by the proc_nreset signal.
– A software reset is impossible, since the processor reset is being activated.
• When in Software Reset:
– A watchdog event has priority over the current state.
– The NRST has no effect.
• When in Watchdog Reset:
– The processor reset is active and so a Software Reset cannot be programmed.
– A User Reset cannot be entered.
13.3.6 Reset Controller Status Register
The Reset Controller status register (RSTC_SR) provides several status fields:
• RSTTYP field: This field gives the type of the last reset, as explained in previous sections.
• SRCMP bit: This field indicates that a Software Reset Command is in progress and that no further software
reset should be performed until the end of the current one. This bit is automatically cleared at the end of the
current software reset.
• NRSTL bit: The NRSTL bit of the Status Register gives the level of the NRST pin sampled on each MCK rising
edge.
• URSTS bit: A high-to-low transition of the NRST pin sets the URSTS bit of the RSTC_SR register. This
transition is also detected on the Master Clock (MCK) rising edge (see Figure 13-9). If the User Reset is
disabled (URSTEN = 0) and if the interruption is enabled by the URSTIEN bit in the RSTC_MR register, the
URSTS bit triggers an interrupt. Reading the RSTC_SR status register resets the URSTS bit and clears the
interrupt.
• BODSTS bit: This bit indicates a brownout detection when the brownout reset is disabled (bod_rst_en = 0). It
triggers an interrupt if the bit BODIEN in the RSTC_MR register enables the interrupt. Reading the RSTC_SR
register resets the BODSTS bit and clears the interrupt.
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Figure 13-9. Reset Controller Status and Interrupt
MCK
NRST
NRSTL
2 cycle
resynchronization
2 cycle
resynchronization
URSTS
read
RSTC_SR
Peripheral Access
rstc_irq
if (URSTEN = 0) and
(URSTIEN = 1)
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13.4 Reset Controller (RSTC) User Interface
Table 13-1. Register Mapping
Offset Register Name Access Reset
0x00 Control Register RSTC_CR Write-only -
0x04 Status Register RSTC_SR Read-only 0x0000_0000
0x08 Mode Register RSTC_MR Read-write 0x0000_0000
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13.4.1 Reset Controller Control Register
Register Name: RSTC_CR
Access Type: Write-only
• PROCRST: Processor Reset
0 = No effect.
1 = If KEY is correct, resets the processor.
• PERRST: Peripheral Reset
0 = No effect.
1 = If KEY is correct, resets the peripherals.
• EXTRST: External Reset
0 = No effect.
1 = If KEY is correct, asserts the NRST pin.
•KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
31 30 29 28 27 26 25 24
KEY
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––EXTRSTPERRST–PROCRST
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13.4.2 Reset Controller Status Register
Register Name: RSTC_SR
Access Type: Read-only
• URSTS: User Reset Status
0 = No high-to-low edge on NRST happened since the last read of RSTC_SR.
1 = At least one high-to-low transition of NRST has been detected since the last read of RSTC_SR.
• BODSTS: Brownout Detection Status
0 = No brownout high-to-low transition happened since the last read of RSTC_SR.
1 = A brownout high-to-low transition has been detected since the last read of RSTC_SR.
• RSTTYP: Reset Type
Reports the cause of the last processor reset. Reading this RSTC_SR does not reset this field.
• NRSTL: NRST Pin Level
Registers the NRST Pin Level at Master Clock (MCK).
• SRCMP: Software Reset Command in Progress
0 = No software command is being performed by the reset controller. The reset controller is ready for a software command.
1 = A software reset command is being performed by the reset controller. The reset controller is busy.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––SRCMPNRSTL
15 14 13 12 11 10 9 8
––––– RSTTYP
76543210
––––––BODSTSURSTS
RSTTYP Reset Type Comments
0 0 0 Power-up Reset VDDCORE rising
0 1 0 Watchdog Reset Watchdog fault occurred
0 1 1 Software Reset Processor reset required by the software
1 0 0 User Reset NRST pin detected low
1 0 1 Brownout Reset BrownOut reset occurred
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13.4.3 Reset Controller Mode Register
Register Name: RSTC_MR
Access Type: Read/Write
• URSTEN: User Reset Enable
0 = The detection of a low level on the pin NRST does not generate a User Reset.
1 = The detection of a low level on the pin NRST triggers a User Reset.
• URSTIEN: User Reset Interrupt Enable
0 = USRTS bit in RSTC_SR at 1 has no effect on rstc_irq.
1 = USRTS bit in RSTC_SR at 1 asserts rstc_irq if URSTEN = 0.
• BODIEN: Brownout Detection Interrupt Enable
0 = BODSTS bit in RSTC_SR at 1 has no effect on rstc_irq.
1 = BODSTS bit in RSTC_SR at 1 asserts rstc_irq.
• ERSTL: External Reset Length
This field defines the external reset length. The external reset is asserted during a time of 2(ERSTL+1) Slow Clock cycles. This
allows assertion duration to be programmed between 60 µs and 2 seconds.
•KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
31 30 29 28 27 26 25 24
KEY
23 22 21 20 19 18 17 16
–––––––BODIEN
15 14 13 12 11 10 9 8
–––– ERSTL
76543210
–––URSTIEN–––URSTEN
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14. Real-time Timer (RTT)
14.1 Overview
The Real-time Timer is built around a 32-bit counter and used to count elapsed seconds. It generates a periodic
interrupt or/and triggers an alarm on a programmed value.
14.2 Block Diagram
Figure 14-1. Real-time Timer
14.3 Functional Description
The Real-time Timer is used to count elapsed seconds. It is built around a 32-bit counter fed by Slow Clock divided
by a programmable 16-bit value. The value can be programmed in the field RTPRES of the Real-time Mode Regis-
ter (RTT_MR).
Programming RTPRES at 0x00008000 corresponds to feeding the real-time counter with a 1 Hz signal (if the Slow
Clock is 32.768 Hz). The 32-bit counter can count up to 232 seconds, corresponding to more than 136 years, then
roll over to 0.
The Real-time Timer can also be used as a free-running timer with a lower time-base. The best accuracy is
achieved by writing RTPRES to 3. Programming RTPRES to 1 or 2 is possible, but may result in losing status
events because the status register is cleared two Slow Clock cycles after read. Thus if the RTT is configured to trig-
ger an interrupt, the interrupt occurs during 2 Slow Clock cycles after reading RTT_SR. To prevent several
executions of the interrupt handler, the interrupt must be disabled in the interrupt handler and re-enabled when the
status register is clear.
The Real-time Timer value (CRTV) can be read at any time in the register RTT_VR (Real-time Value Register). As
this value can be updated asynchronously from the Master Clock, it is advisable to read this register twice at the
same value to improve accuracy of the returned value.
SLCK
RTPRES
RTTINC
ALMS
16-bit
Divider
32-bit
Counter
ALMV
=
CRTV
RTT_MR
RTT_VR
RTT_AR
RTT_SR
RTTINCIEN
RTT_MR
0
10
ALMIEN
rtt_int
RTT_MR
set
set
RTT_SR
read
RTT_SR
reset
reset
RTT_MR
reload
rtt_alarm
RTTRST
RTT_MR
RTTRST
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The current value of the counter is compared with the value written in the alarm register RTT_AR (Real-time Alarm
Register). If the counter value matches the alarm, the bit ALMS in RTT_SR is set. The alarm register is set to its
maximum value, corresponding to 0xFFFF_FFFF, after a reset.
The bit RTTINC in RTT_SR is set each time the Real-time Timer counter is incremented. This bit can be used to
start a periodic interrupt, the period being one second when the RTPRES is programmed with 0x8000 and Slow
Clock equal to 32.768 Hz.
Reading the RTT_SR status register resets the RTTINC and ALMS fields.
Writing the bit RTTRST in RTT_MR immediately reloads and restarts the clock divider with the new programmed
value. This also resets the 32-bit counter.
Note: Because of the asynchronism between the Slow Clock (SCLK) and the System Clock (MCK):
1) The restart of the counter and the reset of the RTT_VR current value register is effective only 2 slow clock cycles
after the write of the RTTRST bit in the RTT_MR register.
2) The status register flags reset is taken into account only 2 slow clock cycles after the read of the RTT_SR (Status
Register).
Figure 14-2. RTT Counting
Prescaler
ALMVALMV-10 ALMV+1
0
RTPRES - 1
RTT
APB cycle
read RTT_SR
ALMS (RTT_SR)
APB Interface
MCK
RTTINC (RTT_SR)
ALMV+2 ALMV+3
...
APB cycle
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14.4 Real-time Timer (RTT) User Interface
Table 14-1. Register Mapping
Offset Register Name Access Reset
0x00 Mode Register RTT_MR Read-write 0x0000_8000
0x04 Alarm Register RTT_AR Read-write 0xFFFF_FFFF
0x08 Value Register RTT_VR Read-only 0x0000_0000
0x0C Status Register RTT_SR Read-only 0x0000_0000
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14.4.1 Real-time Timer Mode Register
Register Name: RTT_MR
Access Type: Read-write
• RTPRES: Real-time Timer Prescaler Value
Defines the number of SLCK periods required to increment the real-time timer. RTPRES is defined as follows:
RTPRES = 0: The Prescaler Period is equal to 216
RTPRES ≠ 0: The Prescaler Period is equal to RTPRES.
• ALMIEN: Alarm Interrupt Enable
0 = The bit ALMS in RTT_SR has no effect on interrupt.
1 = The bit ALMS in RTT_SR asserts interrupt.
• RTTINCIEN: Real-time Timer Increment Interrupt Enable
0 = The bit RTTINC in RTT_SR has no effect on interrupt.
1 = The bit RTTINC in RTT_SR asserts interrupt.
• RTTRST: Real-time Timer Restart
1 = Reloads and restarts the clock divider with the new programmed value. This also resets the 32-bit counter.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–––––RTTRSTRTTINCIENALMIEN
15 14 13 12 11 10 9 8
RTPRES
76543210
RTPRES
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14.4.2 Real-time Timer Alarm Register
Register Name: RTT_AR
Access Type: Read-write
• ALMV: Alarm Value
Defines the alarm value (ALMV+1) compared with the Real-time Timer.
31 30 29 28 27 26 25 24
ALMV
23 22 21 20 19 18 17 16
ALMV
15 14 13 12 11 10 9 8
ALMV
76543210
ALMV
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14.4.3 Real-time Timer Value Register
Register Name: RTT_VR
Access Type: Read-only
• CRTV: Current Real-time Value
Returns the current value of the Real-time Timer.
31 30 29 28 27 26 25 24
CRTV
23 22 21 20 19 18 17 16
CRTV
15 14 13 12 11 10 9 8
CRTV
76543210
CRTV
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14.4.4 Real-time Timer Status Register
Register Name: RTT_SR
Access Type: Read-only
• ALMS: Real-time Alarm Status
0 = The Real-time Alarm has not occurred since the last read of RTT_SR.
1 = The Real-time Alarm occurred since the last read of RTT_SR.
• RTTINC: Real-time Timer Increment
0 = The Real-time Timer has not been incremented since the last read of the RTT_SR.
1 = The Real-time Timer has been incremented since the last read of the RTT_SR.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––RTTINCALMS
80
SAM7S Series [DATASHEET]
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15. Periodic Interval Timer (PIT)
15.1 Overview
The Periodic Interval Timer (PIT) provides the operating system’s scheduler interrupt. It is designed to offer maxi-
mum accuracy and efficient management, even for systems with long response time.
15.2 Block Diagram
Figure 15-1. Periodic Interval Timer
20-bit
Counter
MCK/16
PIV
PIT_MR
CPIV PIT_PIVR PICNT
12-bit
Adder
0
0
read PIT_PIVR
CPIV PICNT
PIT_PIIR
PITS
PIT_SR
set
reset
PITIEN
PIT_MR
pit_irq
1
0
10
MCK
Prescaler
= ?
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15.3 Functional Description
The Periodic Interval Timer aims at providing periodic interrupts for use by operating systems.
The PIT provides a programmable overflow counter and a reset-on-read feature. It is built around two counters: a
20-bit CPIV counter and a 12-bit PICNT counter. Both counters work at Master Clock /16.
The first 20-bit CPIV counter increments from 0 up to a programmable overflow value set in the field PIV of the
Mode Register (PIT_MR). When the counter CPIV reaches this value, it resets to 0 and increments the Periodic
Interval Counter, PICNT. The status bit PITS in the Status Register (PIT_SR) rises and triggers an interrupt, pro-
vided the interrupt is enabled (PITIEN in PIT_MR).
Writing a new PIV value in PIT_MR does not reset/restart the counters.
When CPIV and PICNT values are obtained by reading the Periodic Interval Value Register (PIT_PIVR), the over-
flow counter (PICNT) is reset and the PITS is cleared, thus acknowledging the interrupt. The value of PICNT gives
the number of periodic intervals elapsed since the last read of PIT_PIVR.
When CPIV and PICNT values are obtained by reading the Periodic Interval Image Register (PIT_PIIR), there is no
effect on the counters CPIV and PICNT, nor on the bit PITS. For example, a profiler can read PIT_PIIR without
clearing any pending interrupt, whereas a timer interrupt clears the interrupt by reading PIT_PIVR.
The PIT may be enabled/disabled using the PITEN bit in the PIT_MR register (disabled on reset). The PITEN bit
only becomes effective when the CPIV value is 0. Figure 15-2 illustrates the PIT counting. After the PIT Enable bit
is reset (PITEN= 0), the CPIV goes on counting until the PIV value is reached, and is then reset. PIT restarts count-
ing, only if the PITEN is set again.
The PIT is stopped when the core enters debug state.
Figure 15-2. Enabling/Disabling PIT with PITEN
MCK Prescaler
PIVPIV - 10
PITEN
10
0
15
CPIV 1
restarts MCK Prescaler
01
APB cycle
read PIT_PIVR
0
PICNT
PITS (PIT_SR)
MCK
APB Interface
APB cycle
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15.4 Periodic Interval Timer (PIT) User Interface
Table 15-1. Register Mapping
Offset Register Name Access Reset
0x00 Mode Register PIT_MR Read-write 0x000F_FFFF
0x04 Status Register PIT_SR Read-only 0x0000_0000
0x08 Periodic Interval Value Register PIT_PIVR Read-only 0x0000_0000
0x0C Periodic Interval Image Register PIT_PIIR Read-only 0x0000_0000
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15.4.1 Periodic Interval Timer Mode Register
Register Name: PIT_MR
Access Type: Read-write
• PIV: Periodic Interval Value
Defines the value compared with the primary 20-bit counter of the Periodic Interval Timer (CPIV). The period is equal to
(PIV + 1).
• PITEN: Period Interval Timer Enabled
0 = The Periodic Interval Timer is disabled when the PIV value is reached.
1 = The Periodic Interval Timer is enabled.
• PITIEN: Periodic Interval Timer Interrupt Enable
0 = The bit PITS in PIT_SR has no effect on interrupt.
1 = The bit PITS in PIT_SR asserts interrupt.
31 30 29 28 27 26 25 24
––––––PITIENPITEN
23 22 21 20 19 18 17 16
–––– PIV
15 14 13 12 11 10 9 8
PIV
76543210
PIV
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15.4.2 Periodic Interval Timer Status Register
Register Name: PIT_SR
Access Type: Read-only
• PITS: Periodic Interval Timer Status
0 = The Periodic Interval timer has not reached PIV since the last read of PIT_PIVR.
1 = The Periodic Interval timer has reached PIV since the last read of PIT_PIVR.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––––PITS
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15.4.3 Periodic Interval Timer Value Register
Register Name: PIT_PIVR
Access Type: Read-only
Reading this register clears PITS in PIT_SR.
• CPIV: Current Periodic Interval Value
Returns the current value of the periodic interval timer.
• PICNT: Periodic Interval Counter
Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR.
31 30 29 28 27 26 25 24
PICNT
23 22 21 20 19 18 17 16
PICNT CPIV
15 14 13 12 11 10 9 8
CPIV
76543210
CPIV
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15.4.4 Periodic Interval Timer Image Register
Register Name: PIT_PIIR
Access Type: Read-only
• CPIV: Current Periodic Interval Value
Returns the current value of the periodic interval timer.
• PICNT: Periodic Interval Counter
Returns the number of occurrences of periodic intervals since the last read of PIT_PIVR.
31 30 29 28 27 26 25 24
PICNT
23 22 21 20 19 18 17 16
PICNT CPIV
15 14 13 12 11 10 9 8
CPIV
76543210
CPIV
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16. Watchdog Timer (WDT)
16.1 Overview
The Watchdog Timer can be used to prevent system lock-up if the software becomes trapped in a deadlock. It fea-
tures a 12-bit down counter that allows a watchdog period of up to 16 seconds (slow clock at 32.768 kHz). It can
generate a general reset or a processor reset only. In addition, it can be stopped while the processor is in debug
mode or idle mode.
16.2 Block Diagram
Figure 16-1. Watchdog Timer Block Diagram
=0
10
set
reset
read WDT_SR
or
reset
wdt_fault
(to Reset Controller)
set
reset
WDFIEN
wdt_int
WDT_MR
SLCK
1/128
12-bit Down
Counter
Current
Value
WDD
WDT_MR
<= WDD
WDV
WDRSTT
WDT_MR
WDT_CR
reload
WDUNF
WDERR
reload
write WDT_MR
WDT_MR
WDRSTEN
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16.3 Functional Description
The Watchdog Timer can be used to prevent system lock-up if the software becomes trapped in a deadlock. It is
supplied with VDDCORE. It restarts with initial values on processor reset.
The Watchdog is built around a 12-bit down counter, which is loaded with the value defined in the field WDV of the
Mode Register (WDT_MR). The Watchdog Timer uses the Slow Clock divided by 128 to establish the maximum
Watchdog period to be 16 seconds (with a typical Slow Clock of 32.768 kHz).
After a Processor Reset, the value of WDV is 0xFFF, corresponding to the maximum value of the counter with the
external reset generation enabled (field WDRSTEN at 1 after a Backup Reset). This means that a default Watch-
dog is running at reset, i.e., at power-up. The user must either disable it (by setting the WDDIS bit in WDT_MR) if
he does not expect to use it or must reprogram it to meet the maximum Watchdog period the application requires.
If the watchdog is restarted by writing into WDT_CR register, the WDT_MR register must not be programmed dur-
ing a period of time of 3 slow clock period following the WDT_CR write access. In any case, programming a new
value in WDT_MR automatically initiates a restart instruction.
The Watchdog Mode Register (WDT_MR) can be written only once. Only a processor reset resets it. Writing the
WDT_MR register reloads the timer with the newly programmed mode parameters.
In normal operation, the user reloads the Watchdog at regular intervals before the timer underflow occurs, by writ-
ing the Control Register (WDT_CR) with the bit WDRSTT to 1. The Watchdog counter is then immediately
reloaded from WDT_MR and restarted, and the Slow Clock 128 divider is reset and restarted. The WDT_CR regis-
ter is write-protected. As a result, writing WDT_CR without the correct hard-coded key has no effect. If an
underflow does occur, the “wdt_fault” signal to the Reset Controller is asserted if the bit WDRSTEN is set in the
Mode Register (WDT_MR). Moreover, the bit WDUNF is set in the Watchdog Status Register (WDT_SR).
To prevent a software deadlock that continuously triggers the Watchdog, the reload of the Watchdog must occur
while the Watchdog counter is within a window between 0 and WDD, WDD is defined in the WatchDog Mode Reg-
ister WDT_MR.
Any attempt to restart the Watchdog while the Watchdog counter is between WDV and WDD results in a Watchdog
error, even if the Watchdog is disabled. The bit WDERR is updated in the WDT_SR and the “wdt_fault” signal to
the Reset Controller is asserted.
Note that this feature can be disabled by programming a WDD value greater than or equal to the WDV value. In
such a configuration, restarting the Watchdog Timer is permitted in the whole range [0; WDV] and does not gener-
ate an error. This is the default configuration on reset (the WDD and WDV values are equal).
The status bits WDUNF (Watchdog Underflow) and WDERR (Watchdog Error) trigger an interrupt, provided the bit
WDFIEN is set in the mode register. The signal “wdt_fault” to the reset controller causes a Watchdog reset if the
WDRSTEN bit is set as already explained in the reset controller programmer Datasheet. In that case, the proces-
sor and the Watchdog Timer are reset, and the WDERR and WDUNF flags are reset.
If a reset is generated or if WDT_SR is read, the status bits are reset, the interrupt is cleared, and the “wdt_fault”
signal to the reset controller is deasserted.
Writing the WDT_MR reloads and restarts the down counter.
While the processor is in debug state or in idle mode, the counter may be stopped depending on the value pro-
grammed for the bits WDIDLEHLT and WDDBGHLT in the WDT_MR.
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Figure 16-2. Watchdog Behavior
0
WDV
WDD
WDT_CR = WDRSTT
Watchdog
Fault
Normal behavior
Watchdog Error Watchdog Underflow
FFF
if WDRSTEN is 1
if WDRSTEN is 0
Forbidden
Window
Permitted
Window
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16.4 Watchdog Timer (WDT) User Interface
16.4.1 Watchdog Timer Control Register
Register Name: WDT_CR
Access Type: Write-only
• WDRSTT: Watchdog Restart
0: No effect.
1: Restarts the Watchdog.
•KEY: Password
Should be written at value 0xA5. Writing any other value in this field aborts the write operation.
Table 16-1. Register Mapping
Offset Register Name Access Reset
0x00 Control Register WDT_CR Write-only -
0x04 Mode Register WDT_MR Read-write Once 0x3FFF_2FFF
0x08 Status Register WDT_SR Read-only 0x0000_0000
31 30 29 28 27 26 25 24
KEY
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––––WDRSTT
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16.4.2 Watchdog Timer Mode Register
Register Name: WDT_MR
Access Type: Read-write Once
• WDV: Watchdog Counter Value
Defines the value loaded in the 12-bit Watchdog Counter.
• WDFIEN: Watchdog Fault Interrupt Enable
0: A Watchdog fault (underflow or error) has no effect on interrupt.
1: A Watchdog fault (underflow or error) asserts interrupt.
• WDRSTEN: Watchdog Reset Enable
0: A Watchdog fault (underflow or error) has no effect on the resets.
1: A Watchdog fault (underflow or error) triggers a Watchdog reset.
• WDRPROC: Watchdog Reset Processor
0: If WDRSTEN is 1, a Watchdog fault (underflow or error) activates all resets.
1: If WDRSTEN is 1, a Watchdog fault (underflow or error) activates the processor reset.
• WDD: Watchdog Delta Value
Defines the permitted range for reloading the Watchdog Timer.
If the Watchdog Timer value is less than or equal to WDD, writing WDT_CR with WDRSTT = 1 restarts the timer.
If the Watchdog Timer value is greater than WDD, writing WDT_CR with WDRSTT = 1 causes a Watchdog error.
• WDDBGHLT: Watchdog Debug Halt
0: The Watchdog runs when the processor is in debug state.
1: The Watchdog stops when the processor is in debug state.
• WDIDLEHLT: Watchdog Idle Halt
0: The Watchdog runs when the system is in idle mode.
1: The Watchdog stops when the system is in idle state.
• WDDIS: Watchdog Disable
0: Enables the Watchdog Timer.
1: Disables the Watchdog Timer.
31 30 29 28 27 26 25 24
– – WDIDLEHLT WDDBGHLT WDD
23 22 21 20 19 18 17 16
WDD
15 14 13 12 11 10 9 8
WDDIS WDRPROC WDRSTEN WDFIEN WDV
76543210
WDV
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16.4.3 Watchdog Timer Status Register
Register Name: WDT_SR
Access Type: Read-only
• WDUNF: Watchdog Underflow
0: No Watchdog underflow occurred since the last read of WDT_SR.
1: At least one Watchdog underflow occurred since the last read of WDT_SR.
• WDERR: Watchdog Error
0: No Watchdog error occurred since the last read of WDT_SR.
1: At least one Watchdog error occurred since the last read of WDT_SR.
Note:The WDD and WDV values must not be modified within a period of time of 3 slow clock periods following a restart of
the watchdog performed by means of a write access in the WDT_CR register, else the watchdog may trigger an end of
period earlier than expected.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––WDERRWDUNF
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17. Voltage Regulator Mode Controller (VREG)
17.1 Overview
The Voltage Regulator Mode Controller contains one Read/Write register, the Voltage Regulator Mode Register.
Its offset is 0x60 with respect to the System Controller offset.
This register controls the Voltage Regulator Mode. Setting PSTDBY (bit 0) puts the Voltage Regulator in Standby
Mode or Low-power Mode. On reset, the PSTDBY is reset, so as to wake up the Voltage Regulator in Normal
Mode.
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17.2 Voltage Regulator Power Controller (VREG) User Interface
17.2.1 Voltage Regulator Mode Register
Register Name: VREG_MR
Access Type: Read-write
• PSTDBY: Periodic Interval Value
0 = Voltage regulator in normal mode.
1 = Voltage regulator in standby mode (low-power mode).
Table 17-1. Register Mapping
Offset Register Name Access Reset
0x60 Voltage Regulator Mode Register VREG_MR Read-write 0x0
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––––PSTDBY
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18. Memory Controller (MC)
18.1 Overview
The Memory Controller (MC) manages the ASB bus and controls accesses requested by the masters, typically the
ARM7TDMI processor and the Peripheral DMA Controller. It features a simple bus arbiter, an address decoder, an
abort status, a misalignment detector and an Embedded Flash Controller.
18.2 Block Diagram
Figure 18-1. Memory Controller Block Diagram
18.3 Functional Description
The Memory Controller handles the internal ASB bus and arbitrates the accesses of both masters.
ARM7TDMI
Processor
Bus
Arbiter
Peripheral
DMA
Controller
Memory Controller
Abort
ASB
Abort
Status
Address
Decoder
User
Interface
Peripheral 0
Peripheral 1
Internal
RAM
APB
APB
Bridge
Misalignment
Detector
From Master
to Slave
Peripheral N
Embedded
Flash
Controller
Internal
Flash
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It is made up of:
• A bus arbiter
• An address decoder
• An abort status
• A misalignment detector
• An Embedded Flash Controller
The MC handles only little-endian mode accesses. The masters work in little-endian mode only.
18.3.1 Bus Arbiter
The Memory Controller has a simple, hard-wired priority bus arbiter that gives the control of the bus to one of the
two masters. The Peripheral DMA Controller has the highest priority; the ARM processor has the lowest one.
18.3.2 Address Decoder
The Memory Controller features an Address Decoder that first decodes the four highest bits of the 32-bit address
bus and defines three separate areas:
• One 256-Mbyte address space for the internal memories
• One 256-Mbyte address space reserved for the embedded peripherals
• An undefined address space of 3584M bytes representing fourteen 256-Mbyte areas that return an Abort if
accessed
Figure 18-2 shows the assignment of the 256-Mbyte memory areas.
Figure 18-2. Memory Areas
18.3.2.1 Internal Memory Mapping
Within the Internal Memory address space, the Address Decoder of the Memory Controller decodes eight more
address bits to allocate 1-Mbyte address spaces for the embedded memories.
The allocated memories are accessed all along the 1-Mbyte address space and so are repeated n times within this
address space, n equaling 1M bytes divided by the size of the memory.
When the address of the access is undefined within the internal memory area, the Address Decoder returns an
Abort to the master.
0x0000 0000
0x0FFF FFFF
0x1000 0000
0xEFFF FFFF
0xF000 0000
0xFFFF FFFF
256M Bytes
256M Bytes
14 x 256MBytes
3,584 Mbytes
Internal Memories
Undefined
(Abort)
Peripherals
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If an access is done in the address area 0x0030 000 to 0x003F FFFF, no abort is generated.
Figure 18-3. Internal Memory Mapping
18.3.2.2 Internal Memory Area 0
The first 32 bytes of Internal Memory Area 0 contain the ARM processor exception vectors, in particular, the Reset
Vector at address 0x0.
Before execution of the remap command, the on-chip Flash is mapped into Internal Memory Area 0, so that the
ARM7TDMI reaches an executable instruction contained in Flash. After the remap command, the internal SRAM at
address 0x0020 0000 is mapped into Internal Memory Area 0. The memory mapped into Internal Memory Area 0 is
accessible in both its original location and at address 0x0.
18.3.3 Remap Command
After execution, the Remap Command causes the Internal SRAM to be accessed through the Internal Memory
Area 0.
As the ARM vectors (Reset, Abort, Data Abort, Prefetch Abort, Undefined Instruction, Interrupt, and Fast Interrupt)
are mapped from address 0x0 to address 0x20, the Remap Command allows the user to redefine dynamically
these vectors under software control.
The Remap Command is accessible through the Memory Controller User Interface by writing the MC_RCR
(Remap Control Register) RCB field to one.
The Remap Command can be cancelled by writing the MC_RCR RCB field to one, which acts as a toggling com-
mand. This allows easy debug of the user-defined boot sequence by offering a simple way to put the chip in the
same configuration as after a reset.
18.3.4 Abort Status
There are three reasons for an abort to occur:
• access to an undefined address
• an access to a misaligned address.
When an abort occurs, a signal is sent back to all the masters, regardless of which one has generated the access.
However, only the ARM7TDMI can take an abort signal into account, and only under the condition that it was gen-
erating an access. The Peripheral DMA Controller does not handle the abort input signal. Note that the connection
is not represented in Figure 18-1.
256M Bytes
Internal Memory Area 0
Undefined Areas
(Abort)
0x0000 0000
0x000F FFFF
0x0010 0000
0x001F FFFF
0x0020 0000
0x002F FFFF
0x0FFF FFFF
1M Bytes
1M Bytes
1M Bytes
253M bytes
Internal Memory Area 1
Internal Flash
Internal Memory Area 2
Internal SRAM
0x0030 0000
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To facilitate debug or for fault analysis by an operating system, the Memory Controller integrates an Abort Status
register set.
The full 32-bit wide abort address is saved in MC_AASR. Parameters of the access are saved in MC_ASR and
include:
• the size of the request (field ABTSZ)
• the type of the access, whether it is a data read or write, or a code fetch (field ABTTYP)
• whether the access is due to accessing an undefined address (bit UNDADD) or a misaligned address (bit
MISADD)
• the source of the access leading to the last abort (bits MST0 and MST1)
• whether or not an abort occurred for each master since the last read of the register (bit SVMST0 and SVMST1)
unless this information is loaded in MST bits
In the case of a Data Abort from the processor, the address of the data access is stored. This is useful, as search-
ing for which address generated the abort would require disassembling the instructions and full knowledge of the
processor context.
In the case of a Prefetch Abort, the address may have changed, as the prefetch abort is pipelined in the ARM pro-
cessor. The ARM processor takes the prefetch abort into account only if the read instruction is executed and it is
probable that several aborts have occurred during this time. Thus, in this case, it is preferable to use the content of
the Abort Link register of the ARM processor.
18.3.5 Embedded Flash Controller
The Embedded Flash Controller is added to the Memory Controller and ensures the interface of the Flash block
with the 32-bit internal bus. It increases performance in Thumb Mode for Code Fetch with its system of 32-bit buf-
fers. It also manages with the programming, erasing, locking and unlocking sequences thanks to a full set of
commands.
18.3.6 Misalignment Detector
The Memory Controller features a Misalignment Detector that checks the consistency of the accesses.
For each access, regardless of the master, the size of the access and the bits 0 and 1 of the address bus are
checked. If the type of access is a word (32-bit) and the bits 0 and 1 are not 0, or if the type of the access is a half-
word (16-bit) and the bit 0 is not 0, an abort is returned to the master and the access is cancelled. Note that the
accesses of the ARM processor when it is fetching instructions are not checked.
The misalignments are generally due to software bugs leading to wrong pointer handling. These bugs are particu-
larly difficult to detect in the debug phase.
As the requested address is saved in the Abort Status Register and the address of the instruction generating the
misalignment is saved in the Abort Link Register of the processor, detection and fix of this kind of software bug is
simplified.
18.4 Memory Controller (MC) User Interface
Base Address: 0xFFFFFF00
Table 18-1. Register Mapping
Offset Register Name Access Reset
0x00 MC Remap Control Register MC_RCR Write-only
0x04 MC Abort Status Register MC_ASR Read-only 0x0
0x08 MC Abort Address Status Register MC_AASR Read-only 0x0
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Note: 1. SAM7S512 only.
0x0C-0x5C Reserved – – –
0x60 EFC0 Configuration Registers See Section 19. “Embedded Flash Controller (EFC)” on page 105.
0x70 EFC1 Configuration Registers (1)
Table 18-1. Register Mapping
Offset Register Name Access Reset
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18.4.1 MC Remap Control Register
Register Name:MC_RCR
Access Type: Write-only
Offset:0x00
• RCB: Remap Command Bit
0: No effect.
1: This Command Bit acts on a toggle basis: writing a 1 alternatively cancels and restores the remapping of the page zero
memory devices.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––––RCB
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18.4.2 MC Abort Status Register
Register Name:MC_ASR
Access Type: Read-only
Reset Value:0x0
Offset:0x04
• UNDADD: Undefined Address Abort Status
0: The last abort was not due to the access of an undefined address in the address space.
1: The last abort was due to the access of an undefined address in the address space.
• MISADD: Misaligned Address Abort Status
0: The last aborted access was not due to an address misalignment.
1: The last aborted access was due to an address misalignment.
• ABTSZ: Abort Size Status.
• ABTTYP: Abort Type Status.
• MST0: PDC Abort Source
0: The last aborted access was not due to the PDC.
1: The last aborted access was due to the PDC.
• MST1: ARM7TDMI Abort Source
31 30 29 28 27 26 25 24
––––––SVMST1SVMST0
23 22 21 20 19 18 17 16
––––––MST1MST0
15 14 13 12 11 10 9 8
– – – – ABTTYP ABTSZ
76543210
––––––MISADDUNDADD
ABTSZ Abort Size
00 Byte
0 1 Half-word
10 Word
11 Reserved
ABTTYP Abort Type
0 0 Data Read
0 1 Data Write
1 0 Code Fetch
11 Reserved
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0: The last aborted access was not due to the ARM7TDMI.
1: The last aborted access was due to the ARM7TDMI.
• SVMST0: Saved PDC Abort Source
0: No abort due to the PDC occurred.
1: At least one abort due to the PDC occurred.
• SVMST1: Saved ARM7TDMI Abort Source
0: No abort due to the ARM7TDMI occurred.
1: At least one abort due to the ARM7TDMI occurred.
18.4.3 MC Abort Address Status Register
Register Name: MC_AASR
Access Type: Read-only
Reset Value:0x0
Offset:0x08
• ABTADD: Abort Address
This field contains the address of the last aborted access.
31 30 29 28 27 26 25 24
ABTADD
23 22 21 20 19 18 17 16
ABTADD
15 14 13 12 11 10 9 8
ABTADD
76543210
ABTADD
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19. Embedded Flash Controller (EFC)
19.1 Overview
The Embedded Flash Controller (EFC ) is a part of the Memory Controller and ensures the interface of the Flash
block with the 32-bit internal bus. It increases performance in Thumb Mode for Code Fetch with its system of 32-bit
buffers. It also manages the programming, erasing, locking and unlocking sequences using a full set of commands.
The SAM7S512 is equipped with two EFCs, EFC0 and EFC1. EFC1 does not feature the Security bit and GPNVM
bit. The Security and GPNVM bits embedded only on EFC0 apply to the two blocks in the SAM7S512.
19.2 Functional Description
19.2.1 Embedded Flash Organization
The Embedded Flash interfaces directly to the 32-bit internal bus. It is composed of several interfaces:
• One memory plane organized in several pages of the same size
• Two 32-bit read buffers used for code read optimization (see “Read Operations” on page 107).
• One write buffer that manages page programming. The write buffer size is equal to the page size. This buffer is
write-only and accessible all along the 1 MByte address space, so that each word can be written to its final
address (see “Write Operations” on page 109).
• Several lock bits used to protect write and erase operations on lock regions. A lock region is composed of
several consecutive pages, and each lock region has its associated lock bit.
• Several general-purpose NVM bits. Each bit controls a specific feature in the device. Refer to the product
definition section to get the GPNVM assignment.
The Embedded Flash size, the page size and the lock region organization are described in the product definition
section.
Table 19-1. Product Specific Lock and General-purpose NVM Bits
SAM7S512 SAM7S256 SAM7S128 SAM7S64 SAM7S321 SAM7S32 SAM7S161 SAM7S16 Denomination
2 2 2 2 2 2 2 2 Number of GPNVM bits
32 16 8 16 8 8 8 8 Number of Lock Bits
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Figure 19-1. Embedded Flash Memory Mapping
Lock Region 0
Lock Region
(n-1)
Page 0
Page (m-1)
Start Address
32-bit wide
Flash Memory
Page ( (n-1)*m )
Page (n*m-1)
Lock Bit 0
Lock Region 1 Lock Bit 1
Lock Bit n-1
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19.2.2 Read Operations
An optimized controller manages embedded Flash reads. A system of 2 x 32-bit buffers is added in order to start
access at following address during the second read, thus increasing performance when the processor is running in
Thumb mode (16-bit instruction set). See Figure 19-2, Figure 19-3 and Figure 19-4.
This optimization concerns only Code Fetch and not Data.
The read operations can be performed with or without wait state. Up to 3 wait states can be programmed in the
field FWS (Flash Wait State) in the Flash Mode Register MC_FMR (see “MC Flash Mode Register” on page 115).
Defining FWS to be 0 enables the single-cycle access of the embedded Flash.
The Flash memory is accessible through 8-, 16- and 32-bit reads.
As the Flash block size is smaller than the address space reserved for the internal memory area, the embedded
Flash wraps around the address space and appears to be repeated within it.
Figure 19-2. Code Read Optimization in Thumb Mode for FWS = 0
Note: When FWS is equal to 0, all accesses are performed in a single-cycle access.
Figure 19-3. Code Read Optimization in Thumb Mode for FWS = 1
Note: When FWS is equal to 1, in case of sequential reads, all the accesses are performed in a single-cycle access (except for the
first one).
Flash Access
Buffer (32 bits)
Master Clock
ARM Request (16-bit)
Code Fetch
Data To ARM
Bytes 0-3 Bytes 4-7
Bytes 0-3
Bytes 0-1 Bytes 2-3 Bytes 4-5 Bytes 6-7 Bytes 8-9 Bytes 10-11 Bytes 12-13
@Byte 0 @Byte 2 @Byte 4 @Byte 6 @Byte 8 @Byte 10 @Byte 12 @Byte 14 @Byte 16
Bytes 14-15
Bytes 4-7
Bytes 8-11
Bytes 8-11
Bytes 12-15 Bytes 16-19
Bytes 12-15
Flash Access
Buffer (32 bits)
Master Clock
ARM Request (16-bit)
Code Fetch
Data To ARM
Bytes 0-3 Bytes 4-7
Bytes 0-3
Bytes 2-3 Bytes 4-5 Bytes 6-7 Bytes 8-9 Bytes 10-11
@Byte 0 @Byte 4 @Byte 6 @Byte 8 @Byte 10 @Byte 12 @Byte 14
Bytes 4-7
Bytes 8-11
Bytes 8-11
Bytes 12-15
1 Wait State Cycle
Bytes 0-1
1 Wait State Cycle 1 Wait State Cycle 1 Wait State Cycle
@Byte 2
Bytes 12-13
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Figure 19-4. Code Read Optimization in Thumb Mode for FWS = 3
Note: When FWS is equal to 2 or 3, in case of sequential reads, the first access takes FWS cycles, the second access one cycle, the
third access FWS cycles, the fourth access one cycle, etc.
Flash Access
Master Clock
Data To ARM 0-1
@Byte 0 @2
Bytes 0-3 Bytes 4-7 Bytes 8-11 Bytes 12-15
Bytes 0-3
2-3 6-7
@4
8-9 10-11
4-5
@8 @12
Bytes 4-7
3 Wait State Cycles
Buffer (32 bits)
ARM Request (16-bit)
Code Fetch
Bytes 8-11
3 Wait State Cycles 3 Wait State Cycles 3 Wait State Cycles
@6 @10
12-13
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19.2.3 Write Operations
The internal memory area reserved for the embedded Flash can also be written through a write-only latch buffer.
Write operations take into account only the 8 lowest address bits and thus wrap around within the internal memory
area address space and appear to be repeated 1024 times within it.
Write operations can be prevented by programming the Memory Protection Unit of the product.
Writing 8-bit and 16-bit data is not allowed and may lead to unpredictable data corruption.
Write operations are performed in the number of wait states equal to the number of wait states for read operations
+ 1, except for FWS = 3 (see “MC Flash Mode Register” on page 115).
19.2.4 Flash Commands
The EFC offers a command set to manage programming the memory flash, locking and unlocking lock sectors,
consecutive programming and locking, and full Flash erasing.
To run one of these commands, the field FCMD of the MC_FCR register has to be written with the command num-
ber. As soon as the MC_FCR register is written, the FRDY flag is automatically cleared. Once the current
command is achieved, then the FRDY flag is automatically set. If an interrupt has been enabled by setting the bit
FRDY in MC_FMR, the interrupt line of the Memory Controller is activated.
All the commands are protected by the same keyword, which has to be written in the eight highest bits of the
MC_FCR register.
Writing MC_FCR with data that does not contain the correct key and/or with an invalid command has no effect on
the memory plane; however, the PROGE flag is set in the MC_FSR register. This flag is automatically cleared by a
read access to the MC_FSR register.
When the current command writes or erases a page in a locked region, the command has no effect on the whole
memory plane; however, the LOCKE flag is set in the MC_FSR register. This flag is automatically cleared by a read
access to the MC_FSR register.
Table 19-2. Set of Commands
Command Value Mnemonic
Write page 0x01 WP
Set Lock Bit 0x02 SLB
Write Page and Lock 0x03 WPL
Clear Lock Bit 0x04 CLB
Erase all 0x08 EA
Set General-purpose NVM Bit 0x0B SGPB
Clear General-purpose NVM Bit 0x0D CGPB
Set Security Bit 0x0F SSB
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Figure 19-5. Command State Chart
In order to guarantee valid operations on the Flash memory, the field Flash Microsecond Cycle Number (FMCN) in
the Flash Mode Register MC_FMR must be correctly programmed (see “MC Flash Mode Register” on page 115).
19.2.4.1 Flash Programming
Several commands can be used to program the Flash.
The Flash technology requires that an erase must be done before programming. The entire memory plane can be
erased at the same time, or a page can be automatically erased by clearing the NEBP bit in the MC_FMR register
before writing the command in the MC_FCR register.
By setting the NEBP bit in the MC_FMR register, a page can be programmed in several steps if it has been erased
before (see Figure 19-6).
Check if FRDY flag set
No
Yes
Read Status: MC_FSR
Write FCMD and PAGENB in MC_FCR
Check if LOCKE flag set
Check if FRDY flag set
No
Read Status: MC_FSR
Yes
Yes Locking region violation
No
Check if PROGE flag set Yes
No
Bad keyword violation and/or Invalid command
Command Successful
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Figure 19-6. Example of Partial Page Programming
The Partial Programming mode works only with 32-bit (or higher) boundaries. It cannot be used with boundaries
lower than 32 bits (8 or 16-bit for example).
After programming, the page (the whole lock region) can be locked to prevent miscellaneous write or erase
sequences. The lock bit can be automatically set after page programming using WPL.
Data to be written are stored in an internal latch buffer. The size of the latch buffer corresponds to the page size.
The latch buffer wraps around within the internal memory area address space and appears to be repeated by the
number of pages in it.
Note: Writing of 8-bit and 16-bit data is not allowed and may lead to unpredictable data corruption.
Data are written to the latch buffer before the programming command is written to the Flash Command Register
MC_FCR. The sequence is as follows:
• Write the full page, at any page address, within the internal memory area address space using only 32-bit
access.
• Programming starts as soon as the page number and the programming command are written to the Flash
Command Register. The FRDY bit in the Flash Programming Status Register (MC_FSR) is automatically
cleared.
• When programming is completed, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If
an interrupt was enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
Two errors can be detected in the MC_FSR register after a programming sequence:
• Programming Error: A bad keyword and/or an invalid command have been written in the MC_FCR register.
• Lock Error: The page to be programmed belongs to a locked region. A command must be previously run to
unlock the corresponding region.
19.2.4.2 Erase All Command
The entire memory can be erased if the Erase All Command (EA) in the Flash Command Register MC_FCR is
written.
Erase All operation is allowed only if there are no lock bits set. Thus, if at least one lock region is locked, the bit
LOCKE in MC_FSR rises and the command is cancelled. If the bit LOCKE has been written at 1 in MC_FMR, the
interrupt line rises.
Erase All Flash Programming of the second part of Page 7 Programming of the third part of Page 7
32 bits wide 32 bits wide 32 bits wide
16 words
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
...
CA FE CA FE
CA FE CA FE
CA FE CA FE
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
CA FE CA FE
CA FE CA FE
CA FE CA FE
DE CA DE CA
DE CA DE CA
DE CA DE CA
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
FF FF FF FF
Step 1. Step 2. Step 3.
...
...
...
...
...
...
...
...
...
...
...
(NEBP = 1) (NEBP = 1)
16 words
16 words
16 words
Page 7 erased
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When programming is complete, the bit FRDY bit in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
Two errors can be detected in the MC_FSR register after a programming sequence:
• Programming Error: A bad keyword and/or an invalid command have been written in the MC_FCR register.
• Lock Error: At least one lock region to be erased is protected. The erase command has been refused and no
page has been erased. A Clear Lock Bit command must be executed previously to unlock the corresponding
lock regions.
19.2.4.3 Lock Bit Protection
Lock bits are associated with several pages in the embedded Flash memory plane. This defines lock regions in the
embedded Flash memory plane. They prevent writing/erasing protected pages.
After production, the device may have some embedded Flash lock regions locked. These locked regions are
reserved for a default application. Refer to the product definition section for the default embedded Flash mapping.
Locked sectors can be unlocked to be erased and then programmed with another application or other data.
The lock sequence is:
• The Flash Command register must be written with the following value:
(0x5A << 24) | (lockPageNumber << 8 & PAGEN) | SLB
lockPageNumber is a page of the corresponding lock region.
• When locking completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
A programming error, where a bad keyword and/or an invalid command have been written in the MC_FCR register,
may be detected in the MC_FSR register after a programming sequence.
It is possible to clear lock bits that were set previously. Then the locked region can be erased or programmed. The
unlock sequence is:
• The Flash Command register must be written with the following value:
(0x5A << 24) | (lockPageNumber << 8 & PAGEN) | CLB
lockPageNumber is a page of the corresponding lock region.
• When the unlock completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
A programming error, where a bad keyword and/or an invalid command have been written in the MC_FCR register,
may be detected in the MC_FSR register after a programming sequence.
The Unlock command programs the lock bit to 1; the corresponding bit LOCKSx in MC_FSR reads 0. The Lock
command programs the lock bit to 0; the corresponding bit LOCKSx in MC_FSR reads 1.
Note: Access to the Flash in Read Mode is permitted when a Lock or Unlock command is performed.
19.2.4.4 General-purpose NVM Bits
General-purpose NVM bits do not interfere with the embedded Flash memory plane. (Does not apply to EFC1 on
the SAM7S512.) These general-purpose bits are dedicated to protect other parts of the product. They can be set
(activated) or cleared individually. Refer to the product definition section for the general-purpose NVM bit action.
The activation sequence is:
• Start the Set General Purpose Bit command (SGPB) by writing the Flash Command Register with the SEL
command and the number of the general-purpose bit to be set in the PAGEN field.
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• When the bit is set, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an interrupt has
been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is activated.
Two errors can be detected in the MC_FSR register after a programming sequence:
• Programming Error: A bad keyword and/or an invalid command have been written in the MC_FCR register
• If the general-purpose bit number is greater than the total number of general-purpose bits, then the command
has no effect.
It is possible to deactivate a general-purpose NVM bit set previously. The clear sequence is:
• Start the Clear General-purpose Bit command (CGPB) by writing the Flash Command Register with CGPB and
the number of the general-purpose bit to be cleared in the PAGEN field.
• When the clear completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
Two errors can be detected in the MC_FSR register after a programming sequence:
• Programming Error: a bad keyword and/or an invalid command have been written in the MC_FCR register
• If the number of the general-purpose bit set in the PAGEN field is greater than the total number of general-
purpose bits, then the command has no effect.
The Clear General-purpose Bit command programs the general-purpose NVM bit to 0; the corresponding bit
GPNVM0 to GPNVMx in MC_FSR reads 0. The Set General-purpose Bit command programs the general-purpose
NVM bit to 1; the corresponding bit GPNVMx in MC_FSR reads 1.
Note: Access to the Flash in read mode is permitted when a Set, Clear or Get General-purpose NVM Bit command is
performed.
19.2.4.5 Security Bit
The goal of the security bit is to prevent external access to the internal bus system. (Does not apply to EFC1 on
theSAM7S512.) JTAG, Fast Flash Programming and Flash Serial Test Interface features are disabled. Once set,
this bit can be reset only by an external hardware ERASE request to the chip. Refer to the product definition sec-
tion for the pin name that controls the ERASE. In this case, the full memory plane is erased and all lock and
general-purpose NVM bits are cleared. The security bit in the MC_FSR is cleared only after these operations. The
activation sequence is:
• Start the Set Security Bit command (SSB) by writing the Flash Command Register.
• When the locking completes, the bit FRDY in the Flash Programming Status Register (MC_FSR) rises. If an
interrupt has been enabled by setting the bit FRDY in MC_FMR, the interrupt line of the Memory Controller is
activated.
When the security bit is active, the SECURITY bit in the MC_FSR is set.
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19.3 Embedded Flash Controller (EFC) User Interface
The User Interface of the EFC is integrated within the Memory Controller with Base Address: 0xFFFF FF00.
The SAM7S512 is equipped with two EFCs, EFC0 and EFC1, as described in the Register Mapping tables and Register
descriptions that follow.
Table 19-3. (EFC0) Register Mapping
Offset Register Name Access Reset
0x60 MC Flash Mode Register MC_FMR Read-write 0x0
0x64 MC Flash Command Register MC_FCR Write-only –
0x68 MC Flash Status Register MC_FSR Read-only –
0x6C Reserved – – –
Table 19-4. (EFC1) Register Mapping
Offset Register Name Access Reset
0x70 MC Flash Mode Register MC_FMR Read-write 0x0
0x74 MC Flash Command Register MC_FCR Write-only –
0x78 MC Flash Status Register MC_FSR Read-only –
0x7C Reserved – – –
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19.3.1 MC Flash Mode Register
Register Name:MC_FMR
Access Type: Read-write
Offset: (EFC0) 0x60
Offset: (EFC1) 0x70
• FRDY: Flash Ready Interrupt Enable
0: Flash Ready does not generate an interrupt.
1: Flash Ready generates an interrupt.
• LOCKE: Lock Error Interrupt Enable
0: Lock Error does not generate an interrupt.
1: Lock Error generates an interrupt.
• PROGE: Programming Error Interrupt Enable
0: Programming Error does not generate an interrupt.
1: Programming Error generates an interrupt.
• NEBP: No Erase Before Programming
0: A page erase is performed before programming.
1: No erase is performed before programming.
• FWS: Flash Wait State
This field defines the number of wait states for read and write operations:
• FMCN: Flash Microsecond Cycle Number
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
FMCN
15 14 13 12 11 10 9 8
–––––– FWS
76543210
NEBP – – – PROGE LOCKE – FRDY
FWS Read Operations Write Operations
0 1 cycle 2 cycles
1 2 cycles 3 cycles
2 3 cycles 4 cycles
3 4 cycles 4 cycles
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Before writing Non Volatile Memory bits (Lock bits, General Purpose NVM bit and Security bits), this field must be set to the
number of Master Clock cycles in one microsecond.
When writing the rest of the Flash, this field defines the number of Master Clock cycles in 1.5 microseconds. This number
must be rounded up.
Warning: The value 0 is only allowed for a master clock period superior to 30 microseconds.
Warning: In order to guarantee valid operations on the flash memory, the field Flash Microsecond Cycle Number (FMCN)
must be correctly programmed.
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19.3.2 MC Flash Command Register
Register Name:MC_FCR
Access Type: Write-only
Offset: (EFC0) 0x64
Offset: (EFC1) 0x74
• FCMD: Flash Command
This field defines the Flash commands:
31 30 29 28 27 26 25 24
KEY
23 22 21 20 19 18 17 16
–––––– PAGEN
15 14 13 12 11 10 9 8
PAG E N
76543210
–––– FCMD
FCMD Operations
0000 No command.
Does not raise the Programming Error Status flag in the Flash Status Register MC_FSR.
0001 Write Page Command (WP):
Starts the programming of the page specified in the PAGEN field.
0010 Set Lock Bit Command (SLB):
Starts a set lock bit sequence of the lock region specified in the PAGEN field.
0011
Write Page and Lock Command (WPL):
The lock sequence of the lock region associated with the page specified in the field PAGEN
occurs automatically after completion of the programming sequence.
0100 Clear Lock Bit Command (CLB):
Starts a clear lock bit sequence of the lock region specified in the PAGEN field.
1000
Erase All Command (EA):
Starts the erase of the entire Flash.
If at least one page is locked, the command is cancelled.
1011
Set General-purpose NVM Bit (SGPB):
Activates the general-purpose NVM bit corresponding to the number specified in the PAGEN
field.
1101
Clear General Purpose NVM Bit (CGPB):
Deactivates the general-purpose NVM bit corresponding to the number specified in the
PAGEN field.
1111 Set Security Bit Command (SSB):
Sets security bit.
Others Reserved.
Raises the Programming Error Status flag in the Flash Status Register MC_FSR.
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•PAGEN: Page Number
Note: Depending on the command, all the possible unused bits of PAGEN are meaningless.
• KEY: Write Protection Key
This field should be written with the value 0x5A to enable the command defined by the bits of the register. If the field is writ-
ten with a different value, the write is not performed and no action is started.
Command PAGEN Description
Write Page Command PAGEN defines the page number to be written.
Write Page and Lock Command PAGEN defines the page number to be written and its associated
lock region.
Erase All Command This field is meaningless
Set/Clear Lock Bit Command PAGEN defines one page number of the lock region to be locked or
unlocked.
Set/Clear General Purpose NVM Bit Command PAGEN defines the general-purpose bit number.
Set Security Bit Command This field is meaningless
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19.3.3 MC Flash Status Register
Register Name:MC_FSR
Access Type: Read-only
Offset: (EFC0) 0x68
Offset: (EFC1) 0x78
• FRDY: Flash Ready Status
0: The EFC is busy and the application must wait before running a new command.
1: The EFC is ready to run a new command.
• LOCKE: Lock Error Status
0: No programming of at least one locked lock region has happened since the last read of MC_FSR.
1: Programming of at least one locked lock region has happened since the last read of MC_FSR.
• PROGE: Programming Error Status
0: No invalid commands and no bad keywords were written in the Flash Command Register MC_FCR.
1: An invalid command and/or a bad keyword was/were written in the Flash Command Register MC_FCR.
• SECURITY: Security Bit Status (Does not apply to EFC1 on the SAM7S512.)
0: The security bit is inactive.
1: The security bit is active.
• GPNVMx: General-purpose NVM Bit Status (Does not apply to EFC1 on the SAM7S512.)
0: The corresponding general-purpose NVM bit is inactive.
1: The corresponding general-purpose NVM bit is active.
• EFC LOCKSx: Lock Region x Lock Status
0: The corresponding lock region is not locked.
1: The corresponding lock region is locked.
LOCKS 8-15 do not apply to SAM7S128/321/32/161/16.
31 30 29 28 27 26 25 24
LOCKS15 LOCKS14 LOCKS13 LOCKS12 LOCKS11 LOCKS10 LOCKS9 LOCKS8
23 22 21 20 19 18 17 16
LOCKS7 LOCKS6 LOCKS5 LOCKS4 LOCKS3 LOCKS2 LOCKS1 LOCKS0
15 14 13 12 11 10 9 8
– – – – – – GPNVM1 GPNVM0
76543210
– – – SECURITY PROGE LOCKE – FRDY
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MC_FSR, LOCKSx Product Specific Map
The SAM7S512 manages 16 lock bits on EF0 and 16 on EFC1 = 32.
SAM7S512 SAM7S256 SAM7S128 SAM7S64 SAM7S321 SAM7S32 SAM7S161 SAM7S16 Denomination
32() 168168 8 8 8
Number of Lock
Bits
LOCKS0 LOCKS0 LOCKS0 LOCKS0 LOCKS0 LOCKS0 LOCKS0 LOCKS0 Lock Region 0
Lock Status
LOCKS1 LOCKS1 LOCKS1 LOCKS1 LOCKS1 LOCKS1 LOCKS1 LOCKS1 Lock Region 1
Lock Status
LOCKS2 LOCKS2 LOCKS2 LOCKS2 LOCKS2 LOCKS2 LOCKS2 LOCKS2 Lock Region 2
Lock Status
LOCKS3 LOCKS3 LOCKS3 LOCKS3 LOCKS3 LOCKS3 LOCKS3 LOCKS3 Lock Region 3
Lock Status
LOCKS4 LOCKS4 LOCKS4 LOCKS4 LOCKS4 LOCKS4 LOCKS4 LOCKS4 Lock Region 4
Lock Status
LOCKS5 LOCKS5 LOCKS5 LOCKS5 LOCKS5 LOCKS5 LOCKS5 LOCKS5 Lock Region 5
Lock Status
LOCKS6 LOCKS6 LOCKS6 LOCKS6 LOCKS6 LOCKS6 LOCKS6 LOCKS6 Lock Region 6
Lock Status
LOCKS7 LOCKS7 LOCKS7 LOCKS7 LOCKS7 LOCKS7 LOCKS7 LOCKS7 Lock Region 7
Lock Status
LOCKS8 LOCKS8 – LOCKS8 – – – – Lock Region 8
Lock Status
LOCKS9 LOCKS9 – LOCKS9 – – – – Lock Region 9
Lock Status
LOCKS10 LOCKS10 – LOCKS10 – – – – Lock Region 10
Lock Status
LOCKS11 LOCKS11 – LOCKS11 – – – – Lock Region 11
Lock Status
LOCKS12 LOCKS12 – LOCKS12 – – – – Lock Region 12
Lock Status
LOCKS13 LOCKS13 – LOCKS13 – – – – Lock Region 13
Lock Status
LOCKS14 LOCKS14 – LOCKS14 – – – – Lock Region 14
Lock Status
LOCKS15 LOCKS15 – LOCKS15 – – – – Lock Region 15
Lock Status
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20. Fast Flash Programming Interface (FFPI)
20.1 Overview
The Fast Flash Programming Interface provides two solutions - parallel or serial - for high-volume programming
using a standard gang programmer. The parallel interface is fully handshaked and the device is considered to be a
standard EEPROM. Additionally, the parallel protocol offers an optimized access to all the embedded Flash func-
tionalities. The serial interface uses the standard IEEE 1149.1 JTAG protocol. It offers an optimized access to all
the embedded Flash functionalities.
Although the Fast Flash Programming Mode is a dedicated mode for high volume programming, this mode is not
designed for in-situ programming.
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20.2 Parallel Fast Flash Programming
20.2.1 Device Configuration
In Fast Flash Programming Mode, the device is in a specific test mode. Only a certain set of pins is significant.
Other pins must be left unconnected.
Figure 20-1. SAM7S512/256/128/64/321/161 Parallel Programming Interface
Figure 20-2. SAM7S32/16 Parallel Programming Interface
NCMD PGMNCMD
RDY PGMRDY
NOE PGMNOE
NVALID PGMNVALID
MODE[3:0] PGMM[3:0]
DATA[15:0] PGMD[15:0]
XIN
TST
VDDIO
PGMEN0
PGMEN1
0 - 50MHz
VDDIO
VDDCORE
VDDIO
VDDPLL
VDDFLASH
GND
GND
VDDIO
PGMEN2
NCMD PGMNCMD
RDY PGMRDY
NOE PGMNOE
NVALID PGMNVALID
MODE[3:0] PGMM[3:0]
DATA[7:0] PGMD[7:0]
XIN
TST
VDDIO
PGMEN0
PGMEN1
0 - 50MHz
VDDIO
VDDCORE
VDDIO
VDDPLL
VDDFLASH
GND
GND
VDDIO
PGMEN2
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Notes: 1. DATA[7:0] pertains to the SAM7S32/16.
2. PGMD[7:0] pertains to the SAM7S32/16.
Table 20-1. Signal Description List
Signal Name Function Type
Active
Level Comments
Power
VDDFLASH Flash Power Supply Power
VDDIO I/O Lines Power Supply Power
VDDCORE Core Power Supply Power
VDDPLL PLL Power Supply Power
GND Ground Ground
Clocks
XIN
Main Clock Input.
This input can be tied to GND. In this case, the
device is clocked by the internal RC oscillator.
Input 32KHz to 50MHz
Test
TST Test Mode Select Input High Must be connected to VDDIO
PGMEN0 Test Mode Select Input High Must be connected to VDDIO
PGMEN1 Test Mode Select Input High Must be connected to VDDIO
PGMEN2 Test Mode Select Input Low Must be connected to GND
PIO
PGMNCMD Valid command available Input Low Pulled-up input at reset
PGMRDY 0: Device is busy
1: Device is ready for a new command Output High Pulled-up input at reset
PGMNOE Output Enable (active high) Input Low Pulled-up input at reset
PGMNVALID 0: DATA[15:0] or DATA[7:0](1) is in input mode
1: DATA[15:0] or DATA[7:0](1) is in output mode Output Low Pulled-up input at reset
PGMM[3:0] Specifies DATA type (See Table 20-2) Input Pulled-up input at reset
PGMD[15:0] or [7:0](2) Bi-directional data bus Input/Output Pulled-up input at reset
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20.2.2 Signal Names
Depending on the MODE settings, DATA is latched in different internal registers.
When MODE is equal to CMDE, then a new command (strobed on DATA[15:0] or DATA[7:0] signals) is stored in
the command register.
Note: DATA[7:0] pertains to the SAM7S32/16.
Notes: 1. DATA[7:0] pertains to the SAM7S32/16.
2. Applies to SAM7S512.
Table 20-2. Mode Coding
MODE[3:0] Symbol Data
0000 CMDE Command Register
0001 ADDR0 Address Register LSBs
0010 ADDR1
0011 ADDR2
0100 ADDR3 Address Register MSBs
0101 DATA Data Register
Default IDLE No register
Table 20-3. Command Bit Coding
DATA[15:0]
DATA[7:0](1) Symbol Command Executed
0x0011 READ Read Flash
0x0012 WP Write Page Flash
0x0022 WPL Write Page and Lock Flash
0x0032 EWP Erase Page and Write Page
0x0042 EWPL Erase Page and Write Page then Lock
0x0013 EA Erase All
0x0014 SLB Set Lock Bit
0x0024 CLB Clear Lock Bit
0x0015 GLB Get Lock Bit
0x0034 SGPB Set General Purpose NVM bit
0x0044 CGPB Clear General Purpose NVM bit
0x0025 GGPB Get General Purpose NVM bit
0x0054 SSE Set Security Bit
0x0035 GSE Get Security Bit
0x001F WRAM Write Memory
0x0016 SEFC Select EFC Controller(2)
0x001E GVE Get Version
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20.2.3 Entering Programming Mode
The following algorithm puts the device in Parallel Programming Mode:
• Apply GND, VDDIO, VDDCORE, VDDFLASH and VDDPLL.
• Apply XIN clock within TPOR_RESET if an external clock is available.
•Wait for T
POR_RESET
• Start a read or write handshaking.
Note: After reset, the device is clocked by the internal RC oscillator. Before clearing RDY signal, if an external clock (> 32
kHz) is connected to XIN, then the device switches on the external clock. Else, XIN input is not considered. A higher
frequency on XIN speeds up the programmer handshake.
20.2.4 Programmer Handshaking
An handshake is defined for read and write operations. When the device is ready to start a new operation (RDY
signal set), the programmer starts the handshake by clearing the NCMD signal. The handshaking is achieved once
NCMD signal is high and RDY is high.
20.2.4.1 Write Handshaking
For details on the write handshaking sequence, refer to Figure 20-3, Figure 20-4 and Table 20-4.
Figure 20-3. SAM7S512/256/128/64/321/161Parallel Programming Timing, Write Sequence
Figure 20-4. SAM7S32/16 Parallel Programming Timing, Write Sequence
NCMD
RDY
NOE
NVALID
DATA[15:0]
MODE[3:0]
1
2
3
4
5
NCMD
RDY
NOE
NVALID
DATA[7:0]
MODE[3:0]
1
2
3
4
5
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20.2.4.2 Read Handshaking
For details on the read handshaking sequence, refer to Figure 20-5, Figure 20-6 and Table 20-5.
Figure 20-5. SAM7S542/256/128/321/161 Parallel Programming Timing, Read Sequence
Figure 20-6. SAM7S32/16 Parallel Programming Timing, Read Sequence
Table 20-4. Write Handshake
Step Programmer Action Device Action Data I/O
1 Sets MODE and DATA signals Waits for NCMD low Input
2 Clears NCMD signal Latches MODE and DATA Input
3 Waits for RDY low Clears RDY signal Input
4 Releases MODE and DATA signals Executes command and polls NCMD high Input
5 Sets NCMD signal Executes command and polls NCMD high Input
6 Waits for RDY high Sets RDY Input
NCMD
RDY
NOE
NVALID
DATA[15:0]
MODE[3:0]
1
2
3
4
5
6
7
9
8
ADDR
Adress IN Z Data OUT
10
11
XIN
12
13
NCMD
RDY
NOE
NVALID
DATA[7:0]
MODE[3:0]
1
2
3
4
5
6
7
9
8
ADDR
Adress IN Z Data OUT
10
11
XIN
12
13
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Table 20-5. Read Handshake
Step Programmer Action Device Action DATA I/O
1 Sets MODE and DATA signals Waits for NCMD low Input
2 Clears NCMD signal Latch MODE and DATA Input
3 Waits for RDY low Clears RDY signal Input
4 Sets DATA signal in tristate Waits for NOE Low Input
5 Clears NOE signal Tr i s t a t e
6 Waits for NVALID low Sets DATA bus in output mode and outputs the
flash contents. Output
7 Clears NVALID signal Output
8 Reads value on DATA Bus Waits for NOE high Output
9 Sets NOE signal Output
10 Waits for NVALID high Sets DATA bus in input mode X
11 Sets DATA in output mode Sets NVALID signal Input
12 Sets NCMD signal Waits for NCMD high Input
13 Waits for RDY high Sets RDY signal Input
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20.2.5 Device Operations
Several commands on the Flash memory are available. These commands are summarized in Table 20-3 on page
126. Each command is driven by the programmer through the parallel interface running several read/write hand-
shaking sequences.
When a new command is executed, the previous one is automatically achieved. Thus, chaining a read command
after a write automatically flushes the load buffer in the Flash.
In the following tables, 21-6 through 21-18
• DATA[15:0] pertains to SAM7S512/256/128/64/321/161
• DATA[7:0] pertains to SAM7S32/16
20.2.5.1 Flash Read Command
This command is used to read the contents of the Flash memory. The read command can start at any valid
address in the memory plane and is optimized for consecutive reads. Read handshaking can be chained; an inter-
nal address buffer is automatically increased.
Table 20-6. Read Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE READ
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Read handshaking DATA *Memory Address++
5 Read handshaking DATA *Memory Address++
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
n+2 Read handshaking DATA *Memory Address++
n+3 Read handshaking DATA *Memory Address++
... ... ... ...
Table 20-7. Read Command
Step Handshake Sequence MODE[3:0] DATA[7:0]
1 Write handshaking CMDE READ
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Write handshaking ADDR2 Memory Address
5 Write handshaking ADDR3 Memory Address
6 Read handshaking DATA *Memory Address++
7 Read handshaking DATA *Memory Address++
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
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20.2.5.2 Flash Write Command
This command is used to write the Flash contents.
The Flash memory plane is organized into several pages. Data to be written are stored in a load buffer that corre-
sponds to a Flash memory page. The load buffer is automatically flushed to the Flash:
• before access to any page other than the current one
• when a new command is validated (MODE = CMDE)
The Write Page command (WP) is optimized for consecutive writes. Write handshaking can be chained; an inter-
nal address buffer is automatically increased.
n+2 Write handshaking ADDR2 Memory Address
n+3 Write handshaking ADDR3 Memory Address
n+4 Read handshaking DATA *Memory Address++
n+5 Read handshaking DATA *Memory Address++
... ... ... ...
Table 20-7. Read Command (Continued)
Step Handshake Sequence MODE[3:0] DATA[7:0]
Table 20-8. Write Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE WP or WPL or EWP or EWPL
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Write handshaking DATA *Memory Address++
5 Write handshaking DATA *Memory Address++
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
n+2 Write handshaking DATA *Memory Address++
n+3 Write handshaking DATA *Memory Address++
... ... ... ...
Table 20-9. Write Command
Step Handshake Sequence MODE[3:0] DATA[7:0]
1 Write handshaking CMDE WP or WPL or EWP or EWPL
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Write handshaking ADDR2 Memory Address
5 Write handshaking ADDR3 Memory Address
6 Write handshaking DATA *Memory Address++
7 Write handshaking DATA *Memory Address++
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The Flash command Write Page and Lock (WPL) is equivalent to the Flash Write Command. However, the lock
bit is automatically set at the end of the Flash write operation. As a lock region is composed of several pages, the
programmer writes to the first pages of the lock region using Flash write commands and writes to the last page of
the lock region using a Flash write and lock command.
The Flash command Erase Page and Write (EWP) is equivalent to the Flash Write Command. However, before
programming the load buffer, the page is erased.
The Flash command Erase Page and Write the Lock (EWPL) combines EWP and WPL commands.
20.2.5.3 Flash Full Erase Command
This command is used to erase the Flash memory planes.
All lock regions must be unlocked before the Full Erase command by using the CLB command. Otherwise, the
erase command is aborted and no page is erased.
20.2.5.4 Flash Lock Commands
Lock bits can be set using WPL or EWPL commands. They can also be set by using the Set Lock command
(SLB). With this command, several lock bits can be activated. A Bit Mask is provided as argument to the com-
mand. When bit 0 of the bit mask is set, then the first lock bit is activated.
In the same way, the Clear Lock command (CLB) is used to clear lock bits. All the lock bits are also cleared by the
EA command.
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
n+2 Write handshaking ADDR2 Memory Address
n+3 Write handshaking ADDR3 Memory Address
n+4 Write handshaking DATA *Memory Address++
n+5 Write handshaking DATA *Memory Address++
... ... ... ...
Table 20-9. Write Command (Continued)
Step Handshake Sequence MODE[3:0] DATA[7:0]
Table 20-10. Full Erase Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE EA
2 Write handshaking DATA 0
Table 20-11. Set and Clear Lock Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE SLB or CLB
2 Write handshaking DATA Bit Mask
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Lock bits can be read using Get Lock Bit command (GLB). The nth lock bit is active when the bit n of the bit mask
is set..
20.2.5.5 Flash General-purpose NVM Commands
General-purpose NVM bits (GP NVM bits) can be set using the Set GPNVM command (SGPB). This command
also activates GP NVM bits. A bit mask is provided as argument to the command. When bit 0 of the bit mask is set,
then the first GP NVM bit is activated.
In the same way, the Clear GPNVM command (CGPB) is used to clear general-purpose NVM bits. All the general-
purpose NVM bits are also cleared by the EA command. The general-purpose NVM bit is deactivated when the
corresponding bit in the pattern value is set to 1.
General-purpose NVM bits can be read using the Get GPNVM Bit command (GGPB). The nth GP NVM bit is active
when bit n of the bit mask is set..
20.2.5.6 Flash Security Bit Command
A security bit can be set using the Set Security Bit command (SSE). Once the security bit is active, the Fast Flash
programming is disabled. No other command can be run. An event on the Erase pin can erase the security bit once
the contents of the Flash have been erased.
The SAM7S512 security bit is controlled by the EFC0. To use the Set Security Bit command, the EFC0 must be
selected using the Select EFC command
Once the security bit is set, it is not possible to access FFPI. The only way to erase the security bit is to erase the
Flash.
In order to erase the Flash, the user must perform the following:
Table 20-12. Get Lock Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE GLB
2 Read handshaking DATA
Lock Bit Mask Status
0 = Lock bit is cleared
1 = Lock bit is set
Table 20-13. Set/Clear GP NVM Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE SGPB or CGPB
2 Write handshaking DATA GP NVM bit pattern value
Table 20-14. Get GP NVM Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE GGPB
2 Read handshaking DATA
GP NVM Bit Mask Status
0 = GP NVM bit is cleared
1 = GP NVM bit is set
Table 20-15. Set Security Bit Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SSE
2 Write handshaking DATA 0
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• Power-off the chip
• Power-on the chip with TST = 0
• Assert Erase during a period of more than 220 ms
• Power-off the chip
Then it is possible o return to FFPI mode and check that Flash is erased.
20.2.5.7 SAM7S512 Select EFC Command
The commands WPx, EA, xLB, xFB are executed using the current EFC controller. The default EFC controller is
EFC0. The Select EFC command (SEFC) allows selection of the current EFC controller.
20.2.5.8 Memory Write Command
This command is used to perform a write access to any memory location.
The Memory Write command (WRAM) is optimized for consecutive writes. Write handshaking can be chained; an
internal address buffer is automatically increased.
Table 20-16. Select EFC Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SEFC
2 Write handshaking DATA 0 = Select EFC0
1 = Select EFC1
Table 20-17. Write Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE WRAM
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Write handshaking DATA *Memory Address++
5 Write handshaking DATA *Memory Address++
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
n+2 Write handshaking DATA *Memory Address++
n+3 Write handshaking DATA *Memory Address++
... ... ... ...
Table 20-18. Write Command
Step Handshake Sequence MODE[3:0] DATA[7:0]
1 Write handshaking CMDE WRAM
2 Write handshaking ADDR0 Memory Address LSB
3 Write handshaking ADDR1 Memory Address
4 Write handshaking ADDR2 Memory Address
5 Write handshaking ADDR3 Memory Address
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20.2.5.9 Get Version Command
The Get Version (GVE) command retrieves the version of the FFPI interface.
6 Write handshaking DATA *Memory Address++
7 Write handshaking DATA *Memory Address++
... ... ... ...
n Write handshaking ADDR0 Memory Address LSB
n+1 Write handshaking ADDR1 Memory Address
n+2 Write handshaking ADDR2 Memory Address
n+3 Write handshaking ADDR3 Memory Address
n+4 Write handshaking DATA *Memory Address++
n+5 Write handshaking DATA *Memory Address++
... ... ... ...
Table 20-18. Write Command (Continued)
Step Handshake Sequence MODE[3:0] DATA[7:0]
Table 20-19. Get Version Command
Step Handshake Sequence MODE[3:0] DATA[15:0] or DATA[7:0]
1 Write handshaking CMDE GVE
2 Write handshaking DATA Version
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20.3 Serial Fast Flash Programming
The Serial Fast Flash programming interface is based on IEEE Std. 1149.1 “Standard Test Access Port and
Boundary-Scan Architecture”. Refer to this standard for an explanation of terms used in this chapter and for a
description of the TAP controller states.
In this mode, data read/written from/to the embedded Flash of the device are transmitted through the JTAG inter-
face of the device.
20.3.1 Device Configuration
In Serial Fast Flash Programming Mode, the device is in a specific test mode. Only a distinct set of pins is signifi-
cant. Other pins must be left unconnected.
Figure 20-7. Serial Programming
TDI
TDO
TMS
TCK
XIN
TST
VDDIO
PGMEN0
PGMEN1
0-50MHz
VDDIO
VDDCORE
VDDIO
VDDPLL
VDDFLASH
GND
VDDIO
GND PGMEN2
Table 20-20. Signal Description List
Signal Name Function Type
Active
Level Comments
Power
VDDFLASH Flash Power Supply Power
VDDIO I/O Lines Power Supply Power
VDDCORE Core Power Supply Power
VDDPLL PLL Power Supply Power
GND Ground Ground
Clocks
XIN
Main Clock Input.
This input can be tied to GND. In this
case, the device is clocked by the internal
RC oscillator.
Input 32 kHz to 50 MHz
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20.3.2 Entering Serial Programming Mode
The following algorithm puts the device in Serial Programming Mode:
• Apply GND, VDDIO, VDDCORE, VDDFLASH and VDDPLL.
• Apply XIN clock within TPOR_RESET + 32(TSCLK) if an external clock is available.
•Wait for T
POR_RESET
.
• Reset the TAP controller clocking 5 TCK pulses with TMS set.
• Shift 0x2 into the IR register (IR is 4 bits long, LSB first) without going through the Run-Test-Idle state.
• Shift 0x2 into the DR register (DR is 4 bits long, LSB first) without going through the Run-Test-Idle state.
• Shift 0xC into the IR register (IR is 4 bits long, LSB first) without going through the Run-Test-Idle state.
Note: After reset, the device is clocked by the internal RC oscillator. Before clearing RDY signal, if an external clock (> 32
kHz) is connected to XIN, then the device will switch on the external clock. Else, XIN input is not considered. An higher
frequency on XIN speeds up the programmer handshake.
20.3.3 Read/Write Handshake
The read/write handshake is done by carrying out read/write operations on two registers of the device that are
accessible through the JTAG:
• Debug Comms Control Register: DCCR
• Debug Comms Data Register: DCDR
Test
TST Test Mode Select Input High Must be connected to VDDIO.
PGMEN0 Test Mode Select Input High Must be connected to VDDIO
PGMEN1 Test Mode Select Input High Must be connected to VDDIO
PGMEN2 Test Mode Select Input Low Must be connected to GND
JTAG
TCK JTAG TCK Input - Pulled-up input at reset
TDI JTAG Test Data In Input - Pulled-up input at reset
TDO JTAG Test Data Out Output -
TMS JTAG Test Mode Select Input - Pulled-up input at reset
Table 20-20. Signal Description List (Continued)
Signal Name Function Type
Active
Level Comments
Table 20-21. Reset TAP Controller and Go to Select-DR-Scan
TDI TMS TAP Controller State
X1
X1
X1
X1
X 1 Test-Logic Reset
X 0 Run-Test/Idle
Xt 1 Select-DR-Scan
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Access to these registers is done through the TAP 38-bit DR register comprising a 32-bit data field, a 5-bit address
field and a read/write bit. The data to be written is scanned into the 32-bit data field with the address of the register
to the 5-bit address field and 1 to the read/write bit. A register is read by scanning its address into the address field
and 0 into the read/write bit, going through the UPDATE-DR TAP state, then scanning out the data.
Refer to the ARM7TDMI reference manuel for more information on Comm channel operations.
Figure 20-8. TAP 8-bit DR Register
A read or write takes place when the TAP controller enters UPDATE-DR state. Refer to the IEEE 1149.1 for more
details on JTAG operations.
• The address of the Debug Comms Control Register is 0x04.
• The address of the Debug Comms Data Register is 0x05.
The Debug Comms Control Register is read-only and allows synchronized handshaking between the processor
and the debugger.
– Bit 1 (W): Denotes whether the programmer can read a data through the Debug Comms Data Register.
If the device is busy W = 0, then the programmer must poll until W = 1.
– Bit 0 (R): Denotes whether the programmer can send data from the Debug Comms Data Register. If R
= 1, data previously placed there through the scan chain has not been collected by the device and so
the programmer must wait.
The write handshake is done by polling the Debug Comms Control Register until the R bit is cleared. Once cleared,
data can be written to the Debug Comms Data Register.
The read handshake is done by polling the Debug Comms Control Register until the W bit is set. Once set, data
can be read in the Debug Comms Data Register.
20.3.4 Device Operations
Several commands on the Flash memory are available. These commands are summarized in Table 20-3 on page
126. Commands are run by the programmer through the serial interface that is reading and writing the Debug
Comms Registers.
TDI TDO
40
r/w Address 31 Data 0
Address
Decoder
Debug Comms Control Register
Debug Comms Data Register
32
5
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20.3.4.1 Flash Read Command
This command is used to read the Flash contents. The memory map is accessible through this command. Memory
is seen as an array of words (32-bit wide). The read command can start at any valid address in the memory plane.
This address must be word-aligned. The address is automatically incremented.
20.3.4.2 Flash Write Command
This command is used to write the Flash contents. The address transmitted must be a valid Flash address in the
memory plane.
The Flash memory plane is organized into several pages. Data to be written is stored in a load buffer that corre-
sponds to a Flash memory page. The load buffer is automatically flushed to the Flash:
• before access to any page than the current one
• at the end of the number of words transmitted
The Write Page command (WP) is optimized for consecutive writes. Write handshaking can be chained; an inter-
nal address buffer is automatically increased.
Flash Write Page and Lock command (WPL) is equivalent to the Flash Write Command. However, the lock bit is
automatically set at the end of the Flash write operation. As a lock region is composed of several pages, the pro-
grammer writes to the first pages of the lock region using Flash write commands and writes to the last page of the
lock region using a Flash write and lock command.
Flash Erase Page and Write command (EWP) is equivalent to the Flash Write Command. However, before pro-
gramming the load buffer, the page is erased.
Flash Erase Page and Write the Lock command (EWPL) combines EWP and WPL commands.
20.3.4.3 Flash Full Erase Command
This command is used to erase the Flash memory planes.
Table 20-22. Read Command
Read/Write DR Data
Write (Number of Words to Read) << 16 | READ
Write Address
Read Memory [address]
Read Memory [address+4]
... ...
Read Memory [address+(Number of Words to Read - 1)* 4]
Table 20-23. Write Command
Read/Write DR Data
Write (Number of Words to Write) << 16 | (WP or WPL or EWP or EWPL)
Write Address
Write Memory [address]
Write Memory [address+4]
Write Memory [address+8]
Write Memory [address+(Number of Words to Write - 1)* 4]
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All lock bits must be deactivated before using the Full Erase command. This can be done by using the CLB
command.
20.3.4.4 Flash Lock Commands
Lock bits can be set using WPL or EWPL commands. They can also be set by using the Set Lock command
(SLB). With this command, several lock bits can be activated at the same time. Bit 0 of Bit Mask corresponds to the
first lock bit and so on.
In the same way, the Clear Lock command (CLB) is used to clear lock bits. All the lock bits can also be cleared by
the EA command.
Lock bits can be read using Get Lock Bit command (GLB). When a bit set in the Bit Mask is returned, then the cor-
responding lock bit is active.
20.3.4.5 Flash General-purpose NVM Commands
General-purpose NVM bits (GP NVM) can be set with the Set GPNVM command (SGPB). Using this command,
several GP NVM bits can be activated at the same time. Bit 0 of Bit Mask corresponds to the first GPNVM bit and
so on.
In the same way, the Clear GPNVM command (CGPB) is used to clear GP NVM bits. All the general-purpose NVM
bits are also cleared by the EA command.
GP NVM bits can be read using Get GPNVM Bit command (GGPB). When a bit set in the Bit Mask is returned,
then the corresponding GPNVM bit is set.
Table 20-24. Full Erase Command
Read/Write DR Data
Write EA
Table 20-25. Set and Clear Lock Bit Command
Read/Write DR Data
Write SLB or CLB
Write Bit Mask
Table 20-26. Get Lock Bit Command
Read/Write DR Data
Write GLB
Read Bit Mask
Table 20-27. Set and Clear General-purpose NVM Bit Command
Read/Write DR Data
Write SGPB or CGPB
Write Bit Mask
Table 20-28. Get General-purpose NVM Bit Command
Read/Write DR Data
Write GGPB
Read Bit Mask
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20.3.4.6 Flash Security Bit Command
Security bits can be set using Set Security Bit command (SSE). Once the security bit is active, the Fast Flash pro-
gramming is disabled. No other command can be run. Only an event on the Erase pin can erase the security bit
once the contents of the Flash have been erased.
The SAM7S512 security bit is controlled by the EFC0. To use the Set Security Bit command, the EFC0 must be
selected using the Select EFC command.
Once the security bit is set, it is not possible to access FFPI. The only way to erase the security bit is to erase the
Flash.
In order to erase the Flash, the user must perform the following:
• Power-off the chip
• Power-on the chip with TST = 0
• Assert Erase during a period of more than 220 ms
• Power-off the chip
Then it is possible to return to FFPI mode and check that Flash is erased.
20.3.4.7 SAM7S512 Select EFC Command
The commands WPx, EA, xLB, xFB are executed using the current EFC controller. The default EFC controller is
EFC0. The Select EFC command (SEFC) allows selection of the current EFC controller.
Table 20-29. Set Security Bit Command
Read/Write DR Data
Write SSE
Table 20-30. Select EFC Command
Step Handshake Sequence MODE[3:0] DATA[15:0]
1 Write handshaking CMDE SEFC
2 Write handshaking DATA 0 = Select EFC0
1 = Select EFC1
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20.3.4.8 Memory Write Command
This command is used to perform a write access to any memory location.
The Memory Write command (WRAM) is optimized for consecutive writes. An internal address buffer is automati-
cally increased.
20.3.4.9 Get Version Command
The Get Version (GVE) command retrieves the version of the FFPI interface.
Table 20-31. Write Command
Read/Write DR Data
Write (Number of Words to Write) << 16 | (WRAM)
Write Address
Write Memory [address]
Write Memory [address+4]
Write Memory [address+8]
Write Memory [address+(Number of Words to Write - 1)* 4]
Table 20-32. Get Version Command
Read/Write DR Data
Write GVE
Read Version
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21. SAM7 Boot Program
21.1 Description
The Boot Program integrates different programs permitting download and/or upload into the different memories of
the product.
First, it initializes the Debug Unit serial port (DBGU) and the USB Device Port.
SAM-BA® Boot is then executed. It waits for transactions either on the USB device or on the DBGU serial port.
21.2 Flow Diagram
The Boot Program implements the algorithm shown in Figure 21-1 or Figure 21-2.
Figure 21-1. Boot Program Algorithm Flow Diagram with USB
Figure 21-2. Boot Program Algorithm Flow Diagram without USB
Device
Setup
AutoBaudrate
Sequence Successful ?
Run SAM-BA Boot Run SAM-BA Boot
USB Enumeration
Successful ?
Yes Yes
No
No
Device
Setup Run SAM-BA Boot
AutoBaudrate
Sequence Successful ?
Yes
No
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21.3 Device Initialization with USB
Initialization follows the steps described below:
1. FIQ initialization
1. Stack setup for ARM supervisor mode
2. Setup the Embedded Flash Controller
3. External Clock detection
4. Main oscillator frequency detection if no external clock detected
5. Switch Master Clock on Main Oscillator
6. Copy code into SRAM
7. C variable initialization
8. PLL setup: PLL is initialized to generate a 48 MHz clock necessary to use the USB Device
9. Disable of the Watchdog and enable of the user reset
10. Initialization of the USB Device Port
11. Jump to SAM-BA Boot sequence (see “SAM-BA Boot” on page 145)
21.4 Device Initialization without USB
Initialization follows the steps described below:
1. FIQ initialization
1. Stack setup for ARM supervisor mode
2. Setup the Embedded Flash Controller
3. External Clock detection
4. Main oscillator frequency detection if no external clock detected
5. Switch Master Clock on Main Oscillator
6. Copy code into SRAM
7. C variable initialization
8. PLL setup: PLL is initialized to generate a 48 MHz clock
9. Disable of the Watchdog and enable of the user reset
10. Jump to SAM-BA Boot sequence (see “SAM-BA Boot” below)
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21.5 SAM-BA Boot
The SAM-BA boot principle is to:
– Check if USB Device enumeration has occurred
– Check if the Auto Baudrate sequence has succeeded (see Figure 21-3)
Figure 21-3. Auto Baudrate Flow Diagram
Device
Setup
Character '0x80'
received ?
No
Ye s
Character '0x80'
received ?
No
Ye s
Character '#'
received ?
Ye s
Run SAM-BA Boot
Send Character '>'
No
1st measurement
2nd measurement
Test Communication
UART operational
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– Once the communication interface is identified, the application runs in an infinite loop waiting for
different commands as shown in Table 21-1.
• Write commands: Write a byte (O), a halfword (H) or a word (W) to the target.
–Address: Address in hexadecimal.
–Value: Byte, halfword or word to write in hexadecimal.
–Output: ‘>’.
• Read commands: Read a byte (o), a halfword (h) or a word (w) from the target.
–Address: Address in hexadecimal
–Output: The byte, halfword or word read in hexadecimal following by ‘>’
• Send a file (S): Send a file to a specified address
–Address: Address in hexadecimal
–Output: ‘>’.
Note: There is a time-out on this command which is reached when the prompt ‘>’ appears before the end of the command
execution.
• Receive a file (R): Receive data into a file from a specified address
–Address: Address in hexadecimal
–NbOfBytes: Number of bytes in hexadecimal to receive
–Output: ‘>’
•Go (G): Jump to a specified address and execute the code
–Address: Address to jump in hexadecimal
–Output: ‘>’
• Get Version (V): Return the SAM-BA boot version
–Output: ‘>’
Table 21-1. Commands Available through the SAM-BA Boot
Command Action Argument(s) Example
Owrite a byte Address, Value# O200001,CA#
oread a byte Address,# o200001,#
Hwrite a half word Address, Value# H200002,CAFE#
hread a half word Address,# h200002,#
Wwrite a word Address, Value# W200000,CAFEDECA#
wread a word Address,# w200000,#
Ssend a file Address,# S200000,#
Rreceive a file Address, NbOfBytes# R200000,1234#
Ggo Address# G200200#
Vdisplay version No argument V#
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21.5.1 DBGU Serial Port
Communication is performed through the DBGU serial port initialized to 115200 Baud, 8, n, 1.
The Send and Receive File commands use the Xmodem protocol to communicate. Any terminal performing this
protocol can be used to send the application file to the target. The size of the binary file to send depends on the
SRAM size embedded in the product. In all cases, the size of the binary file must be lower than the SRAM size
because the Xmodem protocol requires some SRAM memory to work.
21.5.2 Xmodem Protocol
The Xmodem protocol supported is the 128-byte length block. This protocol uses a two-character CRC-16 to guar-
antee detection of a maximum bit error.
Xmodem protocol with CRC is accurate provided both sender and receiver report successful transmission. Each
block of the transfer looks like:
<SOH><blk #><255-blk #><--128 data bytes--><checksum> in which:
– <SOH> = 01 hex
– <blk #> = binary number, starts at 01, increments by 1, and wraps 0FFH to 00H (not to 01)
– <255-blk #> = 1’s complement of the blk#.
– <checksum> = 2 bytes CRC16
Figure 21-4 shows a transmission using this protocol.
Figure 21-4. Xmodem Transfer Example
21.5.3 USB Device Port
A 48 MHz USB clock is necessary to use the USB Device port. It has been programmed earlier in the device initial-
ization procedure with PLLB configuration.
Host Device
SOH 01 FE Data[128] CRC CRC
C
ACK
SOH 02 FD Data[128] CRC CRC
ACK
SOH 03 FC Data[100] CRC CRC
ACK
EOT
ACK
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The device uses the USB communication device class (CDC) drivers to take advantage of the installed PC RS-232
software to talk over the USB. The CDC class is implemented in all releases of Windows®, from Windows98SE to
WindowsXP. The CDC document, available at www.usb.org, describes a way to implement devices such as ISDN
modems and virtual COM ports.
The Vendor ID is Atmel’s vendor ID 0x03EB. The product ID is 0x6124. These references are used by the host
operating system to mount the correct driver. On Windows systems, the INF files contain the correspondence
between vendor ID and product ID.
21.5.3.1 Enumeration Process
The USB protocol is a master/slave protocol. This is the host that starts the enumeration sending requests to the
device through the control endpoint. The device handles standard requests as defined in the USB Specification.
The device also handles some class requests defined in the CDC class.
Unhandled requests are STALLed.
21.5.3.2 Communication Endpoints
There are two communication endpoints and endpoint 0 is used for the enumeration process. Endpoint 1 is a 64-
byte Bulk OUT endpoint and endpoint 2 is a 64-byte Bulk IN endpoint. SAM-BA Boot commands are sent by the
host through the endpoint 1. If required, the message is split by the host into several data payloads by the host
driver.
If the command requires a response, the host can send IN transactions to pick up the response.
Table 21-2. Handled Standard Requests
Request Definition
GET_DESCRIPTOR Returns the current device configuration value.
SET_ADDRESS Sets the device address for all future device access.
SET_CONFIGURATION Sets the device configuration.
GET_CONFIGURATION Returns the current device configuration value.
GET_STATUS Returns status for the specified recipient.
SET_FEATURE Used to set or enable a specific feature.
CLEAR_FEATURE Used to clear or disable a specific feature.
Table 21-3. Handled Class Requests
Request Definition
SET_LINE_CODING Configures DTE rate, stop bits, parity and number of
character bits.
GET_LINE_CODING Requests current DTE rate, stop bits, parity and number
of character bits.
SET_CONTROL_LINE_STATE RS-232 signal used to tell the DCE device the DTE
device is now present.
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21.6 Hardware and Software Constraints
• SAM-BA boot copies itself in the SRAM and uses a block of internal SRAM for variables and stacks. The
remaining available sizes for the user codes are as follows: 57344 bytes for SAM7S512, 57344 bytes for
SAM7S256, 24576 bytes for SAM7S128, 8192 bytes for SAM7S64, 2048 bytes for SAM7S321 and SAM7S32,
3840 bytes for SAM7S161 and SAM7S16.
• USB requirements: (Does not pertain to SAM7S32/16)
– 18.432 MHz Quartz
– PIOA16 dedicated to the USB Pull-up
Table 21-4. User Area Addresses
Device Start Address End Address Size (bytes)
SAM7S512 0x202000 0x210000 57344
SAM7S256 0x202000 0x210000 57344
SAM7S128 0x202000 0x208000 24576
SAM7S64 0x202000 0x204000 8192
SAM7S321 0x202000 0x210000 2048
SAM7S32 0x201400 0x201C00 2048
SAM7S161 0x200000 0200F00 3840
SAM7S16 0x200000 0200F00 3840
Table 21-5. Pins Driven during Boot Program Execution
Peripheral Pin PIO Line
DBGU DRXD PA9
DBGU DTXD PA10
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22. Peripheral DMA Controller (PDC)
22.1 Overview
The Peripheral DMA Controller (PDC) transfers data between on-chip serial peripherals such as the UART,
USART, SSC, SPI, MCI and the on- and off-chip memories. Using the Peripheral DMA Controller avoids processor
intervention and removes the processor interrupt-handling overhead. This significantly reduces the number of
clock cycles required for a data transfer and, as a result, improves the performance of the microcontroller and
makes it more power efficient.
The PDC channels are implemented in pairs, each pair being dedicated to a particular peripheral. One channel in
the pair is dedicated to the receiving channel and one to the transmitting channel of each UART, USART, SSC and
SPI.
The user interface of a PDC channel is integrated in the memory space of each peripheral. It contains:
• two 32-bit memory pointer registers (send and receive)
• two 16-bit transfer count registers (send and receive)
• two 32-bit registers for next memory pointer (send and receive)
• two 16-bit registers for next transfer count (send and receive)
The peripheral triggers PDC transfers using transmit and receive signals. When the programmed data is trans-
ferred, an end of transfer interrupt is generated by the corresponding peripheral.
22.2 Block Diagram
Figure 22-1. Block Diagram
Control
PDC Channel 0
PDC Channel 1
THR
RHR
Control Status & Control
Peripheral Peripheral DMA Controller
Memory
Controller
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22.3 Functional Description
22.3.1 Configuration
The PDC channels user interface enables the user to configure and control the data transfers for each channel.
The user interface of a PDC channel is integrated into the user interface of the peripheral (offset 0x100), which it is
related to.
Per peripheral, it contains four 32-bit Pointer Registers (RPR, RNPR, TPR, and TNPR) and four 16-bit Counter
Registers (RCR, RNCR, TCR, and TNCR).
The size of the buffer (number of transfers) is configured in an internal 16-bit transfer counter register, and it is pos-
sible, at any moment, to read the number of transfers left for each channel.
The memory base address is configured in a 32-bit memory pointer by defining the location of the first address to
access in the memory. It is possible, at any moment, to read the location in memory of the next transfer and the
number of remaining transfers. The PDC has dedicated status registers which indicate if the transfer is enabled or
disabled for each channel. The status for each channel is located in the peripheral status register. Transfers can be
enabled and/or disabled by setting TXTEN/TXTDIS and RXTEN/RXTDIS in PDC Transfer Control Register. These
control bits enable reading the pointer and counter registers safely without any risk of their changing between both
reads.
The PDC sends status flags to the peripheral visible in its status-register (ENDRX, ENDTX, RXBUFF, and
TXBUFE).
ENDRX flag is set when the PERIPH_RCR register reaches zero.
RXBUFF flag is set when both PERIPH_RCR and PERIPH_RNCR reach zero.
ENDTX flag is set when the PERIPH_TCR register reaches zero.
TXBUFE flag is set when both PERIPH_TCR and PERIPH_TNCR reach zero.
These status flags are described in the peripheral status register.
22.3.2 Memory Pointers
Each peripheral is connected to the PDC by a receiver data channel and a transmitter data channel. Each channel
has an internal 32-bit memory pointer. Each memory pointer points to a location anywhere in the memory space
(on-chip memory or external bus interface memory).
Depending on the type of transfer (byte, half-word or word), the memory pointer is incremented by 1, 2 or 4,
respectively for peripheral transfers.
If a memory pointer is reprogrammed while the PDC is in operation, the transfer address is changed, and the PDC
performs transfers using the new address.
22.3.3 Transfer Counters
There is one internal 16-bit transfer counter for each channel used to count the size of the block already transferred
by its associated channel. These counters are decremented after each data transfer. When the counter reaches
zero, the transfer is complete and the PDC stops transferring data.
If the Next Counter Register is equal to zero, the PDC disables the trigger while activating the related peripheral
end flag.
If the counter is reprogrammed while the PDC is operating, the number of transfers is updated and the PDC counts
transfers from the new value.
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Programming the Next Counter/Pointer registers chains the buffers. The counters are decremented after each data
transfer as stated above, but when the transfer counter reaches zero, the values of the Next Counter/Pointer are
loaded into the Counter/Pointer registers in order to re-enable the triggers.
For each channel, two status bits indicate the end of the current buffer (ENDRX, ENDTX) and the end of both cur-
rent and next buffer (RXBUFF, TXBUFE). These bits are directly mapped to the peripheral status register and can
trigger an interrupt request to the AIC.
The peripheral end flag is automatically cleared when one of the counter-registers (Counter or Next Counter Reg-
ister) is written.
Note: When the Next Counter Register is loaded into the Counter Register, it is set to zero.
22.3.4 Data Transfers
The peripheral triggers PDC transfers using transmit (TXRDY) and receive (RXRDY) signals.
When the peripheral receives an external character, it sends a Receive Ready signal to the PDC which then
requests access to the system bus. When access is granted, the PDC starts a read of the peripheral Receive Hold-
ing Register (RHR) and then triggers a write in the memory.
After each transfer, the relevant PDC memory pointer is incremented and the number of transfers left is decre-
mented. When the memory block size is reached, a signal is sent to the peripheral and the transfer stops.
The same procedure is followed, in reverse, for transmit transfers.
22.3.5 Priority of PDC Transfer Requests
The Peripheral DMA Controller handles transfer requests from the channel according to priorities fixed for each
product.These priorities are defined in the product datasheet.
If simultaneous requests of the same type (receiver or transmitter) occur on identical peripherals, the priority is
determined by the numbering of the peripherals.
If transfer requests are not simultaneous, they are treated in the order they occurred. Requests from the receivers
are handled first and then followed by transmitter requests.
22.4 Peripheral DMA Controller (PDC) User Interface
Note: 1. PERIPH: Ten registers are mapped in the peripheral memory space at the same offset. These can be defined by the user
according to the function and the peripheral desired (DBGU, USART, SSC, SPI, MCI etc).
Table 22-1. Register Mapping
Offset Register Register Name Access Reset
0x100 Receive Pointer Register PERIPH(1)_RPR Read-write 0x0
0x104 Receive Counter Register PERIPH_RCR Read-write 0x0
0x108 Transmit Pointer Register PERIPH_TPR Read-write 0x0
0x10C Transmit Counter Register PERIPH_TCR Read-write 0x0
0x110 Receive Next Pointer Register PERIPH_RNPR Read-write 0x0
0x114 Receive Next Counter Register PERIPH_RNCR Read-write 0x0
0x118 Transmit Next Pointer Register PERIPH_TNPR Read-write 0x0
0x11C Transmit Next Counter Register PERIPH_TNCR Read-write 0x0
0x120 PDC Transfer Control Register PERIPH_PTCR Write-only -
0x124 PDC Transfer Status Register PERIPH_PTSR Read-only 0x0
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22.4.1 PDC Receive Pointer Register
Register Name: PERIPH_RPR
Access Type: Read-write
• RXPTR: Receive Pointer Address
Address of the next receive transfer.
22.4.2 PDC Receive Counter Register
Register Name: PERIPH_RCR
Access Type: Read-write
• RXCTR: Receive Counter Value
Number of receive transfers to be performed.
31 30 29 28 27 26 25 24
RXPTR
23 22 21 20 19 18 17 16
RXPTR
15 14 13 12 11 10 9 8
RXPTR
76543210
RXPTR
31 30 29 28 27 26 25 24
--
23 22 21 20 19 18 17 16
--
15 14 13 12 11 10 9 8
RXCTR
76543210
RXCTR
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22.4.3 PDC Transmit Pointer Register
Register Name: PERIPH_TPR
Access Type: Read-write
• TXPTR: Transmit Pointer Address
Address of the transmit buffer.
22.4.4 PDC Transmit Counter Register
Register Name: PERIPH_TCR
Access Type: Read-write
• TXCTR: Transmit Counter Value
TXCTR is the size of the transmit transfer to be performed. At zero, the peripheral data transfer is stopped.
31 30 29 28 27 26 25 24
TXPTR
23 22 21 20 19 18 17 16
TXPTR
15 14 13 12 11 10 9 8
TXPTR
76543210
TXPTR
31 30 29 28 27 26 25 24
--
23 22 21 20 19 18 17 16
--
15 14 13 12 11 10 9 8
TXCTR
76543210
TXCTR
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22.4.5 PDC Receive Next Pointer Register
Register Name: PERIPH_RNPR
Access Type: Read-write
• RXNPTR: Receive Next Pointer Address
RXNPTR is the address of the next buffer to fill with received data when the current buffer is full.
22.4.6 PDC Receive Next Counter Register
Register Name: PERIPH_RNCR
Access Type: Read-write
• RXNCR: Receive Next Counter Value
RXNCR is the size of the next buffer to receive.
31 30 29 28 27 26 25 24
RXNPTR
23 22 21 20 19 18 17 16
RXNPTR
15 14 13 12 11 10 9 8
RXNPTR
76543210
RXNPTR
31 30 29 28 27 26 25 24
--
23 22 21 20 19 18 17 16
--
15 14 13 12 11 10 9 8
RXNCR
76543210
RXNCR
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22.4.7 PDC Transmit Next Pointer Register
Register Name: PERIPH_TNPR
Access Type: Read-write
• TXNPTR: Transmit Next Pointer Address
TXNPTR is the address of the next buffer to transmit when the current buffer is empty.
22.4.8 PDC Transmit Next Counter Register
Register Name: PERIPH_TNCR
Access Type: Read-write
• TXNCR: Transmit Next Counter Value
TXNCR is the size of the next buffer to transmit.
31 30 29 28 27 26 25 24
TXNPTR
23 22 21 20 19 18 17 16
TXNPTR
15 14 13 12 11 10 9 8
TXNPTR
76543210
TXNPTR
31 30 29 28 27 26 25 24
--
23 22 21 20 19 18 17 16
--
15 14 13 12 11 10 9 8
TXNCR
76543210
TXNCR
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22.4.9 PDC Transfer Control Register
Register Name: PERIPH_PTCR
Access Type: Write-only
• RXTEN: Receiver Transfer Enable
0 = No effect.
1 = Enables the receiver PDC transfer requests if RXTDIS is not set.
• RXTDIS: Receiver Transfer Disable
0 = No effect.
1 = Disables the receiver PDC transfer requests.
• TXTEN: Transmitter Transfer Enable
0 = No effect.
1 = Enables the transmitter PDC transfer requests.
• TXTDIS: Transmitter Transfer Disable
0 = No effect.
1 = Disables the transmitter PDC transfer requests
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––TXTDISTXTEN
76543210
––––––RXTDISRXTEN
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22.4.10 PDC Transfer Status Register
Register Name: PERIPH_PTSR
Access Type: Read-only
• RXTEN: Receiver Transfer Enable
0 = Receiver PDC transfer requests are disabled.
1 = Receiver PDC transfer requests are enabled.
• TXTEN: Transmitter Transfer Enable
0 = Transmitter PDC transfer requests are disabled.
1 = Transmitter PDC transfer requests are enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––TXTEN
76543210
–––––––RXTEN
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23. Advanced Interrupt Controller (AIC)
23.1 Overview
The Advanced Interrupt Controller (AIC) is an 8-level priority, individually maskable, vectored interrupt controller,
providing handling of up to thirty-two interrupt sources. It is designed to substantially reduce the software and real-
time overhead in handling internal and external interrupts.
The AIC drives the nFIQ (fast interrupt request) and the nIRQ (standard interrupt request) inputs of an ARM pro-
cessor. Inputs of the AIC are either internal peripheral interrupts or external interrupts coming from the product's
pins.
The 8-level Priority Controller allows the user to define the priority for each interrupt source, thus permitting higher
priority interrupts to be serviced even if a lower priority interrupt is being treated.
Internal interrupt sources can be programmed to be level sensitive or edge triggered. External interrupt sources
can be programmed to be positive-edge or negative-edge triggered or high-level or low-level sensitive.
The fast forcing feature redirects any internal or external interrupt source to provide a fast interrupt rather than a
normal interrupt.
23.2 Block Diagram
Figure 23-1. Block Diagram
AIC
APB
ARM
Processor
FIQ
IRQ0-IRQn
Embedded
PeripheralEE
Peripheral
Embedded
Peripheral
Embedded
Up to
Thirty-two
Sources
nFIQ
nIRQ
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23.3 Application Block Diagram
Figure 23-2. Description of the Application Block
23.4 AIC Detailed Block Diagram
Figure 23-3. AIC Detailed Block Diagram
23.5 I/O Line Description
Advanced Interrupt Controller
Embedded Peripherals External Peripherals
(External Interrupts)
Standalone
Applications RTOS Drivers
Hard Real Time Tasks
OS-based Applications
OS Drivers
General OS Interrupt Handler
FIQ
PIO
Controller
Advanced Interrupt Controller
IRQ0-IRQn
PIOIRQ
Embedded
Peripherals
External
Source
Input
Stage
Internal
Source
Input
Stage
Fast
Forcing
Interrupt
Priority
Controller
Fast
Interrupt
Controller
ARM
Processor
nFIQ
nIRQ
Power
Management
Controller
Wake Up
User Interface
APB
Processor
Clock
Table 23-1. I/O Line Description
Pin Name Pin Description Type
FIQ Fast Interrupt Input
IRQ0 - IRQn Interrupt 0 - Interrupt n Input
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23.6 Product Dependencies
23.6.1 I/O Lines
The interrupt signals FIQ and IRQ0 to IRQn are normally multiplexed through the PIO controllers. Depending on
the features of the PIO controller used in the product, the pins must be programmed in accordance with their
assigned interrupt function. This is not applicable when the PIO controller used in the product is transparent on the
input path.
23.6.2 Power Management
The Advanced Interrupt Controller is continuously clocked. The Power Management Controller has no effect on the
Advanced Interrupt Controller behavior.
The assertion of the Advanced Interrupt Controller outputs, either nIRQ or nFIQ, wakes up the ARM processor
while it is in Idle Mode. The General Interrupt Mask feature enables the AIC to wake up the processor without
asserting the interrupt line of the processor, thus providing synchronization of the processor on an event.
23.6.3 Interrupt Sources
The Interrupt Source 0 is always located at FIQ. If the product does not feature an FIQ pin, the Interrupt Source 0
cannot be used.
The Interrupt Source 1 is always located at System Interrupt. This is the result of the OR-wiring of the system
peripheral interrupt lines, such as the System Timer, the Real Time Clock, the Power Management Controller and
the Memory Controller. When a system interrupt occurs, the service routine must first distinguish the cause of the
interrupt. This is performed by reading successively the status registers of the above mentioned system
peripherals.
The interrupt sources 2 to 31 can either be connected to the interrupt outputs of an embedded user peripheral or to
external interrupt lines. The external interrupt lines can be connected directly, or through the PIO Controller.
The PIO Controllers are considered as user peripherals in the scope of interrupt handling. Accordingly, the PIO
Controller interrupt lines are connected to the Interrupt Sources 2 to 31.
The peripheral identification defined at the product level corresponds to the interrupt source number (as well as the
bit number controlling the clock of the peripheral). Consequently, to simplify the description of the functional opera-
tions and the user interface, the interrupt sources are named FIQ, SYS, and PID2 to PID31.
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23.7 Functional Description
23.7.1 Interrupt Source Control
23.7.1.1 Interrupt Source Mode
The Advanced Interrupt Controller independently programs each interrupt source. The SRCTYPE field of the corre-
sponding AIC_SMR (Source Mode Register) selects the interrupt condition of each source.
The internal interrupt sources wired on the interrupt outputs of the embedded peripherals can be programmed
either in level-sensitive mode or in edge-triggered mode. The active level of the internal interrupts is not important
for the user.
The external interrupt sources can be programmed either in high level-sensitive or low level-sensitive modes, or in
positive edge-triggered or negative edge-triggered modes.
23.7.1.2 Interrupt Source Enabling
Each interrupt source, including the FIQ in source 0, can be enabled or disabled by using the command registers;
AIC_IECR (Interrupt Enable Command Register) and AIC_IDCR (Interrupt Disable Command Register). This set
of registers conducts enabling or disabling in one instruction. The interrupt mask can be read in the AIC_IMR reg-
ister. A disabled interrupt does not affect servicing of other interrupts.
23.7.1.3 Interrupt Clearing and Setting
All interrupt sources programmed to be edge-triggered (including the FIQ in source 0) can be individually set or
cleared by writing respectively the AIC_ISCR and AIC_ICCR registers. Clearing or setting interrupt sources pro-
grammed in level-sensitive mode has no effect.
The clear operation is perfunctory, as the software must perform an action to reinitialize the “memorization” cir-
cuitry activated when the source is programmed in edge-triggered mode. However, the set operation is available
for auto-test or software debug purposes. It can also be used to execute an AIC-implementation of a software
interrupt.
The AIC features an automatic clear of the current interrupt when the AIC_IVR (Interrupt Vector Register) is read.
Only the interrupt source being detected by the AIC as the current interrupt is affected by this operation. (See “Pri-
ority Controller” on page 167.) The automatic clear reduces the operations required by the interrupt service routine
entry code to reading the AIC_IVR. Note that the automatic interrupt clear is disabled if the interrupt source has the
Fast Forcing feature enabled as it is considered uniquely as a FIQ source. (For further details, See “Fast Forcing”
on page 171.)
The automatic clear of the interrupt source 0 is performed when AIC_FVR is read.
23.7.1.4 Interrupt Status
For each interrupt, the AIC operation originates in AIC_IPR (Interrupt Pending Register) and its mask in AIC_IMR
(Interrupt Mask Register). AIC_IPR enables the actual activity of the sources, whether masked or not.
The AIC_ISR register reads the number of the current interrupt (see “Priority Controller” on page 167) and the reg-
ister AIC_CISR gives an image of the signals nIRQ and nFIQ driven on the processor.
Each status referred to above can be used to optimize the interrupt handling of the systems.
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23.7.1.5 Internal Interrupt Source Input Stage
Figure 23-4. Internal Interrupt Source Input Stage
23.7.1.6 External Interrupt Source Input Stage
Figure 23-5. External Interrupt Source Input Stage
Edge
Detector
ClearSet
Source i AIC_IPR
AIC_IMR
AIC_IECR
AIC_IDCR
AIC_ISCR
AIC_ICCR
Fast Interrupt Controller
or
Priority Controller
FF
Level/
Edge
AIC_SMRI
(SRCTYPE)
Edge
Detector
ClearSet
Pos./Neg.
AIC_ISCR
AIC_ICCR
Source i
FF
Level/
Edge
High/Low
AIC_SMRi
SRCTYPE
AIC_IPR
AIC_IMR
AIC_IECR
AIC_IDCR
Fast Interrupt Controller
or
Priority Controller
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23.7.2 Interrupt Latencies
Global interrupt latencies depend on several parameters, including:
• The time the software masks the interrupts.
• Occurrence, either at the processor level or at the AIC level.
• The execution time of the instruction in progress when the interrupt occurs.
• The treatment of higher priority interrupts and the resynchronization of the hardware signals.
This section addresses only the hardware resynchronizations. It gives details of the latency times between the
event on an external interrupt leading in a valid interrupt (edge or level) or the assertion of an internal interrupt
source and the assertion of the nIRQ or nFIQ line on the processor. The resynchronization time depends on the
programming of the interrupt source and on its type (internal or external). For the standard interrupt, resynchroniza-
tion times are given assuming there is no higher priority in progress.
The PIO Controller multiplexing has no effect on the interrupt latencies of the external interrupt sources.
23.7.2.1 External Interrupt Edge Triggered Source
Figure 23-6. External Interrupt Edge Triggered Source
23.7.2.2 External Interrupt Level Sensitive Source
Figure 23-7. External Interrupt Level Sensitive Source
Maximum FIQ Latency = 4 Cycles
Maximum IRQ Latency = 4 Cycles
nFIQ
nIRQ
MCK
IRQ or FIQ
(Positive Edge)
IRQ or FIQ
(Negative Edge)
Maximum IRQ
Latency = 3 Cycles
Maximum FIQ
Latency = 3 cycles
MCK
IRQ or FIQ
(High Level)
IRQ or FIQ
(Low Level)
nIRQ
nFIQ
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23.7.2.3 Internal Interrupt Edge Triggered Source
Figure 23-8. Internal Interrupt Edge Triggered Source
23.7.2.4 Internal Interrupt Level Sensitive Source
Figure 23-9. Internal Interrupt Level Sensitive Source
23.7.3 Normal Interrupt
23.7.3.1 Priority Controller
An 8-level priority controller drives the nIRQ line of the processor, depending on the interrupt conditions occurring
on the interrupt sources 1 to 31 (except for those programmed in Fast Forcing).
Each interrupt source has a programmable priority level of 7 to 0, which is user-definable by writing the PRIOR field
of the corresponding AIC_SMR (Source Mode Register). Level 7 is the highest priority and level 0 the lowest.
As soon as an interrupt condition occurs, as defined by the SRCTYPE field of the AIC_SMR (Source Mode Regis-
ter), the nIRQ line is asserted. As a new interrupt condition might have happened on other interrupt sources since
the nIRQ has been asserted, the priority controller determines the current interrupt at the time the AIC_IVR (Inter-
rupt Vector Register) is read. The read of AIC_IVR is the entry point of the interrupt handling which allows the
AIC to consider that the interrupt has been taken into account by the software.
The current priority level is defined as the priority level of the current interrupt.
If several interrupt sources of equal priority are pending and enabled when the AIC_IVR is read, the interrupt with
the lowest interrupt source number is serviced first.
The nIRQ line can be asserted only if an interrupt condition occurs on an interrupt source with a higher priority. If
an interrupt condition happens (or is pending) during the interrupt treatment in progress, it is delayed until the soft-
ware indicates to the AIC the end of the current service by writing the AIC_EOICR (End of Interrupt Command
Register). The write of AIC_EOICR is the exit point of the interrupt handling.
MCK
nIRQ
Peripheral Interrupt
Becomes Active
Maximum IRQ Latency = 4.5 Cycles
MCK
nIRQ
Maximum IRQ Latency = 3.5 Cycles
Peripheral Interrupt
Becomes Active
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23.7.3.2 Interrupt Nesting
The priority controller utilizes interrupt nesting in order for the high priority interrupt to be handled during the service
of lower priority interrupts. This requires the interrupt service routines of the lower interrupts to re-enable the inter-
rupt at the processor level.
When an interrupt of a higher priority happens during an already occurring interrupt service routine, the nIRQ line is
re-asserted. If the interrupt is enabled at the core level, the current execution is interrupted and the new interrupt
service routine should read the AIC_IVR. At this time, the current interrupt number and its priority level are pushed
into an embedded hardware stack, so that they are saved and restored when the higher priority interrupt servicing
is finished and the AIC_EOICR is written.
The AIC is equipped with an 8-level wide hardware stack in order to support up to eight interrupt nestings pursuant
to having eight priority levels.
23.7.3.3 Interrupt Vectoring
The interrupt handler addresses corresponding to each interrupt source can be stored in the registers AIC_SVR1
to AIC_SVR31 (Source Vector Register 1 to 31). When the processor reads AIC_IVR (Interrupt Vector Register),
the value written into AIC_SVR corresponding to the current interrupt is returned.
This feature offers a way to branch in one single instruction to the handler corresponding to the current interrupt, as
AIC_IVR is mapped at the absolute address 0xFFFF F100 and thus accessible from the ARM interrupt vector at
address 0x0000 0018 through the following instruction:
LDR PC,[PC,# -&F20]
When the processor executes this instruction, it loads the read value in AIC_IVR in its program counter, thus
branching the execution on the correct interrupt handler.
This feature is often not used when the application is based on an operating system (either real time or not). Oper-
ating systems often have a single entry point for all the interrupts and the first task performed is to discern the
source of the interrupt.
However, it is strongly recommended to port the operating system on AT91 products by supporting the interrupt
vectoring. This can be performed by defining all the AIC_SVR of the interrupt source to be handled by the operat-
ing system at the address of its interrupt handler. When doing so, the interrupt vectoring permits a critical interrupt
to transfer the execution on a specific very fast handler and not onto the operating system’s general interrupt han-
dler. This facilitates the support of hard real-time tasks (input/outputs of voice/audio buffers and software
peripheral handling) to be handled efficiently and independently of the application running under an operating
system.
23.7.3.4 Interrupt Handlers
This section gives an overview of the fast interrupt handling sequence when using the AIC. It is assumed that the
programmer understands the architecture of the ARM processor, and especially the processor interrupt modes and
the associated status bits.
It is assumed that:
1. The Advanced Interrupt Controller has been programmed, AIC_SVR registers are loaded with corre-
sponding interrupt service routine addresses and interrupts are enabled.
2. The instruction at the ARM interrupt exception vector address is required to work with the vectoring
LDR PC, [PC, # -&F20]
When nIRQ is asserted, if the bit “I” of CPSR is 0, the sequence is as follows:
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1. The CPSR is stored in SPSR_irq, the current value of the Program Counter is loaded in the Interrupt link
register (R14_irq) and the Program Counter (R15) is loaded with 0x18. In the following cycle during fetch
at address 0x1C, the ARM core adjusts R14_irq, decrementing it by four.
2. The ARM core enters Interrupt mode, if it has not already done so.
3. When the instruction loaded at address 0x18 is executed, the program counter is loaded with the value
read in AIC_IVR. Reading the AIC_IVR has the following effects:
– Sets the current interrupt to be the pending and enabled interrupt with the highest priority. The current
level is the priority level of the current interrupt.
– De-asserts the nIRQ line on the processor. Even if vectoring is not used, AIC_IVR must be read in
order to de-assert nIRQ.
– Automatically clears the interrupt, if it has been programmed to be edge-triggered.
– Pushes the current level and the current interrupt number on to the stack.
– Returns the value written in the AIC_SVR corresponding to the current interrupt.
4. The previous step has the effect of branching to the corresponding interrupt service routine. This should
start by saving the link register (R14_irq) and SPSR_IRQ. The link register must be decremented by four
when it is saved if it is to be restored directly into the program counter at the end of the interrupt. For
example, the instruction SUB PC, LR, #4 may be used.
5. Further interrupts can then be unmasked by clearing the “I” bit in CPSR, allowing re-assertion of the nIRQ
to be taken into account by the core. This can happen if an interrupt with a higher priority than the current
interrupt occurs.
6. The interrupt handler can then proceed as required, saving the registers that will be used and restoring
them at the end. During this phase, an interrupt of higher priority than the current level will restart the
sequence from step 1.
Note: If the interrupt is programmed to be level sensitive, the source of the interrupt must be cleared during this phase.
7. The “I” bit in CPSR must be set in order to mask interrupts before exiting to ensure that the interrupt is
completed in an orderly manner.
8. The End of Interrupt Command Register (AIC_EOICR) must be written in order to indicate to the AIC that
the current interrupt is finished. This causes the current level to be popped from the stack, restoring the
previous current level if one exists on the stack. If another interrupt is pending, with lower or equal priority
than the old current level but with higher priority than the new current level, the nIRQ line is re-asserted,
but the interrupt sequence does not immediately start because the “I” bit is set in the core. SPSR_irq is
restored. Finally, the saved value of the link register is restored directly into the PC. This has the effect of
returning from the interrupt to whatever was being executed before, and of loading the CPSR with the
stored SPSR, masking or unmasking the interrupts depending on the state saved in SPSR_irq.
Note: The “I” bit in SPSR is significant. If it is set, it indicates that the ARM core was on the verge of masking an interrupt
when the mask instruction was interrupted. Hence, when SPSR is restored, the mask instruction is completed (inter-
rupt is masked).
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23.7.4 Fast Interrupt
23.7.4.1 Fast Interrupt Source
The interrupt source 0 is the only source which can raise a fast interrupt request to the processor except if fast forc-
ing is used. The interrupt source 0 is generally connected to a FIQ pin of the product, either directly or through a
PIO Controller.
23.7.4.2 Fast Interrupt Control
The fast interrupt logic of the AIC has no priority controller. The mode of interrupt source 0 is programmed with the
AIC_SMR0 and the field PRIOR of this register is not used even if it reads what has been written. The field SRC-
TYPE of AIC_SMR0 enables programming the fast interrupt source to be positive-edge triggered or negative-edge
triggered or high-level sensitive or low-level sensitive
Writing 0x1 in the AIC_IECR (Interrupt Enable Command Register) and AIC_IDCR (Interrupt Disable Command
Register) respectively enables and disables the fast interrupt. The bit 0 of AIC_IMR (Interrupt Mask Register) indi-
cates whether the fast interrupt is enabled or disabled.
23.7.4.3 Fast Interrupt Vectoring
The fast interrupt handler address can be stored in AIC_SVR0 (Source Vector Register 0). The value written into
this register is returned when the processor reads AIC_FVR (Fast Vector Register). This offers a way to branch in
one single instruction to the interrupt handler, as AIC_FVR is mapped at the absolute address 0xFFFF F104 and
thus accessible from the ARM fast interrupt vector at address 0x0000 001C through the following instruction:
LDR PC,[PC,# -&F20]
When the processor executes this instruction it loads the value read in AIC_FVR in its program counter, thus
branching the execution on the fast interrupt handler. It also automatically performs the clear of the fast interrupt
source if it is programmed in edge-triggered mode.
23.7.4.4 Fast Interrupt Handlers
This section gives an overview of the fast interrupt handling sequence when using the AIC. It is assumed that the
programmer understands the architecture of the ARM processor, and especially the processor interrupt modes and
associated status bits.
Assuming that:
1. The Advanced Interrupt Controller has been programmed, AIC_SVR0 is loaded with the fast interrupt ser-
vice routine address, and the interrupt source 0 is enabled.
2. The Instruction at address 0x1C (FIQ exception vector address) is required to vector the fast interrupt:
LDR PC, [PC, # -&F20]
3. The user does not need nested fast interrupts.
When nFIQ is asserted, if the bit “F” of CPSR is 0, the sequence is:
1. The CPSR is stored in SPSR_fiq, the current value of the program counter is loaded in the FIQ link regis-
ter (R14_FIQ) and the program counter (R15) is loaded with 0x1C. In the following cycle, during fetch at
address 0x20, the ARM core adjusts R14_fiq, decrementing it by four.
2. The ARM core enters FIQ mode.
3. When the instruction loaded at address 0x1C is executed, the program counter is loaded with the value
read in AIC_FVR. Reading the AIC_FVR has effect of automatically clearing the fast interrupt, if it has
been programmed to be edge triggered. In this case only, it de-asserts the nFIQ line on the processor.
4. The previous step enables branching to the corresponding interrupt service routine. It is not necessary to
save the link register R14_fiq and SPSR_fiq if nested fast interrupts are not needed.
5. The Interrupt Handler can then proceed as required. It is not necessary to save registers R8 to R13
because FIQ mode has its own dedicated registers and the user R8 to R13 are banked. The other regis-
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ters, R0 to R7, must be saved before being used, and restored at the end (before the next step). Note that
if the fast interrupt is programmed to be level sensitive, the source of the interrupt must be cleared during
this phase in order to de-assert the interrupt source 0.
6. Finally, the Link Register R14_fiq is restored into the PC after decrementing it by four (with instruction
SUB PC, LR, #4 for example). This has the effect of returning from the interrupt to whatever was being
executed before, loading the CPSR with the SPSR and masking or unmasking the fast interrupt depend-
ing on the state saved in the SPSR.
Note: The “F” bit in SPSR is significant. If it is set, it indicates that the ARM core was just about to mask FIQ interrupts when
the mask instruction was interrupted. Hence when the SPSR is restored, the interrupted instruction is completed (FIQ
is masked).
Another way to handle the fast interrupt is to map the interrupt service routine at the address of the ARM vector
0x1C. This method does not use the vectoring, so that reading AIC_FVR must be performed at the very beginning
of the handler operation. However, this method saves the execution of a branch instruction.
23.7.4.5 Fast Forcing
The Fast Forcing feature of the advanced interrupt controller provides redirection of any normal Interrupt source on
the fast interrupt controller.
Fast Forcing is enabled or disabled by writing to the Fast Forcing Enable Register (AIC_FFER) and the Fast Forc-
ing Disable Register (AIC_FFDR). Writing to these registers results in an update of the Fast Forcing Status
Register (AIC_FFSR) that controls the feature for each internal or external interrupt source.
When Fast Forcing is disabled, the interrupt sources are handled as described in the previous pages.
When Fast Forcing is enabled, the edge/level programming and, in certain cases, edge detection of the interrupt
source is still active but the source cannot trigger a normal interrupt to the processor and is not seen by the priority
handler.
If the interrupt source is programmed in level-sensitive mode and an active level is sampled, Fast Forcing results in
the assertion of the nFIQ line to the core.
If the interrupt source is programmed in edge-triggered mode and an active edge is detected, Fast Forcing results
in the assertion of the nFIQ line to the core.
The Fast Forcing feature does not affect the Source 0 pending bit in the Interrupt Pending Register (AIC_IPR).
The FIQ Vector Register (AIC_FVR) reads the contents of the Source Vector Register 0 (AIC_SVR0), whatever the
source of the fast interrupt may be. The read of the FVR does not clear the Source 0 when the fast forcing feature
is used and the interrupt source should be cleared by writing to the Interrupt Clear Command Register
(AIC_ICCR).
All enabled and pending interrupt sources that have the fast forcing feature enabled and that are programmed in
edge-triggered mode must be cleared by writing to the Interrupt Clear Command Register. In doing so, they are
cleared independently and thus lost interrupts are prevented.
The read of AIC_IVR does not clear the source that has the fast forcing feature enabled.
The source 0, reserved to the fast interrupt, continues operating normally and becomes one of the Fast Interrupt
sources.
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Figure 23-10. Fast Forcing
Source 0 _ FIQ
Input Stage
Automatic Clear
Input Stage
Automatic Clear
Source n
AIC_IPR
AIC_IMR
AIC_FFSR
AIC_IPR
AIC_IMR
Priority
Manager
nFIQ
nIRQ
Read IVR if Source n is the current interrupt
and if Fast Forcing is disabled on Source n.
Read FVR if Fast Forcing is
disabled on Sources 1 to 31.
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23.7.5 Protect Mode
The Protect Mode permits reading the Interrupt Vector Register without performing the associated automatic oper-
ations. This is necessary when working with a debug system. When a debugger, working either with a Debug
Monitor or the ARM processor's ICE, stops the applications and updates the opened windows, it might read the
AIC User Interface and thus the IVR. This has undesirable consequences:
• If an enabled interrupt with a higher priority than the current one is pending, it is stacked.
• If there is no enabled pending interrupt, the spurious vector is returned.
In either case, an End of Interrupt command is necessary to acknowledge and to restore the context of the AIC.
This operation is generally not performed by the debug system as the debug system would become strongly intru-
sive and cause the application to enter an undesired state.
This is avoided by using the Protect Mode. Writing DBGM in AIC_DCR (Debug Control Register) at 0x1 enables
the Protect Mode.
When the Protect Mode is enabled, the AIC performs interrupt stacking only when a write access is performed on
the AIC_IVR. Therefore, the Interrupt Service Routines must write (arbitrary data) to the AIC_IVR just after reading
it. The new context of the AIC, including the value of the Interrupt Status Register (AIC_ISR), is updated with the
current interrupt only when AIC_IVR is written.
An AIC_IVR read on its own (e.g., by a debugger), modifies neither the AIC context nor the AIC_ISR. Extra
AIC_IVR reads perform the same operations. However, it is recommended to not stop the processor between the
read and the write of AIC_IVR of the interrupt service routine to make sure the debugger does not modify the AIC
context.
To summarize, in normal operating mode, the read of AIC_IVR performs the following operations within the AIC:
1. Calculates active interrupt (higher than current or spurious).
2. Determines and returns the vector of the active interrupt.
3. Memorizes the interrupt.
4. Pushes the current priority level onto the internal stack.
5. Acknowledges the interrupt.
However, while the Protect Mode is activated, only operations 1 to 3 are performed when AIC_IVR is read. Opera-
tions 4 and 5 are only performed by the AIC when AIC_IVR is written.
Software that has been written and debugged using the Protect Mode runs correctly in Normal Mode without mod-
ification. However, in Normal Mode the AIC_IVR write has no effect and can be removed to optimize the code.
23.7.6 Spurious Interrupt
The Advanced Interrupt Controller features protection against spurious interrupts. A spurious interrupt is defined as
being the assertion of an interrupt source long enough for the AIC to assert the nIRQ, but no longer present when
AIC_IVR is read. This is most prone to occur when:
• An external interrupt source is programmed in level-sensitive mode and an active level occurs for only a short
time.
• An internal interrupt source is programmed in level sensitive and the output signal of the corresponding
embedded peripheral is activated for a short time. (As in the case for the Watchdog.)
• An interrupt occurs just a few cycles before the software begins to mask it, thus resulting in a pulse on the
interrupt source.
The AIC detects a spurious interrupt at the time the AIC_IVR is read while no enabled interrupt source is pending.
When this happens, the AIC returns the value stored by the programmer in AIC_SPU (Spurious Vector Register).
The programmer must store the address of a spurious interrupt handler in AIC_SPU as part of the application, to
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enable an as fast as possible return to the normal execution flow. This handler writes in AIC_EOICR and performs
a return from interrupt.
23.7.7 General Interrupt Mask
The AIC features a General Interrupt Mask bit to prevent interrupts from reaching the processor. Both the nIRQ
and the nFIQ lines are driven to their inactive state if the bit GMSK in AIC_DCR (Debug Control Register) is set.
However, this mask does not prevent waking up the processor if it has entered Idle Mode. This function facilitates
synchronizing the processor on a next event and, as soon as the event occurs, performs subsequent operations
without having to handle an interrupt. It is strongly recommended to use this mask with caution.
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23.8 Advanced Interrupt Controller (AIC) User Interface
23.8.1 Base Address
The AIC is mapped at the address 0xFFFF F000. It has a total 4-Kbyte addressing space. This permits the vectoring fea-
ture, as the PC-relative load/store instructions of the ARM processor support only an ± 4-Kbyte offset.
Notes: 1. The reset value of this register depends on the level of the external interrupt source. All other sources are cleared at reset,
thus not pending.
2. PID2...PID31 bit fields refer to the identifiers as defined in the Peripheral Identifiers Section of the product datasheet.
23.8.2 AIC Source Mode Register
Register Name: AIC_SMR0..AIC_SMR31
Table 23-2. Register Mapping
Offset Register Name Access Reset
0000 Source Mode Register 0 AIC_SMR0 Read/Write 0x0
0x04 Source Mode Register 1 AIC_SMR1 Read/Write 0x0
--- --- --- --- ---
0x7C Source Mode Register 31 AIC_SMR31 Read/Write 0x0
0x80 Source Vector Register 0 AIC_SVR0 Read/Write 0x0
0x84 Source Vector Register 1 AIC_SVR1 Read/Write 0x0
--- --- --- --- ---
0xFC Source Vector Register 31 AIC_SVR31 Read/Write 0x0
0x100 Interrupt Vector Register AIC_IVR Read-only 0x0
0x104 FIQ Interrupt Vector Register AIC_FVR Read-only 0x0
0x108 Interrupt Status Register AIC_ISR Read-only 0x0
0x10C Interrupt Pending Register(2) AIC_IPR Read-only 0x0(1)
0x110 Interrupt Mask Register(2) AIC_IMR Read-only 0x0
0x114 Core Interrupt Status Register AIC_CISR Read-only 0x0
0x118 Reserved --- --- ---
0x11C Reserved --- --- ---
0x120 Interrupt Enable Command Register(2) AIC_IECR Write-only ---
0x124 Interrupt Disable Command Register(2) AIC_IDCR Write-only ---
0x128 Interrupt Clear Command Register(2) AIC_ICCR Write-only ---
0x12C Interrupt Set Command Register(2) AIC_ISCR Write-only ---
0x130 End of Interrupt Command Register AIC_EOICR Write-only ---
0x134 Spurious Interrupt Vector Register AIC_SPU Read/Write 0x0
0x138 Debug Control Register AIC_DCR Read/Write 0x0
0x13C Reserved --- --- ---
0x140 Fast Forcing Enable Register(2) AIC_FFER Write-only ---
0x144 Fast Forcing Disable Register(2) AIC_FFDR Write-only ---
0x148 Fast Forcing Status Register(2) AIC_FFSR Read-only 0x0
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Access Type: Read/Write
Reset Value: 0x0
• PRIOR: Priority Level
Programs the priority level for all sources except FIQ source (source 0).
The priority level can be between 0 (lowest) and 7 (highest).
The priority level is not used for the FIQ in the related SMR register AIC_SMRx.
• SRCTYPE: Interrupt Source Type
The active level or edge is not programmable for the internal interrupt sources.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
– SRCTYPE – – PRIOR
SRCTYPE Internal Interrupt Sources External Interrupt Sources
0 0 High level Sensitive Low level Sensitive
0 1 Positive edge triggered Negative edge triggered
1 0 High level Sensitive High level Sensitive
1 1 Positive edge triggered Positive edge triggered
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23.8.3 AIC Source Vector Register
Register Name: AIC_SVR0..AIC_SVR31
Access Type: Read/Write
Reset Value: 0x0
• VECTOR: Source Vector
The user may store in these registers the addresses of the corresponding handler for each interrupt source.
23.8.4 AIC Interrupt Vector Register
Register Name: AIC_IVR
Access Type: Read-only
Reset Value: 0x0
• IRQV: Interrupt Vector Register
The Interrupt Vector Register contains the vector programmed by the user in the Source Vector Register corresponding to
the current interrupt.
The Source Vector Register is indexed using the current interrupt number when the Interrupt Vector Register is read.
When there is no current interrupt, the Interrupt Vector Register reads the value stored in AIC_SPU.
31 30 29 28 27 26 25 24
VECTOR
23 22 21 20 19 18 17 16
VECTOR
15 14 13 12 11 10 9 8
VECTOR
76543210
VECTOR
31 30 29 28 27 26 25 24
IRQV
23 22 21 20 19 18 17 16
IRQV
15 14 13 12 11 10 9 8
IRQV
76543210
IRQV
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23.8.5 AIC FIQ Vector Register
Register Name: AIC_FVR
Access Type: Read-only
Reset Value: 0 x0
• FIQV: FIQ Vector Register
The FIQ Vector Register contains the vector programmed by the user in the Source Vector Register 0. When there is no
fast interrupt, the FIQ Vector Register reads the value stored in AIC_SPU.
23.8.6 AIC Interrupt Status Register
Register Name: AIC_ISR
Access Type: Read-only
Reset Value: 0x0
• IRQID: Current Interrupt Identifier
The Interrupt Status Register returns the current interrupt source number.
31 30 29 28 27 26 25 24
FIQV
23 22 21 20 19 18 17 16
FIQV
15 14 13 12 11 10 9 8
FIQV
76543210
FIQV
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––– IRQID
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23.8.7 AIC Interrupt Pending Register
Register Name: AIC_IPR
Access Type: Read-only
Reset Value: 0x0
• FIQ, SYS, PID2-PID31: Interrupt Pending
0 = Corresponding interrupt is not pending.
1 = Corresponding interrupt is pending.
23.8.8 AIC Interrupt Mask Register
Register Name: AIC_IMR
Access Type: Read-only
Reset Value: 0x0
• FIQ, SYS, PID2-PID31: Interrupt Mask
0 = Corresponding interrupt is disabled.
1 = Corresponding interrupt is enabled.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
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23.8.9 AIC Core Interrupt Status Register
Register Name: AIC_CISR
Access Type: Read-only
Reset Value: 0x0
• NFIQ: NFIQ Status
0 = nFIQ line is deactivated.
1 = nFIQ line is active.
• NIRQ: NIRQ Status
0 = nIRQ line is deactivated.
1 = nIRQ line is active.
23.8.10 AIC Interrupt Enable Command Register
Register Name: AIC_IECR
Access Type: Write-only
• FIQ, SYS, PID2-PID3: Interrupt Enable
0 = No effect.
1 = Enables corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––NIRQNIFQ
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
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23.8.11 AIC Interrupt Disable Command Register
Register Name: AIC_IDCR
Access Type: Write-only
• FIQ, SYS, PID2-PID31: Interrupt Disable
0 = No effect.
1 = Disables corresponding interrupt.
23.8.12 AIC Interrupt Clear Command Register
Register Name: AIC_ICCR
Access Type: Write-only
• FIQ, SYS, PID2-PID31: Interrupt Clear
0 = No effect.
1 = Clears corresponding interrupt.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
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23.8.13 AIC Interrupt Set Command Register
Register Name: AIC_ISCR
Access Type: Write-only
• FIQ, SYS, PID2-PID31: Interrupt Set
0 = No effect.
1 = Sets corresponding interrupt.
23.8.14 AIC End of Interrupt Command Register
Register Name: AIC_EOICR
Access Type: Write-only
The End of Interrupt Command Register is used by the interrupt routine to indicate that the interrupt treatment is complete.
Any value can be written because it is only necessary to make a write to this register location to signal the end of interrupt
treatment.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS FIQ
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––––
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23.8.15 AIC Spurious Interrupt Vector Register
Register Name: AIC_SPU
Access Type: Read/Write
Reset Value: 0x0
• SIVR: Spurious Interrupt Vector Register
The user may store the address of a spurious interrupt handler in this register. The written value is returned in AIC_IVR in
case of a spurious interrupt and in AIC_FVR in case of a spurious fast interrupt.
23.8.16 AIC Debug Control Register
Register Name: AIC_DEBUG
Access Type: Read/Write
Reset Value: 0x0
• PROT: Protection Mode
0 = The Protection Mode is disabled.
1 = The Protection Mode is enabled.
• GMSK: General Mask
0 = The nIRQ and nFIQ lines are normally controlled by the AIC.
1 = The nIRQ and nFIQ lines are tied to their inactive state.
31 30 29 28 27 26 25 24
SIVR
23 22 21 20 19 18 17 16
SIVR
15 14 13 12 11 10 9 8
SIVR
76543210
SIVR
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––GMSKPROT
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23.8.17 AIC Fast Forcing Enable Register
Register Name: AIC_FFER
Access Type: Write-only
• SYS, PID2-PID31: Fast Forcing Enable
0 = No effect.
1 = Enables the fast forcing feature on the corresponding interrupt.
23.8.18 AIC Fast Forcing Disable Register
Register Name: AIC_FFDR
Access Type: Write-only
• SYS, PID2-PID31: Fast Forcing Disable
0 = No effect.
1 = Disables the Fast Forcing feature on the corresponding interrupt.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS –
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS –
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23.8.19 AIC Fast Forcing Status Register
Register Name: AIC_FFSR
Access Type: Read-only
• SYS, PID2-PID31: Fast Forcing Status
0 = The Fast Forcing feature is disabled on the corresponding interrupt.
1 = The Fast Forcing feature is enabled on the corresponding interrupt.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 SYS –
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24. Clock Generator
24.1 Overview
The Clock Generator is made up of 1 PLL, a Main Oscillator, as well as an RC Oscillator.
It provides the following clocks:
• SLCK, the Slow Clock, which is the only permanent clock within the system
• MAINCK is the output of the Main Oscillator
• PLLCK is the output of the Divider and PLL block
The Clock Generator User Interface is embedded within the Power Management Controller one and is described in
Section 25.9. However, the Clock Generator registers are named CKGR_.
24.2 Slow Clock RC Oscillator
The user has to take into account the possible drifts of the RC Oscillator. More details are given in the section “DC
Characteristics” of the product datasheet.
24.3 Main Oscillator
Figure 24-1 shows the Main Oscillator block diagram.
Figure 24-1. Main Oscillator Block Diagram
24.3.1 Main Oscillator Connections
The Clock Generator integrates a Main Oscillator that is designed for a 3 to 20 MHz fundamental crystal. The typi-
cal crystal connection is illustrated in Figure 24-2. For further details on the electrical characteristics of the Main
Oscillator, see the section “DC Characteristics” of the product datasheet.
XIN
XOUT
MOSCEN
Main
Oscillator
Counter
OSCOUNT
MOSCS
MAINCK
Main Clock
Main Clock
Frequency
Counter
MAINF
MAINRDY
SLCK
Slow Clock
Main
Oscillator
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Figure 24-2. Typical Crystal Connection
24.3.2 Main Oscillator Startup Time
The startup time of the Main Oscillator is given in the DC Characteristics section of the product datasheet. The
startup time depends on the crystal frequency and decreases when the frequency rises.
24.3.3 Main Oscillator Control
To minimize the power required to start up the system, the main oscillator is disabled after reset and slow clock is
selected.
The software enables or disables the main oscillator so as to reduce power consumption by clearing the MOSCEN
bit in the Main Oscillator Register (CKGR_MOR).
When disabling the main oscillator by clearing the MOSCEN bit in CKGR_MOR, the MOSCS bit in PMC_SR is
automatically cleared, indicating the main clock is off.
When enabling the main oscillator, the user must initiate the main oscillator counter with a value corresponding to
the startup time of the oscillator. This startup time depends on the crystal frequency connected to the main
oscillator.
When the MOSCEN bit and the OSCOUNT are written in CKGR_MOR to enable the main oscillator, the MOSCS
bit in PMC_SR (Status Register) is cleared and the counter starts counting down on the slow clock divided by 8
from the OSCOUNT value. Since the OSCOUNT value is coded with 8 bits, the maximum startup time is about 62
ms.
When the counter reaches 0, the MOSCS bit is set, indicating that the main clock is valid. Setting the MOSCS bit in
PMC_IMR can trigger an interrupt to the processor.
24.3.4 Main Clock Frequency Counter
The Main Oscillator features a Main Clock frequency counter that provides the quartz frequency connected to the
Main Oscillator. Generally, this value is known by the system designer; however, it is useful for the boot program to
configure the device with the correct clock speed, independently of the application.
The Main Clock frequency counter starts incrementing at the Main Clock speed after the next rising edge of the
Slow Clock as soon as the Main Oscillator is stable, i.e., as soon as the MOSCS bit is set. Then, at the 16th falling
edge of Slow Clock, the MAINRDY bit in CKGR_MCFR (Main Clock Frequency Register) is set and the counter
stops counting. Its value can be read in the MAINF field of CKGR_MCFR and gives the number of Main Clock
cycles during 16 periods of Slow Clock, so that the frequency of the crystal connected on the Main Oscillator can
be determined.
1K
XIN XOUT GND
SAM7S Microcontroller
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24.3.5 Main Oscillator Bypass
The user can input a clock on the device instead of connecting a crystal. In this case, the user has to provide the
external clock signal on the XIN pin. The input characteristics of the XIN pin under these conditions are given in the
product electrical characteristics section. The programmer has to be sure to set the OSCBYPASS bit to 1 and the
MOSCEN bit to 0 in the Main OSC register (CKGR_MOR) for the external clock to operate properly.
24.4 Divider and PLL Block
The PLL embeds an input divider to increase the accuracy of the resulting clock signals. However, the user must
respect the PLL minimum input frequency when programming the divider.
Figure 24-3 shows the block diagram of the divider and PLL block.
Figure 24-3. Divider and PLL Block Diagram
24.4.1 PLL Filter
The PLL requires connection to an external second-order filter through the PLLRC pin. Figure 24-4 shows a sche-
matic of these filters.
Figure 24-4. PLL Capacitors and Resistors
Values of R, C1 and C2 to be connected to the PLLRC pin must be calculated as a function of the PLL input fre-
quency, the PLL output frequency and the phase margin. A trade-off has to be found between output signal
overshoot and startup time.
24.4.2 Divider and Phase Lock Loop Programming
The divider can be set between 1 and 255 in steps of 1. When a divider field (DIV) is set to 0, the output of the cor-
responding divider and the PLL output is a continuous signal at level 0. On reset, each DIV field is set to 0, thus the
corresponding PLL input clock is set to 0.
The PLL allows multiplication of the divider’s outputs. The PLL clock signal has a frequency that depends on the
respective source signal frequency and on the parameters DIV and MUL. The factor applied to the source signal
Divider
PLLRC
DIV
PLL
MUL
PLLCOUNT
LOCK
OUT
SLCK
MAINCK PLLCK
PLL
Counter
GND
C1
C2
PLL
PLLRC
R
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frequency is (MUL + 1)/DIV. When MUL is written to 0, the corresponding PLL is disabled and its power consump-
tion is saved. Re-enabling the PLL can be performed by writing a value higher than 0 in the MUL field.
Whenever the PLL is re-enabled or one of its parameters is changed, the LOCK bit in PMC_SR is automatically
cleared. The values written in the PLLCOUNT field in CKGR_PLLR are loaded in the PLL counter. The PLL coun-
ter then decrements at the speed of the Slow Clock until it reaches 0. At this time, the LOCK bit is set in PMC_SR
and can trigger an interrupt to the processor. The user has to load the number of Slow Clock cycles required to
cover the PLL transient time into the PLLCOUNT field. The transient time depends on the PLL filter. The initial
state of the PLL and its target frequency can be calculated using a specific tool provided by Atmel.
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25. Power Management Controller (PMC)
25.1 Description
The Power Management Controller (PMC) optimizes power consumption by controlling all system and user periph-
eral clocks. The PMC enables/disables the clock inputs to many of the peripherals and the ARM Processor.
The Power Management Controller provides the following clocks:
• MCK, the Master Clock, programmable from a few hundred Hz to the maximum operating frequency of the
device. It is available to the modules running permanently, such as the AIC and the Memory Controller.
• Processor Clock (PCK), switched off when entering processor in idle mode.
• Peripheral Clocks, typically MCK, provided to the embedded peripherals (USART, SSC, SPI, TWI, TC, MCI,
etc.) and independently controllable. In order to reduce the number of clock names in a product, the Peripheral
Clocks are named MCK in the product datasheet.
• UDP Clock (UDPCK), required by USB Device Port operations. (Does not pertain to SAM7S32/16.)
• Programmable Clock Outputs can be selected from the clocks provided by the clock generator and driven on
the PCKx pins.
25.2 Master Clock Controller
The Master Clock Controller provides selection and division of the Master Clock (MCK). MCK is the clock provided
to all the peripherals and the memory controller.
The Master Clock is selected from one of the clocks provided by the Clock Generator. Selecting the Slow Clock
provides a Slow Clock signal to the whole device. Selecting the Main Clock saves power consumption of the PLL.
The Master Clock Controller is made up of a clock selector and a prescaler.
The Master Clock selection is made by writing the CSS field (Clock Source Selection) in PMC_MCKR (Master
Clock Register). The prescaler supports the division by a power of 2 of the selected clock between 1 and 64. The
PRES field in PMC_MCKR programs the prescaler.
Each time PMC_MCKR is written to define a new Master Clock, the MCKRDY bit is cleared in PMC_SR. It reads 0
until the Master Clock is established. Then, the MCKRDY bit is set and can trigger an interrupt to the processor.
This feature is useful when switching from a high-speed clock to a lower one to inform the software when the
change is actually done.
Figure 25-1. Master Clock Controller
25.3 Processor Clock Controller
The PMC features a Processor Clock Controller (PCK) that implements the Processor Idle Mode. The Processor
Clock can be disabled by writing the System Clock Disable Register (PMC_SCDR). The status of this clock (at
least for debug purpose) can be read in the System Clock Status Register (PMC_SCSR).
SLCK
Master Clock
Prescaler MCK
PRESCSS
MAINCK
PLLCK
To the Processor
Clock Controller (PCK)
PMC_MCKR PMC_MCKR
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The Processor Clock PCK is enabled after a reset and is automatically re-enabled by any enabled interrupt. The
Processor Idle Mode is achieved by disabling the Processor Clock, which is automatically re-enabled by any
enabled fast or normal interrupt, or by the reset of the product.
When the Processor Clock is disabled, the current instruction is finished before the clock is stopped, but this does
not prevent data transfers from other masters of the system bus.
25.4 USB Clock Controller
Note: The USB Clock Controller does not pertain to SAM7S32/16.
The USB Source Clock is the PLL output. If using the USB, the user must program the PLL to generate a 48 MHz,
a 96 MHz or a 192 MHz signal with an accuracy of ± 0.25% depending on the USBDIV bit in CKGR_PLLR.
When the PLL output is stable, i.e., the LOCK bit is set:
• The USB device clock can be enabled by setting the UDP bit in PMC_SCER. To save power on this peripheral
when it is not used, the user can set the UDP bit in PMC_SCDR. The UDP bit in PMC_SCSR gives the activity
of this clock. The USB device port require both the 48 MHz signal and the Master Clock. The Master Clock may
be controlled via the Master Clock Controller.
Figure 25-2. USB Clock Controller
25.5 Peripheral Clock Controller
The Power Management Controller controls the clocks of each embedded peripheral by the way of the Peripheral
Clock Controller. The user can individually enable and disable the Master Clock on the peripherals by writing into
the Peripheral Clock Enable (PMC_PCER) and Peripheral Clock Disable (PMC_PCDR) registers. The status of the
peripheral clock activity can be read in the Peripheral Clock Status Register (PMC_PCSR).
When a peripheral clock is disabled, the clock is immediately stopped. The peripheral clocks are automatically dis-
abled after a reset.
In order to stop a peripheral, it is recommended that the system software wait until the peripheral has executed its
last programmed operation before disabling the clock. This is to avoid data corruption or erroneous behavior of the
system.
The bit number within the Peripheral Clock Control registers (PMC_PCER, PMC_PCDR, and PMC_PCSR) is the
Peripheral Identifier defined at the product level. Generally, the bit number corresponds to the interrupt source
number assigned to the peripheral.
25.6 Programmable Clock Output Controller
The PMC controls 3 signals to be output on external pins PCKx. Each signal can be independently programmed
via the PMC_PCKx registers.
PCKx can be independently selected between the Slow clock, the PLL output and the main clock by writing the
CSS field in PMC_PCKx. Each output signal can also be divided by a power of 2 between 1 and 64 by writing the
PRES (Prescaler) field in PMC_PCKx.
USB
Source
Clock
UDP Clock (UDPCK)
UDP
USBDIV
Divider
/1,/2,/4
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Each output signal can be enabled and disabled by writing 1 in the corresponding bit, PCKx of PMC_SCER and
PMC_SCDR, respectively. Status of the active programmable output clocks are given in the PCKx bits of
PMC_SCSR (System Clock Status Register).
Moreover, like the PCK, a status bit in PMC_SR indicates that the Programmable Clock is actually what has been
programmed in the Programmable Clock registers.
As the Programmable Clock Controller does not manage with glitch prevention when switching clocks, it is strongly
recommended to disable the Programmable Clock before any configuration change and to re-enable it after the
change is actually performed.
25.7 Programming Sequence
1. Enabling the Main Oscillator:
The main oscillator is enabled by setting the MOSCEN field in the CKGR_MOR register. In some cases it may
be advantageous to define a start-up time. This can be achieved by writing a value in the OSCOUNT field in
the CKGR_MOR register.
Once this register has been correctly configured, the user must wait for MOSCS field in the PMC_SR register
to be set. This can be done either by polling the status register or by waiting the interrupt line to be raised if the
associated interrupt to MOSCS has been enabled in the PMC_IER register.
Code Example:
write_register(CKGR_MOR,0x00000701)
Start Up Time = 8 * OSCOUNT / SLCK = 56 Slow Clock Cycles.
So, the main oscillator will be enabled (MOSCS bit set) after 56 Slow Clock Cycles.
2. Checking the Main Oscillator Frequency (Optional):
In some situations the user may need an accurate measure of the main oscillator frequency. This measure can
be accomplished via the CKGR_MCFR register.
Once the MAINRDY field is set in CKGR_MCFR register, the user may read the MAINF field in CKGR_MCFR
register. This provides the number of main clock cycles within sixteen slow clock cycles.
3. Setting PLL and divider:
All parameters needed to configure PLL and the divider are located in the CKGR_PLLR register.
The DIV field is used to control divider itself. A value between 0 and 255 can be programmed. Divider output is
divider input divided by DIV parameter. By default DIV parameter is set to 0 which means that divider is turned
off.
The OUT field is used to select the PLL B output frequency range.
The MUL field is the PLL multiplier factor. This parameter can be programmed between 0 and 2047. If MUL is
set to 0, PLL will be turned off, otherwise the PLL output frequency is PLL input frequency multiplied by (MUL +
1).
The PLLCOUNT field specifies the number of slow clock cycles before LOCK bit is set in the PMC_SR register
after CKGR_PLLR register has been written.
Once the PMC_PLL register has been written, the user must wait for the LOCK bit to be set in the PMC_SR
register. This can be done either by polling the status register or by waiting the interrupt line to be raised if the
associated interrupt to LOCK has been enabled in the PMC_IER register. All parameters in CKGR_PLLR can
be programmed in a single write operation. If at some stage one of the following parameters, MUL, DIV is mod-
ified, LOCK bit will go low to indicate that PLL is not ready yet. When PLL is locked, LOCK will be set again.
The user is constrained to wait for LOCK bit to be set before using the PLL output clock.
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The USBDIV field is used to control the additional divider by 1, 2 or 4, which generates the USB clock(s) (Does
not pertain to SAM7S32/16.)
Code Example:
write_register(CKGR_PLLR,0x00040805)
If PLL and divider are enabled, the PLL input clock is the main clock. PLL output clock is PLL input clock multi-
plied by 5. Once CKGR_PLLR has been written, LOCK bit will be set after eight slow clock cycles.
4. Selection of Master Clock and Processor Clock
The Master Clock and the Processor Clock are configurable via the PMC_MCKR register.
The CSS field is used to select the Master Clock divider source. By default, the selected clock source is slow
clock.
The PRES field is used to control the Master Clock prescaler. The user can choose between different values
(1, 2, 4, 8, 16, 32, 64). Master Clock output is prescaler input divided by PRES parameter. By default, PRES
parameter is set to 1 which means that master clock is equal to slow clock.
Once the PMC_MCKR register has been written, the user must wait for the MCKRDY bit to be set in the
PMC_SR register. This can be done either by polling the status register or by waiting for the interrupt line to be
raised if the associated interrupt to MCKRDY has been enabled in the PMC_IER register.
The PMC_MCKR register must not be programmed in a single write operation. The preferred programming
sequence for the PMC_MCKR register is as follows:
• If a new value for CSS field corresponds to PLL Clock,
– Program the PRES field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
– Program the CSS field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
• If a new value for CSS field corresponds to Main Clock or Slow Clock,
– Program the CSS field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
– Program the PRES field in the PMC_MCKR register.
– Wait for the MCKRDY bit to be set in the PMC_SR register.
If at some stage one of the following parameters, CSS or PRES, is modified, the MCKRDY bit will go low to
indicate that the Master Clock and the Processor Clock are not ready yet. The user must wait for MCKRDY bit
to be set again before using the Master and Processor Clocks.
Note: IF PLLx clock was selected as the Master Clock and the user decides to modify it by writing in CKGR_PLLR the
MCKRDY flag will go low while PLL is unlocked. Once PLL is locked again, LOCK goes high and MCKRDY is set.
While PLL is unlocked, the Master Clock selection is automatically changed to Main Clock. For further information, see
Section 25.8.2. “Clock Switching Waveforms” on page 197.
Code Example:
write_register(PMC_MCKR,0x00000001)
wait (MCKRDY=1)
write_register(PMC_MCKR,0x00000011)
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wait (MCKRDY=1)
The Master Clock is main clock divided by 16.
The Processor Clock is the Master Clock.
5. Selection of Programmable clocks
Programmable clocks are controlled via registers; PMC_SCER, PMC_SCDR and PMC_SCSR.
Programmable clocks can be enabled and/or disabled via the PMC_SCER and PMC_SCDR registers.
Depending on the system used, 3 Programmable clocks can be enabled or disabled. The PMC_SCSR pro-
vides a clear indication as to which Programmable clock is enabled. By default all Programmable clocks are
disabled.
PMC_PCKx registers are used to configure Programmable clocks.
The CSS field is used to select the Programmable clock divider source. Four clock options are available: main
clock, slow clock, PLLCK. By default, the clock source selected is slow clock.
The PRES field is used to control the Programmable clock prescaler. It is possible to choose between different
values (1, 2, 4, 8, 16, 32, 64). Programmable clock output is prescaler input divided by PRES parameter. By
default, the PRES parameter is set to 1 which means that master clock is equal to slow clock.
Once the PMC_PCKx register has been programmed, The corresponding Programmable clock must be
enabled and the user is constrained to wait for the PCKRDYx bit to be set in the PMC_SR register. This can be
done either by polling the status register or by waiting the interrupt line to be raised if the associated interrupt to
PCKRDYx has been enabled in the PMC_IER register. All parameters in PMC_PCKx can be programmed in a
single write operation.
If the CSS and PRES parameters are to be modified, the corresponding Programmable clock must be disabled
first. The parameters can then be modified. Once this has been done, the user must re-enable the Programma-
ble clock and wait for the PCKRDYx bit to be set.
Code Example:
write_register(PMC_PCK0,0x00000015)
Programmable clock 0 is main clock divided by 32.
6. Enabling Peripheral Clocks
Once all of the previous steps have been completed, the peripheral clocks can be enabled and/or disabled via
registers PMC_PCER and PMC_PCDR.
Depending on the system used, SAM7S512/256/128/64/321, 12 and for SAM7S32/16, 10 peripheral clocks
can be enabled or disabled. The PMC_PCSR provides a clear view as to which peripheral clock is enabled.
Note: Each enabled peripheral clock corresponds to Master Clock.
Code Examples:
write_register(PMC_PCER,0x00000110)
Peripheral clocks 4 and 8 are enabled.
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write_register(PMC_PCDR,0x00000010)
Peripheral clock 4 is disabled.
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25.8 Clock Switching Details
25.8.1 Master Clock Switching Timings
Table 25-1 gives the worst case timings required for the Master Clock to switch from one selected clock to another
one. This is in the event that the prescaler is de-activated. When the prescaler is activated, an additional time of 64
clock cycles of the new selected clock has to be added.
25.8.2 Clock Switching Waveforms
Figure 25-3. Switch Master Clock from Slow Clock to PLL Clock
Table 25-1. Clock Switching Timings (Worst Case)
From Main Clock SLCK PLL Clock
To
Main Clock – 4 x SLCK +
2.5 x Main Clock
3 x PLL Clock +
4 x SLCK +
1 x Main Clock
SLCK 0.5 x Main Clock +
4.5 x SLCK –3 x PLL Clock +
5 x SLCK
PLL Clock
0.5 x Main Clock +
4 x SLCK +
PLLCOUNT x SLCK +
2.5 x PLLx Clock
2.5 x PLL Clock +
5 x SLCK +
PLLCOUNT x SLCK
2.5 x PLL Clock +
4 x SLCK +
PLLCOUNT x SLCK
Slow Clock
LOCK
MCKRDY
Master Clock
Write PMC_MCKR
PLL Clock
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Figure 25-4. Switch Master Clock from Main Clock to Slow Clock
Figure 25-5. Change PLL Programming
Slow Clock
Main Clock
MCKRDY
Master Clock
Write PMC_MCKR
Main Clock
Main Clock
PLL Clock
LOCK
MCKRDY
Master Clock
Write CKGR_PLLR
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Figure 25-6. Programmable Clock Output Programming
PLL Clock
PCKRDY
PCKx Output
Write PMC_PCKx
Write PMC_SCER
Write PMC_SCDR PCKx is disabled
PCKx is enabled
PLL Clock is selected
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25.9 Power Management Controller (PMC) User Interface
Notes: 1. UDP bit of this register doe not pertain to SAM7S32/16.
2. USBDIV bit of this register does not pertain to SAM7S32/16
Table 25-2. Register Mapping
Offset Register Name Access Reset
0x0000 System Clock Enable Register PMC_SCER(1) Write-only –
0x0004 System Clock Disable Register PMC_SCDR(1) Write-only –
0x0008 System Clock Status Register PMC _SCSR(1) Read-only 0x01
0x000C Reserved – – –
0x0010 Peripheral Clock Enable Register PMC _PCER Write-only –
0x0014 Peripheral Clock Disable Register PMC_PCDR Write-only –
0x0018 Peripheral Clock Status Register PMC_PCSR Read-only 0x0
0x001C Reserved – – –
0x0020 Main Oscillator Register CKGR_MOR Read-write 0x0
0x0024 Main Clock Frequency Register CKGR_MCFR Read-only 0x0
0x0028 Reserved – – –
0x002C PLL Register CKGR_PLLR(2) Read-write 0x3F00
0x0030 Master Clock Register PMC_MCKR Read-write 0x0
0x0038 Reserved – – –
0x003C Reserved – – –
0x0040 Programmable Clock 0 Register PMC_PCK0 Read-write 0x0
0x0044 Programmable Clock 1 Register PMC_PCK1 Read-write 0x0
0x0048 Programmable Clock 2 Register PMC_PCK2 Read-write 0x0
... ... ... ... ...
0x0060 Interrupt Enable Register PMC_IER Write-only --
0x0064 Interrupt Disable Register PMC_IDR Write-only --
0x0068 Status Register PMC_SR Read-only 0x08
0x006C Interrupt Mask Register PMC_IMR Read-only 0x0
0x0070 - 0x007C Reserved – – –
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25.9.1 PMC System Clock Enable Register
Register Name: PMC_SCER
Access Type: Write-only
• PCK: Processor Clock Enable
0 = No effect.
1 = Enables the Processor clock.
• UDP: USB Device Port Clock Enable
0 = No effect.
1 = Enables the 48 MHz clock of the USB Device Port.
(Does not pertain to SAM7S32/16.)
• PCKx: Programmable Clock x Output Enable
0 = No effect.
1 = Enables the corresponding Programmable Clock output.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCK2PCK1PCK0
76543210
UDP––––––PCK
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25.9.2 PMC System Clock Disable Register
Register Name: PMC_SCDR
Access Type: Write-only
• PCK: Processor Clock Disable
0 = No effect.
1 = Disables the Processor clock. This is used to enter the processor in Idle Mode.
• UDP: USB Device Port Clock Disable
0 = No effect.
1 = Disables the 48 MHz clock of the USB Device Port.
(Does not pertain to SAM7S32/16.)
• PCKx: Programmable Clock x Output Disable
0 = No effect.
1 = Disables the corresponding Programmable Clock output.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCK2PCK1PCK0
76543210
UDP––––––PCK
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25.9.3 PMC System Clock Status Register
Register Name: PMC_SCSR
Access Type: Read-only
• PCK: Processor Clock Status
0 = The Processor clock is disabled.
1 = The Processor clock is enabled.
• UDP: USB Device Port Clock Status
0 = The 48 MHz clock (UDPCK) of the USB Device Port is disabled.
1 = The 48 MHz clock (UDPCK) of the USB Device Port is enabled.
(Does not pertain to SAM7S32/16.)
• PCKx: Programmable Clock x Output Status
0 = The corresponding Programmable Clock output is disabled.
1 = The corresponding Programmable Clock output is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCK2PCK1PCK0
76543210
UDP––––––PCK
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25.9.4 PMC Peripheral Clock Enable Register
Register Name: PMC_PCER
Access Type: Write-only
• PIDx: Peripheral Clock x Enable
0 = No effect.
1 = Enables the corresponding peripheral clock.
Note: PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
Note: Programming the control bits of the Peripheral ID that are not implemented has no effect on the behavior of the PMC.
25.9.5 PMC Peripheral Clock Disable Register
Register Name: PMC_PCDR
Access Type: Write-only
• PIDx: Peripheral Clock x Disable
0 = No effect.
1 = Disables the corresponding peripheral clock.
Note: PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 - -
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 - -
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25.9.6 PMC Peripheral Clock Status Register
Register Name: PMC_PCSR
Access Type: Read-only
• PIDx: Peripheral Clock x Status
0 = The corresponding peripheral clock is disabled.
1 = The corresponding peripheral clock is enabled.
Note: PID2 to PID31 refer to identifiers as defined in the section “Peripheral Identifiers” in the product datasheet.
31 30 29 28 27 26 25 24
PID31 PID30 PID29 PID28 PID27 PID26 PID25 PID24
23 22 21 20 19 18 17 16
PID23 PID22 PID21 PID20 PID19 PID18 PID17 PID16
15 14 13 12 11 10 9 8
PID15 PID14 PID13 PID12 PID11 PID10 PID9 PID8
76543210
PID7 PID6 PID5 PID4 PID3 PID2 – –
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25.9.7 PMC Clock Generator Main Oscillator Register
Register Name: CKGR_MOR
Access Type: Read-write
• MOSCEN: Main Oscillator Enable
A crystal must be connected between XIN and XOUT.
0 = The Main Oscillator is disabled.
1 = The Main Oscillator is enabled. OSCBYPASS must be set to 0.
When MOSCEN is set, the MOSCS flag is set once the Main Oscillator startup time is achieved.
• OSCBYPASS: Oscillator Bypass
0 = No effect.
1 = The Main Oscillator is bypassed. MOSCEN must be set to 0. An external clock must be connected on XIN.
When OSCBYPASS is set, the MOSCS flag in PMC_SR is automatically set.
Clearing MOSCEN and OSCBYPASS bits allows resetting the MOSCS flag.
• OSCOUNT: Main Oscillator Start-up Time
Specifies the number of Slow Clock cycles multiplied by 8 for the Main Oscillator start-up time.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
OSCOUNT
76543210
––––––OSCBYPASSMOSCEN
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25.9.8 PMC Clock Generator Main Clock Frequency Register
Register Name: CKGR_MCFR
Access Type: Read-only
• MAINF: Main Clock Frequency
Gives the number of Main Clock cycles within 16 Slow Clock periods.
• MAINRDY: Main Clock Ready
0 = MAINF value is not valid or the Main Oscillator is disabled.
1 = The Main Oscillator has been enabled previously and MAINF value is available.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–––––––MAINRDY
15 14 13 12 11 10 9 8
MAINF
76543210
MAINF
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25.9.9 PMC Clock Generator PLL Register
Register Name: CKGR_PLLR
Access Type: Read-write
Possible limitations on PLL input frequencies and multiplier factors should be checked before using the PMC.
•DIV: Divider
• PLLCOUNT: PLL Counter
Specifies the number of slow clock cycles before the LOCK bit is set in PMC_SR after CKGR_PLLR is written.
• OUT: PLL Clock Frequency Range
To optimize clock performance, this field must be programmed as specified in “PLL Characteristics” in the Electrical Char-
acteristics section of the product datasheet.
• MUL: PLL Multiplier
0 = The PLL is deactivated.
1 up to 2047 = The PLL Clock frequency is the PLL input frequency multiplied by MUL+ 1.
• USBDIV: Divider for USB Clock (Does not Pertain to SAM73S2/16
31 30 29 28 27 26 25 24
– – USBDIV – MUL
23 22 21 20 19 18 17 16
MUL
15 14 13 12 11 10 9 8
OUT PLLCOUNT
76543210
DIV
DIV Divider Selected
0 Divider output is 0
1 Divider is bypassed
2 - 255 Divider output is the selected clock divided by DIV.
USBDIV Divider for USB Clock(s)
0 0 Divider output is PLL clock output.
0 1 Divider output is PLL clock output divided by 2.
1 0 Divider output is PLL clock output divided by 4.
1 1 Reserved.
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25.9.10 PMC Master Clock Register
Register Name: PMC_MCKR
Access Type: Read-write
• CSS: Master Clock Selection
• PRES: Processor Clock Prescaler
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
– – – PRES CSS
CSS Clock Source Selection
0 0 Slow Clock is selected
0 1 Main Clock is selected
10Reserved
1 1 PLL Clock is selected.
PRES Processor Clock
0 0 0 Selected clock
0 0 1 Selected clock divided by 2
0 1 0 Selected clock divided by 4
0 1 1 Selected clock divided by 8
1 0 0 Selected clock divided by 16
1 0 1 Selected clock divided by 32
1 1 0 Selected clock divided by 64
111Reserved
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25.9.11 PMC Programmable Clock Register
Register Name: PMC_PCKx
Access Type: Read-write
• CSS: Master Clock Selection
• PRES: Programmable Clock Prescaler
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
– – – PRES CSS
CSS Clock Source Selection
0 0 Slow Clock is selected
0 1 Main Clock is selected
10Reserved
1 1 PLL Clock is selected
PRES Programmable Clock
0 0 0 Selected clock
0 0 1 Selected clock divided by 2
0 1 0 Selected clock divided by 4
0 1 1 Selected clock divided by 8
1 0 0 Selected clock divided by 16
1 0 1 Selected clock divided by 32
1 1 0 Selected clock divided by 64
111Reserved
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25.9.12 PMC Interrupt Enable Register
Register Name: PMC_IER
Access Type: Write-only
• MOSCS: Main Oscillator Status Interrupt Enable
• LOCK: PLL Lock Interrupt Enable
• MCKRDY: Master Clock Ready Interrupt Enable
• PCKRDYx: Programmable Clock Ready x Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCKRDY2PCKRDY1PCKRDY0
76543210
––––MCKRDYLOCK–MOSCS
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25.9.13 PMC Interrupt Disable Register
Register Name: PMC_IDR
Access Type: Write-only
• MOSCS: Main Oscillator Status Interrupt Disable
• LOCK: PLL Lock Interrupt Disable
• MCKRDY: Master Clock Ready Interrupt Disable
• PCKRDYx: Programmable Clock Ready x Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCKRDY2PCKRDY1PCKRDY0
76543210
––––MCKRDY
LOCK – MOSCS
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25.9.14 PMC Status Register
Register Name: PMC_SR
Access Type: Read-only
• MOSCS: MOSCS Flag Status
0 = Main oscillator is not stabilized.
1 = Main oscillator is stabilized.
• LOCK: PLL Lock Status
0 = PLL is not locked
1 = PLL is locked.
• MCKRDY: Master Clock Status
0 = Master Clock is not ready.
1 = Master Clock is ready.
• PCKRDYx: Programmable Clock Ready Status
0 = Programmable Clock x is not ready.
1 = Programmable Clock x is ready.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCKRDY2PCKRDY1PCKRDY0
76543210
––––MCKRDY
LOCK – MOSCS
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25.9.15 PMC Interrupt Mask Register
Register Name: PMC_IMR
Access Type: Read-only
• MOSCS: Main Oscillator Status Interrupt Mask
• LOCK: PLL Lock Interrupt Mask
• MCKRDY: Master Clock Ready Interrupt Mask
• PCKRDYx: Programmable Clock Ready x Interrupt Mask
0 = The corresponding interrupt is enabled.
1 = The corresponding interrupt is disabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––PCKRDY2PCKRDY1PCKRDY0
76543210
––––MCKRDY
LOCK – MOSCS
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26. Debug Unit (DBGU)
26.1 Overview
The Debug Unit provides a single entry point from the processor for access to all the debug capabilities of Atmel’s
ARM-based systems.
The Debug Unit features a two-pin UART that can be used for several debug and trace purposes and offers an
ideal medium for in-situ programming solutions and debug monitor communications. Moreover, the association
with two peripheral data controller channels permits packet handling for these tasks with processor time reduced to
a minimum.
The Debug Unit also makes the Debug Communication Channel (DCC) signals provided by the In-circuit Emulator
of the ARM processor visible to the software. These signals indicate the status of the DCC read and write registers
and generate an interrupt to the ARM processor, making possible the handling of the DCC under interrupt control.
Chip Identifier registers permit recognition of the device and its revision. These registers inform as to the sizes and
types of the on-chip memories, as well as the set of embedded peripherals.
Finally, the Debug Unit features a Force NTRST capability that enables the software to decide whether to prevent
access to the system via the In-circuit Emulator. This permits protection of the code, stored in ROM.
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26.2 Block Diagram
Figure 26-1. Debug Unit Functional Block Diagram
Debug Unit Application Example
Peripheral DMA Controller
Baud Rate
Generator
DCC
Handler
ICE
Access
Handler
Transmit
Receive
Chip ID
Interrupt
Control
Peripheral
Bridge
Parallel
Input/
Output
DTXD
DRXD
Power
Management
Controller
ARM
Processor
force_ntrst
COMMRX
COMMTX
MCK
nTRST
Power-on
Reset
dbgu_irq
APB Debug Unit
R
Table 26-1. Debug Unit Pin Description
Pin Name Description Type
DRXD Debug Receive Data Input
DTXD Debug Transmit Data Output
Debug Unit
RS232 Drivers
Programming Tool Trace Console Debug Console
Boot Program Debug Monitor Trace Manager
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26.3 Product Dependencies
26.3.1 I/O Lines
Depending on product integration, the Debug Unit pins may be multiplexed with PIO lines. In this case, the pro-
grammer must first configure the corresponding PIO Controller to enable I/O lines operations of the Debug Unit.
26.3.2 Power Management
Depending on product integration, the Debug Unit clock may be controllable through the Power Management Con-
troller. In this case, the programmer must first configure the PMC to enable the Debug Unit clock. Usually, the
peripheral identifier used for this purpose is 1.
26.3.3 Interrupt Source
Depending on product integration, the Debug Unit interrupt line is connected to one of the interrupt sources of the
Advanced Interrupt Controller. Interrupt handling requires programming of the AIC before configuring the Debug
Unit. Usually, the Debug Unit interrupt line connects to the interrupt source 1 of the AIC, which may be shared with
the real-time clock, the system timer interrupt lines and other system peripheral interrupts, as shown in Figure 26-
1. This sharing requires the programmer to determine the source of the interrupt when the source 1 is triggered.
26.4 UART Operations
The Debug Unit operates as a UART, (asynchronous mode only) and supports only 8-bit character handling (with
parity). It has no clock pin.
The Debug Unit's UART is made up of a receiver and a transmitter that operate independently, and a common
baud rate generator. Receiver timeout and transmitter time guard are not implemented. However, all the imple-
mented features are compatible with those of a standard USART.
26.4.1 Baud Rate Generator
The baud rate generator provides the bit period clock named baud rate clock to both the receiver and the
transmitter.
The baud rate clock is the master clock divided by 16 times the value (CD) written in DBGU_BRGR (Baud Rate
Generator Register). If DBGU_BRGR is set to 0, the baud rate clock is disabled and the Debug Unit's UART
remains inactive. The maximum allowable baud rate is Master Clock divided by 16. The minimum allowable baud
rate is Master Clock divided by (16 x 65536).
Figure 26-2. Baud Rate Generator
Baud Rate MCK
16 CD×
----------------------=
MCK 16-bit Counter
0
Baud Rate
Clock
CD
CD
OUT
Divide
by 16
0
1
>1
Receiver
Sampling Clock
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26.4.2 Receiver
26.4.2.1 Receiver Reset, Enable and Disable
After device reset, the Debug Unit receiver is disabled and must be enabled before being used. The receiver can
be enabled by writing the control register DBGU_CR with the bit RXEN at 1. At this command, the receiver starts
looking for a start bit.
The programmer can disable the receiver by writing DBGU_CR with the bit RXDIS at 1. If the receiver is waiting for
a start bit, it is immediately stopped. However, if the receiver has already detected a start bit and is receiving the
data, it waits for the stop bit before actually stopping its operation.
The programmer can also put the receiver in its reset state by writing DBGU_CR with the bit RSTRX at 1. In doing
so, the receiver immediately stops its current operations and is disabled, whatever its current state. If RSTRX is
applied when data is being processed, this data is lost.
26.4.2.2 Start Detection and Data Sampling
The Debug Unit only supports asynchronous operations, and this affects only its receiver. The Debug Unit receiver
detects the start of a received character by sampling the DRXD signal until it detects a valid start bit. A low level
(space) on DRXD is interpreted as a valid start bit if it is detected for more than 7 cycles of the sampling clock,
which is 16 times the baud rate. Hence, a space that is longer than 7/16 of the bit period is detected as a valid start
bit. A space which is 7/16 of a bit period or shorter is ignored and the receiver continues to wait for a valid start bit.
When a valid start bit has been detected, the receiver samples the DRXD at the theoretical midpoint of each bit. It
is assumed that each bit lasts 16 cycles of the sampling clock (1-bit period) so the bit sampling point is eight cycles
(0.5-bit period) after the start of the bit. The first sampling point is therefore 24 cycles (1.5-bit periods) after the fall-
ing edge of the start bit was detected.
Each subsequent bit is sampled 16 cycles (1-bit period) after the previous one.
Figure 26-3. Start Bit Detection
Figure 26-4. Character Reception
26.4.2.3 Receiver Ready
When a complete character is received, it is transferred to the DBGU_RHR and the RXRDY status bit in
DBGU_SR (Status Register) is set. The bit RXRDY is automatically cleared when the receive holding register
DBGU_RHR is read.
Sampling Clock
DRXD
True Start
Detection
D0
Baud Rate
Clock
D0 D1 D2 D3 D4 D5 D6 D7
DRXD
True Start Detection
Sampling
Parity Bit
Stop Bit
Example: 8-bit, parity enabled 1 stop
1 bit
period
0.5 bit
period
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Figure 26-5. Receiver Ready
26.4.2.4 Receiver Overrun
If DBGU_RHR has not been read by the software (or the Peripheral Data Controller) since the last transfer, the
RXRDY bit is still set and a new character is received, the OVRE status bit in DBGU_SR is set. OVRE is cleared
when the software writes the control register DBGU_CR with the bit RSTSTA (Reset Status) at 1.
Figure 26-6. Receiver Overrun
26.4.2.5 Parity Error
Each time a character is received, the receiver calculates the parity of the received data bits, in accordance with
the field PAR in DBGU_MR. It then compares the result with the received parity bit. If different, the parity error bit
PARE in DBGU_SR is set at the same time the RXRDY is set. The parity bit is cleared when the control register
DBGU_CR is written with the bit RSTSTA (Reset Status) at 1. If a new character is received before the reset status
command is written, the PARE bit remains at 1.
Figure 26-7. Parity Error
26.4.2.6 Receiver Framing Error
When a start bit is detected, it generates a character reception when all the data bits have been sampled. The stop
bit is also sampled and when it is detected at 0, the FRAME (Framing Error) bit in DBGU_SR is set at the same
time the RXRDY bit is set. The bit FRAME remains high until the control register DBGU_CR is written with the bit
RSTSTA at 1.
D0 D1 D2 D3 D4 D5 D6 D7 PS SD0 D1 D2 D3 D4 D5 D6 D7 P
DRXD
Read DBGU_RHR
RXRDY
D0 D1 D2 D3 D4 D5 D6 D7 PS SD0 D1 D2 D3 D4 D5 D6 D7 P
DRXD
RSTSTA
RXRDY
OVRE
stop stop
stop
D0 D1 D2 D3 D4 D5 D6 D7 PS
DRXD
RSTSTA
RXRDY
PARE
Wrong Parity Bit
220
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Figure 26-8. Receiver Framing Error
26.4.3 Transmitter
26.4.3.1 Transmitter Reset, Enable and Disable
After device reset, the Debug Unit transmitter is disabled and it must be enabled before being used. The transmit-
ter is enabled by writing the control register DBGU_CR with the bit TXEN at 1. From this command, the transmitter
waits for a character to be written in the Transmit Holding Register DBGU_THR before actually starting the
transmission.
The programmer can disable the transmitter by writing DBGU_CR with the bit TXDIS at 1. If the transmitter is not
operating, it is immediately stopped. However, if a character is being processed into the Shift Register and/or a
character has been written in the Transmit Holding Register, the characters are completed before the transmitter is
actually stopped.
The programmer can also put the transmitter in its reset state by writing the DBGU_CR with the bit RSTTX at 1.
This immediately stops the transmitter, whether or not it is processing characters.
26.4.3.2 Transmit Format
The Debug Unit transmitter drives the pin DTXD at the baud rate clock speed. The line is driven depending on the
format defined in the Mode Register and the data stored in the Shift Register. One start bit at level 0, then the 8
data bits, from the lowest to the highest bit, one optional parity bit and one stop bit at 1 are consecutively shifted out
as shown on the following figure. The field PARE in the mode register DBGU_MR defines whether or not a parity
bit is shifted out. When a parity bit is enabled, it can be selected between an odd parity, an even parity, or a fixed
space or mark bit.
Figure 26-9. Character Transmission
26.4.3.3 Transmitter Control
When the transmitter is enabled, the bit TXRDY (Transmitter Ready) is set in the status register DBGU_SR. The
transmission starts when the programmer writes in the Transmit Holding Register DBGU_THR, and after the writ-
ten character is transferred from DBGU_THR to the Shift Register. The bit TXRDY remains high until a second
character is written in DBGU_THR. As soon as the first character is completed, the last character written in
DBGU_THR is transferred into the shift register and TXRDY rises again, showing that the holding register is empty.
When both the Shift Register and the DBGU_THR are empty, i.e., all the characters written in DBGU_THR have
been processed, the bit TXEMPTY rises after the last stop bit has been completed.
D0 D1 D2 D3 D4 D5 D6 D7 PS
DRXD
RSTSTA
RXRDY
FRAME
Stop Bit
Detected at 0
stop
D0 D1 D2 D3 D4 D5 D6 D7
DTXD
Start
Bit
Parity
Bit
Stop
Bit
Example: Parity enabled
Baud Rate
Clock
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Figure 26-10. Transmitter Control
26.4.4 Peripheral Data Controller
Both the receiver and the transmitter of the Debug Unit's UART are generally connected to a Peripheral Data Con-
troller (PDC) channel.
The peripheral data controller channels are programmed via registers that are mapped within the Debug Unit user
interface from the offset 0x100. The status bits are reported in the Debug Unit status register DBGU_SR and can
generate an interrupt.
The RXRDY bit triggers the PDC channel data transfer of the receiver. This results in a read of the data in
DBGU_RHR. The TXRDY bit triggers the PDC channel data transfer of the transmitter. This results in a write of a
data in DBGU_THR.
26.4.5 Test Modes
The Debug Unit supports three tests modes. These modes of operation are programmed by using the field
CHMODE (Channel Mode) in the mode register DBGU_MR.
The Automatic Echo mode allows bit-by-bit retransmission. When a bit is received on the DRXD line, it is sent to
the DTXD line. The transmitter operates normally, but has no effect on the DTXD line.
The Local Loopback mode allows the transmitted characters to be received. DTXD and DRXD pins are not used
and the output of the transmitter is internally connected to the input of the receiver. The DRXD pin level has no
effect and the DTXD line is held high, as in idle state.
The Remote Loopback mode directly connects the DRXD pin to the DTXD line. The transmitter and the receiver
are disabled and have no effect. This mode allows a bit-by-bit retransmission.
DBGU_THR
Shift Register
DTXD
TXRDY
TXEMPTY
Data 0 Data 1
Data 0
Data 0
Data 1
Data 1S SPP
Write Data 0
in DBGU_THR
Write Data 1
in DBGU_THR
stop
stop
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Figure 26-11. Test Modes
26.4.6 Debug Communication Channel Support
The Debug Unit handles the signals COMMRX and COMMTX that come from the Debug Communication Channel
of the ARM Processor and are driven by the In-circuit Emulator.
The Debug Communication Channel contains two registers that are accessible through the ICE Breaker on the
JTAG side and through the coprocessor 0 on the ARM Processor side.
As a reminder, the following instructions are used to read and write the Debug Communication Channel:
MRC p14, 0, Rd, c1, c0, 0
Returns the debug communication data read register into Rd
MCR p14, 0, Rd, c1, c0, 0
Writes the value in Rd to the debug communication data write register.
The bits COMMRX and COMMTX, which indicate, respectively, that the read register has been written by the
debugger but not yet read by the processor, and that the write register has been written by the processor and not
yet read by the debugger, are wired on the two highest bits of the status register DBGU_SR. These bits can gener-
ate an interrupt. This feature permits handling under interrupt a debug link between a debug monitor running on the
target system and a debugger.
26.4.7 Chip Identifier
The Debug Unit features two chip identifier registers, DBGU_CIDR (Chip ID Register) and DBGU_EXID (Extension
ID). Both registers contain a hard-wired value that is read-only. The first register contains the following fields:
Receiver
Transmitter Disabled
RXD
TXD
Receiver
Transmitter Disabled
RXD
TXD
VDD
Disabled
Receiver
Transmitter Disabled
RXD
TXD
Disabled
Automatic Echo
Local Loopback
Remote Loopback VDD
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• EXT - shows the use of the extension identifier register
• NVPTYP and NVPSIZ - identifies the type of embedded non-volatile memory and its size
• ARCH - identifies the set of embedded peripheral
• SRAMSIZ - indicates the size of the embedded SRAM
• EPROC - indicates the embedded ARM processor
• VERSION - gives the revision of the silicon
The second register is device-dependent and reads 0 if the bit EXT is 0.
26.4.8 ICE Access Prevention
The Debug Unit allows blockage of access to the system through the ARM processor's ICE interface. This feature
is implemented via the register Force NTRST (DBGU_FNR), that allows assertion of the NTRST signal of the ICE
Interface. Writing the bit FNTRST (Force NTRST) to 1 in this register prevents any activity on the TAP controller.
On standard devices, the FNTRST bit resets to 0 and thus does not prevent ICE access.
This feature is especially useful on custom ROM devices for customers who do not want their on-chip code to be
visible.
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26.5 Debug Unit (DBGU) User Interface
Table 26-2. Memory Mapping
Offset Register Name Access Reset
0x0000 Control Register DBGU_CR Write-only –
0x0004 Mode Register DBGU_MR Read-write 0x0
0x0008 Interrupt Enable Register DBGU_IER Write-only –
0x000C Interrupt Disable Register DBGU_IDR Write-only –
0x0010 Interrupt Mask Register DBGU_IMR Read-only 0x0
0x0014 Status Register DBGU_SR Read-only –
0x0018 Receive Holding Register DBGU_RHR Read-only 0x0
0x001C Transmit Holding Register DBGU_THR Write-only –
0x0020 Baud Rate Generator Register DBGU_BRGR Read-write 0x0
0x0024 - 0x003C Reserved – – –
0x0040 Chip ID Register DBGU_CIDR Read-only –
0x0044 Chip ID Extension Register DBGU_EXID Read-only –
0x0048 Force NTRST Register DBGU_FNR Read-write 0x0
0x004C - 0x00FC Reserved – – –
0x0100 - 0x0124 PDC Area – – –
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26.5.1 Debug Unit Control Register
Name: DBGU_CR
Access Type: Write-only
• RSTRX: Reset Receiver
0 = No effect.
1 = The receiver logic is reset and disabled. If a character is being received, the reception is aborted.
• RSTTX: Reset Transmitter
0 = No effect.
1 = The transmitter logic is reset and disabled. If a character is being transmitted, the transmission is aborted.
• RXEN: Receiver Enable
0 = No effect.
1 = The receiver is enabled if RXDIS is 0.
• RXDIS: Receiver Disable
0 = No effect.
1 = The receiver is disabled. If a character is being processed and RSTRX is not set, the character is completed before the
receiver is stopped.
• TXEN: Transmitter Enable
0 = No effect.
1 = The transmitter is enabled if TXDIS is 0.
• TXDIS: Transmitter Disable
0 = No effect.
1 = The transmitter is disabled. If a character is being processed and a character has been written the DBGU_THR and
RSTTX is not set, both characters are completed before the transmitter is stopped.
• RSTSTA: Reset Status Bits
0 = No effect.
1 = Resets the status bits PARE, FRAME and OVRE in the DBGU_SR.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––
RSTSTA
76543210
TXDIS TXEN RXDIS RXEN RSTTX RSTRX ––
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26.5.2 Debug Unit Mode Register
Name: DBGU_MR
Access Type: Read-write
• PAR: Parity Type
• CHMODE: Channel Mode
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
CHMODE –– PAR –
76543210
––––––––
PAR Parity Type
0 0 0 Even parity
001Odd parity
0 1 0 Space: parity forced to 0
0 1 1 Mark: parity forced to 1
1 x x No parity
CHMODE Mode Description
00Normal Mode
0 1 Automatic Echo
1 0 Local Loopback
1 1 Remote Loopback
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26.5.3 Debug Unit Interrupt Enable Register
Name: DBGU_IER
Access Type: Write-only
• RXRDY: Enable RXRDY Interrupt
• TXRDY: Enable TXRDY Interrupt
• ENDRX: Enable End of Receive Transfer Interrupt
• ENDTX: Enable End of Transmit Interrupt
• OVRE: Enable Overrun Error Interrupt
• FRAME: Enable Framing Error Interrupt
• PARE: Enable Parity Error Interrupt
• TXEMPTY: Enable TXEMPTY Interrupt
• TXBUFE: Enable Buffer Empty Interrupt
• RXBUFF: Enable Buffer Full Interrupt
• COMMTX: Enable COMMTX (from ARM) Interrupt
• COMMRX: Enable COMMRX (from ARM) Interrupt
0 = No effect.
1 = Enables the corresponding interrupt.
31 30 29 28 27 26 25 24
COMMRX COMMTX ––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––
RXBUFF TXBUFE –TXEMPTY –
76543210
PARE FRAME OVRE ENDTX ENDRX –TXRDY RXRDY
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26.5.4 Debug Unit Interrupt Disable Register
Name: DBGU_IDR
Access Type: Write-only
• RXRDY: Disable RXRDY Interrupt
• TXRDY: Disable TXRDY Interrupt
• ENDRX: Disable End of Receive Transfer Interrupt
• ENDTX: Disable End of Transmit Interrupt
• OVRE: Disable Overrun Error Interrupt
• FRAME: Disable Framing Error Interrupt
• PARE: Disable Parity Error Interrupt
• TXEMPTY: Disable TXEMPTY Interrupt
• TXBUFE: Disable Buffer Empty Interrupt
• RXBUFF: Disable Buffer Full Interrupt
• COMMTX: Disable COMMTX (from ARM) Interrupt
• COMMRX: Disable COMMRX (from ARM) Interrupt
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
COMMRX COMMTX ––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––
RXBUFF TXBUFE –TXEMPTY –
76543210
PARE FRAME OVRE ENDTX ENDRX –TXRDY RXRDY
229
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26.5.5 Debug Unit Interrupt Mask Register
Name: DBGU_IMR
Access Type: Read-only
• RXRDY: Mask RXRDY Interrupt
• TXRDY: Disable TXRDY Interrupt
• ENDRX: Mask End of Receive Transfer Interrupt
• ENDTX: Mask End of Transmit Interrupt
• OVRE: Mask Overrun Error Interrupt
• FRAME: Mask Framing Error Interrupt
• PARE: Mask Parity Error Interrupt
• TXEMPTY: Mask TXEMPTY Interrupt
• TXBUFE: Mask TXBUFE Interrupt
• RXBUFF: Mask RXBUFF Interrupt
• COMMTX: Mask COMMTX Interrupt
• COMMRX: Mask COMMRX Interrupt
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
31 30 29 28 27 26 25 24
COMMRX COMMTX ––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––
RXBUFF TXBUFE –TXEMPTY –
76543210
PARE FRAME OVRE ENDTX ENDRX –TXRDY RXRDY
230
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
26.5.6 Debug Unit Status Register
Name: DBGU_SR
Access Type: Read-only
• RXRDY: Receiver Ready
0 = No character has been received since the last read of the DBGU_RHR or the receiver is disabled.
1 = At least one complete character has been received, transferred to DBGU_RHR and not yet read.
• TXRDY: Transmitter Ready
0 = A character has been written to DBGU_THR and not yet transferred to the Shift Register, or the transmitter is disabled.
1 = There is no character written to DBGU_THR not yet transferred to the Shift Register.
• ENDRX: End of Receiver Transfer
0 = The End of Transfer signal from the receiver Peripheral Data Controller channel is inactive.
1 = The End of Transfer signal from the receiver Peripheral Data Controller channel is active.
• ENDTX: End of Transmitter Transfer
0 = The End of Transfer signal from the transmitter Peripheral Data Controller channel is inactive.
1 = The End of Transfer signal from the transmitter Peripheral Data Controller channel is active.
• OVRE: Overrun Error
0 = No overrun error has occurred since the last RSTSTA.
1 = At least one overrun error has occurred since the last RSTSTA.
• FRAME: Framing Error
0 = No framing error has occurred since the last RSTSTA.
1 = At least one framing error has occurred since the last RSTSTA.
• PARE: Parity Error
0 = No parity error has occurred since the last RSTSTA.
1 = At least one parity error has occurred since the last RSTSTA.
• TXEMPTY: Transmitter Empty
0 = There are characters in DBGU_THR, or characters being processed by the transmitter, or the transmitter is disabled.
1 = There are no characters in DBGU_THR and there are no characters being processed by the transmitter.
• TXBUFE: Transmission Buffer Empty
31 30 29 28 27 26 25 24
COMMRX COMMTX ––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––
RXBUFF TXBUFE –TXEMPTY –
76543210
PARE FRAME OVRE ENDTX ENDRX –TXRDY RXRDY
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6175M–ATARM–26-Oct-12
0 = The buffer empty signal from the transmitter PDC channel is inactive.
1 = The buffer empty signal from the transmitter PDC channel is active.
• RXBUFF: Receive Buffer Full
0 = The buffer full signal from the receiver PDC channel is inactive.
1 = The buffer full signal from the receiver PDC channel is active.
• COMMTX: Debug Communication Channel Write Status
0 = COMMTX from the ARM processor is inactive.
1 = COMMTX from the ARM processor is active.
• COMMRX: Debug Communication Channel Read Status
0 = COMMRX from the ARM processor is inactive.
1 = COMMRX from the ARM processor is active.
232
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26.5.7 Debug Unit Receiver Holding Register
Name: DBGU_RHR
Access Type: Read-only
• RXCHR: Received Character
Last received character if RXRDY is set.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
RXCHR
233
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26.5.8 Debug Unit Transmit Holding Register
Name: DBGU_THR
Access Type: Write-only
• TXCHR: Character to be Transmitted
Next character to be transmitted after the current character if TXRDY is not set.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
TXCHR
234
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26.5.9 Debug Unit Baud Rate Generator Register
Name: DBGU_BRGR
Access Type: Read-write
• CD: Clock Divisor
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
CD
76543210
CD
CD Baud Rate Clock
0 Disabled
1MCK
2 to 65535 MCK / (CD x 16)
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26.5.10 Debug Unit Chip ID Register
Name: DBGU_CIDR
Access Type: Read-only
• VERSION: Version of the Device
• EPROC: Embedded Processor
• NVPSIZ: Nonvolatile Program Memory Size
31 30 29 28 27 26 25 24
EXT NVPTYP ARCH
23 22 21 20 19 18 17 16
ARCH SRAMSIZ
15 14 13 12 11 10 9 8
NVPSIZ2 NVPSIZ
76543210
EPROC VERSION
EPROC Processor
0 0 1 ARM946ES™
0 1 0 ARM7TDMI®
100ARM920T
™
1 0 1 ARM926EJS™
NVPSIZ Size
0000None
00018K bytes
001016K bytes
001132K bytes
0100Reserved
010164K bytes
0110Reserved
0111128K bytes
1000Reserved
1001256K bytes
1010512K bytes
1011Reserved
11001024K bytes
1101Reserved
11102048K bytes
1111Reserved
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• NVPSIZ2 Second Nonvolatile Program Memory Size
• SRAMSIZ: Internal SRAM Size
NVPSIZ2 Size
0000None
00018K bytes
001016K bytes
001132K bytes
0100Reserved
010164K bytes
0110Reserved
0111128K bytes
1000Reserved
1001256K bytes
1010512K bytes
1011Reserved
11001024K bytes
1101Reserved
11102048K bytes
1111Reserved
SRAMSIZ Size
0000Reserved
00011K bytes
00102K bytes
00116K bytes
0100112K bytes
01014K bytes
011080K bytes
0111160K bytes
10008K bytes
100116K bytes
101032K bytes
101164K bytes
1100128K bytes
1101256K bytes
111096K bytes
1111512K bytes
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• ARCH: Architecture Identifier
• NVPTYP: Nonvolatile Program Memory Type
• EXT: Extension Flag
0 = Chip ID has a single register definition without extension
1 = An extended Chip ID exists.
ARCH
ArchitectureHex Bin
0x19 0001 1001 AT91SAM9xx Series
0x29 0010 1001 AT91SAM9XExx Series
0x34 0011 0100 AT91x34 Series
0x37 0011 0111 CAP7 Series
0x39 0011 1001 CAP9 Series
0x3B 0011 1011 CAP11 Series
0x40 0100 0000 AT91x40 Series
0x42 0100 0010 AT91x42 Series
0x55 0101 0101 AT91x55 Series
0x60 0110 0000 AT91SAM7Axx Series
0x61 0110 0001 AT91SAM7AQxx Series
0x63 0110 0011 AT91x63 Series
0x70 0111 0000 AT91SAM7Sxx Series
0x71 0111 0001 AT91SAM7XCxx Series
0x72 0111 0010 AT91SAM7SExx Series
0x73 0111 0011 AT91SAM7Lxx Series
0x75 0111 0101 AT91SAM7Xxx Series
0x92 1001 0010 AT91x92 Series
0xF0 1111 0000 AT75Cxx Series
NVPTYP Memory
000ROM
0 0 1 ROMless or on-chip Flash
1 0 0 SRAM emulating ROM
0 1 0 Embedded Flash Memory
011
ROM and Embedded Flash Memory
NVPSIZ is ROM size
NVPSIZ2 is Flash size
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26.5.11 Debug Unit Chip ID Extension Register
Name: DBGU_EXID
Access Type: Read-only
• EXID: Chip ID Extension
Reads 0 if the bit EXT in DBGU_CIDR is 0.
26.5.12 Debug Unit Force NTRST Register
Name: DBGU_FNR
Access Type: Read-write
• FNTRST: Force NTRST
0 = NTRST of the ARM processor’s TAP controller is driven by the power_on_reset signal.
1 = NTRST of the ARM processor’s TAP controller is held low.
31 30 29 28 27 26 25 24
EXID
23 22 21 20 19 18 17 16
EXID
15 14 13 12 11 10 9 8
EXID
76543210
EXID
31 30 29 28 27 26 25 24
––––––– –
23 22 21 20 19 18 17 16
––––––– –
15 14 13 12 11 10 9 8
––––––– –
7654321 0
–––––––
FNTRST
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27. Parallel Input/Output Controller (PIO)
27.1 Overview
The Parallel Input/Output Controller (PIO) manages up to 32 fully programmable input/output
lines. Each I/O line may be dedicated as a general-purpose I/O or be assigned to a function of
an embedded peripheral. This assures effective optimization of the pins of a product.
Each I/O line is associated with a bit number in all of the 32-bit registers of the 32-bit wide User
Interface.
Each I/O line of the PIO Controller features:
• An input change interrupt enabling level change detection on any I/O line.
• A glitch filter providing rejection of pulses lower than one-half of clock cycle.
• Multi-drive capability similar to an open drain I/O line.
• Control of the pull-up of the I/O line.
• Input visibility and output control.
The PIO Controller also features a synchronous output providing up to 32 bits of data output in a
single write operation.
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27.2 Block Diagram
Figure 27-1. Block Diagram
Figure 27-2. Application Block Diagram
Embedded
Peripheral
Embedded
Peripheral
PIO Interrupt
PIO Controller
Up to 32 pins
PMC
Up to 32
peripheral IOs
Up to 32
peripheral IOs
PIO Clock
APB
AIC
Data, Enable
PIN 31
PIN 1
PIN 0
Data, Enable
On-Chip Peripherals
PIO Controller
On-Chip Peripheral Drivers
Control & Command
Driver
Keyboard Driver
Keyboard Driver General Purpose I/Os External Devices
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27.3 Product Dependencies
27.3.1 Pin Multiplexing
Each pin is configurable, according to product definition as either a general-purpose I/O line
only, or as an I/O line multiplexed with one or two peripheral I/Os. As the multiplexing is hard-
ware-defined and thus product-dependent, the hardware designer and programmer must
carefully determine the configuration of the PIO controllers required by their application. When
an I/O line is general-purpose only, i.e. not multiplexed with any peripheral I/O, programming of
the PIO Controller regarding the assignment to a peripheral has no effect and only the PIO Con-
troller can control how the pin is driven by the product.
27.3.2 External Interrupt Lines
The interrupt signals FIQ and IRQ0 to IRQn are most generally multiplexed through the PIO
Controllers. However, it is not necessary to assign the I/O line to the interrupt function as the
PIO Controller has no effect on inputs and the interrupt lines (FIQ or IRQs) are used only as
inputs.
27.3.3 Power Management
The Power Management Controller controls the PIO Controller clock in order to save power.
Writing any of the registers of the user interface does not require the PIO Controller clock to be
enabled. This means that the configuration of the I/O lines does not require the PIO Controller
clock to be enabled.
However, when the clock is disabled, not all of the features of the PIO Controller are available.
Note that the Input Change Interrupt and the read of the pin level require the clock to be
validated.
After a hardware reset, the PIO clock is disabled by default.
The user must configure the Power Management Controller before any access to the input line
information.
27.3.4 Interrupt Generation
For interrupt handling, the PIO Controllers are considered as user peripherals. This means that
the PIO Controller interrupt lines are connected among the interrupt sources 2 to 31. Refer to the
PIO Controller peripheral identifier in the product description to identify the interrupt sources
dedicated to the PIO Controllers.
The PIO Controller interrupt can be generated only if the PIO Controller clock is enabled.
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27.4 Functional Description
The PIO Controller features up to 32 fully-programmable I/O lines. Most of the control logic asso-
ciated to each I/O is represented in Figure 27-3. In this description each signal shown
represents but one of up to 32 possible indexes.
Figure 27-3. I/O Line Control Logic
1
0
1
0
1
0
Glitch
Filter
Peripheral B
Input
Peripheral A
Input
1
0
PIO_IFDR[0]
PIO_IFSR[0]
PIO_IFER[0]
Edge
Detector
PIO_PDSR[0] PIO_ISR[0]
PIO_IDR[0]
PIO_IMR[0]
PIO_IER[0]
PIO Interrupt
(Up to 32 possible inputs)
PIO_ISR[31]
PIO_IDR[31]
PIO_IMR[31]
PIO_IER[31]
Pad
1
0
PIO_PUDR[0]
PIO_PUSR[0]
PIO_PUER[0]
PIO_MDDR[0]
PIO_MDSR[0]
PIO_MDER[0]
PIO_CODR[0]
PIO_ODSR[0]
PIO_SODR[0]
PIO_PDR[0]
PIO_PSR[0]
PIO_PER[0]
1
0
1
0
PIO_BSR[0]
PIO_ABSR[0]
PIO_ASR[0]
Peripheral B
Output Enable
Peripheral A
Output Enable
Peripheral B
Output
Peripheral A
Output
PIO_ODR[0]
PIO_OSR[0]
PIO_OER[0]
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27.4.1 Pull-up Resistor Control
Each I/O line is designed with an embedded pull-up resistor. The pull-up resistor can be enabled
or disabled by writing respectively PIO_PUER (Pull-up Enable Register) and PIO_PUDR (Pull-
up Disable Resistor). Writing in these registers results in setting or clearing the corresponding bit
in PIO_PUSR (Pull-up Status Register). Reading a 1 in PIO_PUSR means the pull-up is dis-
abled and reading a 0 means the pull-up is enabled.
Control of the pull-up resistor is possible regardless of the configuration of the I/O line.
After reset, all of the pull-ups are enabled, i.e. PIO_PUSR resets at the value 0x0.
27.4.2 I/O Line or Peripheral Function Selection
When a pin is multiplexed with one or two peripheral functions, the selection is controlled with
the registers PIO_PER (PIO Enable Register) and PIO_PDR (PIO Disable Register). The regis-
ter PIO_PSR (PIO Status Register) is the result of the set and clear registers and indicates
whether the pin is controlled by the corresponding peripheral or by the PIO Controller. A value of
0 indicates that the pin is controlled by the corresponding on-chip peripheral selected in the
PIO_ABSR (AB Select Status Register). A value of 1 indicates the pin is controlled by the PIO
controller.
If a pin is used as a general purpose I/O line (not multiplexed with an on-chip peripheral),
PIO_PER and PIO_PDR have no effect and PIO_PSR returns 1 for the corresponding bit.
After reset, most generally, the I/O lines are controlled by the PIO controller, i.e. PIO_PSR
resets at 1. However, in some events, it is important that PIO lines are controlled by the periph-
eral (as in the case of memory chip select lines that must be driven inactive after reset or for
address lines that must be driven low for booting out of an external memory). Thus, the reset
value of PIO_PSR is defined at the product level, depending on the multiplexing of the device.
27.4.3 Peripheral A or B Selection
The PIO Controller provides multiplexing of up to two peripheral functions on a single pin. The
selection is performed by writing PIO_ASR (A Select Register) and PIO_BSR (Select B Regis-
ter). PIO_ABSR (AB Select Status Register) indicates which peripheral line is currently selected.
For each pin, the corresponding bit at level 0 means peripheral A is selected whereas the corre-
sponding bit at level 1 indicates that peripheral B is selected.
Note that multiplexing of peripheral lines A and B only affects the output line. The peripheral
input lines are always connected to the pin input.
After reset, PIO_ABSR is 0, thus indicating that all the PIO lines are configured on peripheral A.
However, peripheral A generally does not drive the pin as the PIO Controller resets in I/O line
mode.
Writing in PIO_ASR and PIO_BSR manages PIO_ABSR regardless of the configuration of the
pin. However, assignment of a pin to a peripheral function requires a write in the corresponding
peripheral selection register (PIO_ASR or PIO_BSR) in addition to a write in PIO_PDR.
27.4.4 Output Control
When the I/0 line is assigned to a peripheral function, i.e. the corresponding bit in PIO_PSR is at
0, the drive of the I/O line is controlled by the peripheral. Peripheral A or B, depending on the
value in PIO_ABSR, determines whether the pin is driven or not.
When the I/O line is controlled by the PIO controller, the pin can be configured to be driven. This
is done by writing PIO_OER (Output Enable Register) and PIO_ODR (Output Disable Register).
The results of these write operations are detected in PIO_OSR (Output Status Register). When
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a bit in this register is at 0, the corresponding I/O line is used as an input only. When the bit is at
1, the corresponding I/O line is driven by the PIO controller.
The level driven on an I/O line can be determined by writing in PIO_SODR (Set Output Data
Register) and PIO_CODR (Clear Output Data Register). These write operations respectively set
and clear PIO_ODSR (Output Data Status Register), which represents the data driven on the I/O
lines. Writing in PIO_OER and PIO_ODR manages PIO_OSR whether the pin is configured to
be controlled by the PIO controller or assigned to a peripheral function. This enables configura-
tion of the I/O line prior to setting it to be managed by the PIO Controller.
Similarly, writing in PIO_SODR and PIO_CODR effects PIO_ODSR. This is important as it
defines the first level driven on the I/O line.
27.4.5 Synchronous Data Output
Controlling all parallel busses using several PIOs requires two successive write operations in the
PIO_SODR and PIO_CODR registers. This may lead to unexpected transient values. The PIO
controller offers a direct control of PIO outputs by single write access to PIO_ODSR (Output
Data Status Register). Only bits unmasked by PIO_OWSR (Output Write Status Register) are
written. The mask bits in the PIO_OWSR are set by writing to PIO_OWER (Output Write Enable
Register) and cleared by writing to PIO_OWDR (Output Write Disable Register).
After reset, the synchronous data output is disabled on all the I/O lines as PIO_OWSR resets at
0x0.
27.4.6 Multi Drive Control (Open Drain)
Each I/O can be independently programmed in Open Drain by using the Multi Drive feature. This
feature permits several drivers to be connected on the I/O line which is driven low only by each
device. An external pull-up resistor (or enabling of the internal one) is generally required to guar-
antee a high level on the line.
The Multi Drive feature is controlled by PIO_MDER (Multi-driver Enable Register) and
PIO_MDDR (Multi-driver Disable Register). The Multi Drive can be selected whether the I/O line
is controlled by the PIO controller or assigned to a peripheral function. PIO_MDSR (Multi-driver
Status Register) indicates the pins that are configured to support external drivers.
After reset, the Multi Drive feature is disabled on all pins, i.e. PIO_MDSR resets at value 0x0.
27.4.7 Output Line Timings
Figure 27-4 shows how the outputs are driven either by writing PIO_SODR or PIO_CODR, or by
directly writing PIO_ODSR. This last case is valid only if the corresponding bit in PIO_OWSR is
set. Figure 27-4 also shows when the feedback in PIO_PDSR is available.
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Figure 27-4. Output Line Timings
27.4.8 Inputs
The level on each I/O line can be read through PIO_PDSR (Pin Data Status Register). This reg-
ister indicates the level of the I/O lines regardless of their configuration, whether uniquely as an
input or driven by the PIO controller or driven by a peripheral.
Reading the I/O line levels requires the clock of the PIO controller to be enabled, otherwise
PIO_PDSR reads the levels present on the I/O line at the time the clock was disabled.
27.4.9 Input Glitch Filtering
Optional input glitch filters are independently programmable on each I/O line. When the glitch fil-
ter is enabled, a glitch with a duration of less than 1/2 Master Clock (MCK) cycle is automatically
rejected, while a pulse with a duration of 1 Master Clock cycle or more is accepted. For pulse
durations between 1/2 Master Clock cycle and 1 Master Clock cycle the pulse may or may not
be taken into account, depending on the precise timing of its occurrence. Thus for a pulse to be
visible it must exceed 1 Master Clock cycle, whereas for a glitch to be reliably filtered out, its
duration must not exceed 1/2 Master Clock cycle. The filter introduces one Master Clock cycle
latency if the pin level change occurs before a rising edge. However, this latency does not
appear if the pin level change occurs before a falling edge. This is illustrated in Figure 27-5.
The glitch filters are controlled by the register set; PIO_IFER (Input Filter Enable Register),
PIO_IFDR (Input Filter Disable Register) and PIO_IFSR (Input Filter Status Register). Writing
PIO_IFER and PIO_IFDR respectively sets and clears bits in PIO_IFSR. This last register
enables the glitch filter on the I/O lines.
When the glitch filter is enabled, it does not modify the behavior of the inputs on the peripherals.
It acts only on the value read in PIO_PDSR and on the input change interrupt detection. The
glitch filters require that the PIO Controller clock is enabled.
2 cycles
APB Access
2 cycles
APB Access
MCK
Write PIO_SODR
Write PIO_ODSR at 1
PIO_ODSR
PIO_PDSR
Write PIO_CODR
Write PIO_ODSR at 0
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Figure 27-5. Input Glitch Filter Timing
27.4.10 Input Change Interrupt
The PIO Controller can be programmed to generate an interrupt when it detects an input change
on an I/O line. The Input Change Interrupt is controlled by writing PIO_IER (Interrupt Enable
Register) and PIO_IDR (Interrupt Disable Register), which respectively enable and disable the
input change interrupt by setting and clearing the corresponding bit in PIO_IMR (Interrupt Mask
Register). As Input change detection is possible only by comparing two successive samplings of
the input of the I/O line, the PIO Controller clock must be enabled. The Input Change Interrupt is
available, regardless of the configuration of the I/O line, i.e. configured as an input only, con-
trolled by the PIO Controller or assigned to a peripheral function.
When an input change is detected on an I/O line, the corresponding bit in PIO_ISR (Interrupt
Status Register) is set. If the corresponding bit in PIO_IMR is set, the PIO Controller interrupt
line is asserted. The interrupt signals of the thirty-two channels are ORed-wired together to gen-
erate a single interrupt signal to the Advanced Interrupt Controller.
When the software reads PIO_ISR, all the interrupts are automatically cleared. This signifies that
all the interrupts that are pending when PIO_ISR is read must be handled.
Figure 27-6. Input Change Interrupt Timings
27.5 I/O Lines Programming Example
The programing example as shown in Table 27-1 below is used to define the following
configuration.
• 4-bit output port on I/O lines 0 to 3, (should be written in a single write operation), open-drain,
with pull-up resistor
MCK
Pin Level
PIO_PDSR
if PIO_IFSR = 0
PIO_PDSR
if PIO_IFSR = 1
1 cycle 1 cycle 1 cycle
up to 1.5 cycles
2 cycles
up to 2.5 cycles up to 2 cycles
1 cycle
1 cycle
MCK
Pin Level
Read PIO_ISR APB Access
PIO_ISR
APB Access
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• Four output signals on I/O lines 4 to 7 (to drive LEDs for example), driven high and low, no
pull-up resistor
• Four input signals on I/O lines 8 to 11 (to read push-button states for example), with pull-up
resistors, glitch filters and input change interrupts
• Four input signals on I/O line 12 to 15 to read an external device status (polled, thus no input
change interrupt), no pull-up resistor, no glitch filter
• I/O lines 16 to 19 assigned to peripheral A functions with pull-up resistor
• I/O lines 20 to 23 assigned to peripheral B functions, no pull-up resistor
• I/O line 24 to 27 assigned to peripheral A with Input Change Interrupt and pull-up resistor
Table 27-1. Programming Example
Register Value to be Written
PIO_PER 0x0000 FFFF
PIO_PDR 0x0FFF 0000
PIO_OER 0x0000 00FF
PIO_ODR 0x0FFF FF00
PIO_IFER 0x0000 0F00
PIO_IFDR 0x0FFF F0FF
PIO_SODR 0x0000 0000
PIO_CODR 0x0FFF FFFF
PIO_IER 0x0F00 0F00
PIO_IDR 0x00FF F0FF
PIO_MDER 0x0000 000F
PIO_MDDR 0x0FFF FFF0
PIO_PUDR 0x00F0 00F0
PIO_PUER 0x0F0F FF0F
PIO_ASR 0x0F0F 0000
PIO_BSR 0x00F0 0000
PIO_OWER 0x0000 000F
PIO_OWDR 0x0FFF FFF0
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27.6 Programmable Multibit ECC Error Location (PIO) User Interface
Each I/O line controlled by the PIO Controller is associated with a bit in each of the PIO Control-
ler User Interface registers. Each register is 32 bits wide. If a parallel I/O line is not defined,
writing to the corresponding bits has no effect. Undefined bits read zero. If the I/O line is not mul-
tiplexed with any peripheral, the I/O line is controlled by the PIO Controller and PIO_PSR returns
1 systematically.
Table 27-2. Register Mapping
Offset Register Name Access Reset
0x0000 PIO Enable Register PIO_PER Write-only –
0x0004 PIO Disable Register PIO_PDR Write-only –
0x0008 PIO Status Register PIO_PSR Read-only (1)
0x000C Reserved
0x0010 Output Enable Register PIO_OER Write-only –
0x0014 Output Disable Register PIO_ODR Write-only –
0x0018 Output Status Register PIO_OSR Read-only 0x0000 0000
0x001C Reserved
0x0020 Glitch Input Filter Enable Register PIO_IFER Write-only –
0x0024 Glitch Input Filter Disable Register PIO_IFDR Write-only –
0x0028 Glitch Input Filter Status Register PIO_IFSR Read-only 0x0000 0000
0x002C Reserved
0x0030 Set Output Data Register PIO_SODR Write-only –
0x0034 Clear Output Data Register PIO_CODR Write-only
0x0038 Output Data Status Register PIO_ODSR
Read-only
or(2)
Read-write
–
0x003C Pin Data Status Register PIO_PDSR Read-only (3)
0x0040 Interrupt Enable Register PIO_IER Write-only –
0x0044 Interrupt Disable Register PIO_IDR Write-only –
0x0048 Interrupt Mask Register PIO_IMR Read-only 0x00000000
0x004C Interrupt Status Register(4) PIO_ISR Read-only 0x00000000
0x0050 Multi-driver Enable Register PIO_MDER Write-only –
0x0054 Multi-driver Disable Register PIO_MDDR Write-only –
0x0058 Multi-driver Status Register PIO_MDSR Read-only 0x00000000
0x005C Reserved
0x0060 Pull-up Disable Register PIO_PUDR Write-only –
0x0064 Pull-up Enable Register PIO_PUER Write-only –
0x0068 Pad Pull-up Status Register PIO_PUSR Read-only 0x00000000
0x006C Reserved
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Notes: 1. Reset value of PIO_PSR depends on the product implementation.
2. PIO_ODSR is Read-only or Read/Write depending on PIO_OWSR I/O lines.
3. Reset value of PIO_PDSR depends on the level of the I/O lines. Reading the I/O line levels requires the clock of the PIO
Controller to be enabled, otherwise PIO_PDSR reads the levels present on the I/O line at the time the clock was disabled.
4. PIO_ISR is reset at 0x0. However, the first read of the register may read a different value as input changes may have
occurred.
5. Only this set of registers clears the status by writing 1 in the first register and sets the status by writing 1 in the second
register.
0x0070 Peripheral A Select Register(5) PIO_ASR Write-only –
0x0074 Peripheral B Select Register(5) PIO_BSR Write-only –
0x0078 AB Status Register(5) PIO_ABSR Read-only 0x00000000
0x007C
to
0x009C
Reserved
0x00A0 Output Write Enable PIO_OWER Write-only –
0x00A4 Output Write Disable PIO_OWDR Write-only –
0x00A8 Output Write Status Register PIO_OWSR Read-only 0x00000000
0x00AC Reserved
Table 27-2. Register Mapping (Continued)
Offset Register Name Access Reset
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27.6.1 PIO Controller PIO Enable Register
Name: PIO_PER
Access Type: Write-only
• P0-P31: PIO Enable
0 = No effect.
1 = Enables the PIO to control the corresponding pin (disables peripheral control of the pin).
27.6.2 PIO Controller PIO Disable Register
Name: PIO_PDR
Access Type: Write-only
• P0-P31: PIO Disable
0 = No effect.
1 = Disables the PIO from controlling the corresponding pin (enables peripheral control of the pin).
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
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27.6.3 PIO Controller PIO Status Register
Name: PIO_PSR
Access Type: Read-only
• P0-P31: PIO Status
0 = PIO is inactive on the corresponding I/O line (peripheral is active).
1 = PIO is active on the corresponding I/O line (peripheral is inactive).
27.6.4 PIO Controller Output Enable Register
Name: PIO_OER
Access Type: Write-only
• P0-P31: Output Enable
0 = No effect.
1 = Enables the output on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
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27.6.5 PIO Controller Output Disable Register
Name: PIO_ODR
Access Type: Write-only
• P0-P31: Output Disable
0 = No effect.
1 = Disables the output on the I/O line.
27.6.6 PIO Controller Output Status Register
Name: PIO_OSR
Access Type: Read-only
• P0-P31: Output Status
0 = The I/O line is a pure input.
1 = The I/O line is enabled in output.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
253
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6175M–ATARM–26-Oct-12
27.6.7 PIO Controller Input Filter Enable Register
Name: PIO_IFER
Access Type: Write-only
• P0-P31: Input Filter Enable
0 = No effect.
1 = Enables the input glitch filter on the I/O line.
27.6.8 PIO Controller Input Filter Disable Register
Name: PIO_IFDR
Access Type: Write-only
• P0-P31: Input Filter Disable
0 = No effect.
1 = Disables the input glitch filter on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
254
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.9 PIO Controller Input Filter Status Register
Name: PIO_IFSR
Access Type: Read-only
• P0-P31: Input Filer Status
0 = The input glitch filter is disabled on the I/O line.
1 = The input glitch filter is enabled on the I/O line.
27.6.10 PIO Controller Set Output Data Register
Name: PIO_SODR
Access Type: Write-only
• P0-P31: Set Output Data
0 = No effect.
1 = Sets the data to be driven on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
255
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.11 PIO Controller Clear Output Data Register
Name: PIO_CODR
Access Type: Write-only
• P0-P31: Set Output Data
0 = No effect.
1 = Clears the data to be driven on the I/O line.
27.6.12 PIO Controller Output Data Status Register
Name: PIO_ODSR
Access Type: Read-only or Read-write
• P0-P31: Output Data Status
0 = The data to be driven on the I/O line is 0.
1 = The data to be driven on the I/O line is 1.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
256
SAM7S Series [DATASHEET]
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27.6.13 PIO Controller Pin Data Status Register
Name: PIO_PDSR
Access Type: Read-only
• P0-P31: Output Data Status
0 = The I/O line is at level 0.
1 = The I/O line is at level 1.
27.6.14 PIO Controller Interrupt Enable Register
Name: PIO_IER
Access Type: Write-only
• P0-P31: Input Change Interrupt Enable
0 = No effect.
1 = Enables the Input Change Interrupt on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
257
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.15 PIO Controller Interrupt Disable Register
Name: PIO_IDR
Access Type: Write-only
• P0-P31: Input Change Interrupt Disable
0 = No effect.
1 = Disables the Input Change Interrupt on the I/O line.
27.6.16 PIO Controller Interrupt Mask Register
Name: PIO_IMR
Access Type: Read-only
• P0-P31: Input Change Interrupt Mask
0 = Input Change Interrupt is disabled on the I/O line.
1 = Input Change Interrupt is enabled on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
258
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.17 PIO Controller Interrupt Status Register
Name: PIO_ISR
Access Type: Read-only
• P0-P31: Input Change Interrupt Status
0 = No Input Change has been detected on the I/O line since PIO_ISR was last read or since reset.
1 = At least one Input Change has been detected on the I/O line since PIO_ISR was last read or since reset.
27.6.18 PIO Multi-driver Enable Register
Name: PIO_MDER
Access Type: Write-only
• P0-P31: Multi Drive Enable.
0 = No effect.
1 = Enables Multi Drive on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
259
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.19 PIO Multi-driver Disable Register
Name: PIO_MDDR
Access Type: Write-only
• P0-P31: Multi Drive Disable.
0 = No effect.
1 = Disables Multi Drive on the I/O line.
27.6.20 PIO Multi-driver Status Register
Name: PIO_MDSR
Access Type: Read-only
• P0-P31: Multi Drive Status.
0 = The Multi Drive is disabled on the I/O line. The pin is driven at high and low level.
1 = The Multi Drive is enabled on the I/O line. The pin is driven at low level only.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
260
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
27.6.21 PIO Pull Up Disable Register
Name: PIO_PUDR
Access Type: Write-only
• P0-P31: Pull Up Disable.
0 = No effect.
1 = Disables the pull up resistor on the I/O line.
27.6.22 PIO Pull Up Enable Register
Name: PIO_PUER
Access Type: Write-only
• P0-P31: Pull Up Enable.
0 = No effect.
1 = Enables the pull up resistor on the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
261
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27.6.23 PIO Pull Up Status Register
Name: PIO_PUSR
Access Type: Read-only
• P0-P31: Pull Up Status.
0 = Pull Up resistor is enabled on the I/O line.
1 = Pull Up resistor is disabled on the I/O line.
27.6.24 PIO Peripheral A Select Register
Name: PIO_ASR
Access Type: Write-only
• P0-P31: Peripheral A Select.
0 = No effect.
1 = Assigns the I/O line to the Peripheral A function.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
262
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6175M–ATARM–26-Oct-12
27.6.25 PIO Peripheral B Select Register
Name: PIO_BSR
Access Type: Write-only
• P0-P31: Peripheral B Select.
0 = No effect.
1 = Assigns the I/O line to the peripheral B function.
27.6.26 PIO Peripheral A B Status Register
Name: PIO_ABSR
Access Type: Read-only
• P0-P31: Peripheral A B Status.
0 = The I/O line is assigned to the Peripheral A.
1 = The I/O line is assigned to the Peripheral B.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
263
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6175M–ATARM–26-Oct-12
27.6.27 PIO Output Write Enable Register
Name: PIO_OWER
Access Type: Write-only
• P0-P31: Output Write Enable.
0 = No effect.
1 = Enables writing PIO_ODSR for the I/O line.
27.6.28 PIO Output Write Disable Register
Name: PIO_OWDR
Access Type: Write-only
• P0-P31: Output Write Disable.
0 = No effect.
1 = Disables writing PIO_ODSR for the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
264
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6175M–ATARM–26-Oct-12
27.6.29 PIO Output Write Status Register
Name: PIO_OWSR
Access Type: Read-only
• P0-P31: Output Write Status.
0 = Writing PIO_ODSR does not affect the I/O line.
1 = Writing PIO_ODSR affects the I/O line.
31 30 29 28 27 26 25 24
P31 P30 P29 P28 P27 P26 P25 P24
23 22 21 20 19 18 17 16
P23 P22 P21 P20 P19 P18 P17 P16
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
76543210
P7 P6 P5 P4 P3 P2 P1 P0
265
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266
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267
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268
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269
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28. Serial Peripheral Interface (SPI)
28.1 Overview
The Serial Peripheral Interface (SPI) circuit is a synchronous serial data link that provides communication with
external devices in Master or Slave Mode. It also enables communication between processors if an external pro-
cessor is connected to the system.
The Serial Peripheral Interface is essentially a shift register that serially transmits data bits to other SPIs. During a
data transfer, one SPI system acts as the “master”' which controls the data flow, while the other devices act as
“slaves'' which have data shifted into and out by the master. Different CPUs can take turn being masters (Multiple
Master Protocol opposite to Single Master Protocol where one CPU is always the master while all of the others are
always slaves) and one master may simultaneously shift data into multiple slaves. However, only one slave may
drive its output to write data back to the master at any given time.
A slave device is selected when the master asserts its NSS signal. If multiple slave devices exist, the master gen-
erates a separate slave select signal for each slave (NPCS).
The SPI system consists of two data lines and two control lines:
• Master Out Slave In (MOSI): This data line supplies the output data from the master shifted into the input(s) of
the slave(s).
• Master In Slave Out (MISO): This data line supplies the output data from a slave to the input of the master.
There may be no more than one slave transmitting data during any particular transfer.
• Serial Clock (SPCK): This control line is driven by the master and regulates the flow of the data bits. The master
may transmit data at a variety of baud rates; the SPCK line cycles once for each bit that is transmitted.
• Slave Select (NSS): This control line allows slaves to be turned on and off by hardware.
28.2 Block Diagram
Figure 28-1. Block Diagram
SPI Interface
Interrupt Control
PIO
PDC
PMC MCK
SPI Interrupt
SPCK
MISO
MOSI
NPCS0/NSS
NPCS1
NPCS2
NPCS3
APB
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28.3 Application Block Diagram
Figure 28-2. Application Block Diagram: Single Master/Multiple Slave Implementation
28.4 Signal Description
28.5 Product Dependencies
28.5.1 I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines. The programmer
must first program the PIO controllers to assign the SPI pins to their peripheral functions.
28.5.2 Power Management
The SPI may be clocked through the Power Management Controller (PMC), thus the programmer must first config-
ure the PMC to enable the SPI clock.
28.5.3 Interrupt
The SPI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling the SPI
interrupt requires programming the AIC before configuring the SPI.
SPI Master
SPCK
MISO
MOSI
NPCS0
NPCS1
NPCS2
SPCK
MISO
MOSI
NSS
Slave 0
SPCK
MISO
MOSI
NSS
Slave 1
SPCK
MISO
MOSI
NSS
Slave 2
NC
NPCS3
Table 28-1. Signal Description
Pin Name Pin Description
Type
Master Slave
MISO Master In Slave Out Input Output
MOSI Master Out Slave In Output Input
SPCK Serial Clock Output Input
NPCS1-NPCS3 Peripheral Chip Selects Output Unused
NPCS0/NSS Peripheral Chip Select/Slave Select Output Input
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28.6 Functional Description
28.6.1 Modes of Operation
The SPI operates in Master Mode or in Slave Mode.
Operation in Master Mode is programmed by writing at 1 the MSTR bit in the Mode Register. The pins NPCS0 to
NPCS3 are all configured as outputs, the SPCK pin is driven, the MISO line is wired on the receiver input and the
MOSI line driven as an output by the transmitter.
If the MSTR bit is written at 0, the SPI operates in Slave Mode. The MISO line is driven by the transmitter output,
the MOSI line is wired on the receiver input, the SPCK pin is driven by the transmitter to synchronize the receiver.
The NPCS0 pin becomes an input, and is used as a Slave Select signal (NSS). The pins NPCS1 to NPCS3 are not
driven and can be used for other purposes.
The data transfers are identically programmable for both modes of operations. The baud rate generator is activated
only in Master Mode.
28.6.2 Data Transfer
Four combinations of polarity and phase are available for data transfers. The clock polarity is programmed with the
CPOL bit in the Chip Select Register. The clock phase is programmed with the NCPHA bit. These two parameters
determine the edges of the clock signal on which data is driven and sampled. Each of the two parameters has two
possible states, resulting in four possible combinations that are incompatible with one another. Thus, a mas-
ter/slave pair must use the same parameter pair values to communicate. If multiple slaves are used and fixed in
different configurations, the master must reconfigure itself each time it needs to communicate with a different slave.
Table 28-2 shows the four modes and corresponding parameter settings.
Figure 28-3 and Figure 28-4 show examples of data transfers.
Table 28-2. SPI Bus Protocol Mode
SPI Mode CPOL NCPHA
001
100
211
310
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SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 28-3. SPI Transfer Format (NCPHA = 1, 8 bits per transfer)
Figure 28-4. SPI Transfer Format (NCPHA = 0, 8 bits per transfer)
6
*
SPCK
(CPOL = 0)
SPCK
(CPOL = 1)
MOSI
(from master)
MISO
(from slave)
NSS
(to slave)
SPCK cycle (for reference)
MSB
MSB
LSB
LSB
6
6
5
5
4
4
3
3
2
2
1
1
* Not defined, but normally MSB of previous character received.
1 2345 786
*
SPCK
(CPOL = 0)
SPCK
(CPOL = 1)
1 2345 7
MOSI
(from master)
MISO
(from slave)
NSS
(to slave)
SPCK cycle (for reference) 8
MSB
MSB
LSB
LSB
6
6
5
5
4
4
3
3
1
1
* Not defined but normally LSB of previous character transmitted.
2
2
6
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28.6.3 Master Mode Operations
When configured in Master Mode, the SPI operates on the clock generated by the internal programmable baud
rate generator. It fully controls the data transfers to and from the slave(s) connected to the SPI bus. The SPI drives
the chip select line to the slave and the serial clock signal (SPCK).
The SPI features two holding registers, the Transmit Data Register and the Receive Data Register, and a single
Shift Register. The holding registers maintain the data flow at a constant rate.
After enabling the SPI, a data transfer begins when the processor writes to the SPI_TDR (Transmit Data Register).
The written data is immediately transferred in the Shift Register and transfer on the SPI bus starts. While the data
in the Shift Register is shifted on the MOSI line, the MISO line is sampled and shifted in the Shift Register. Trans-
mission cannot occur without reception.
Before writing the TDR, the PCS field must be set in order to select a slave.
If new data is written in SPI_TDR during the transfer, it stays in it until the current transfer is completed. Then, the
received data is transferred from the Shift Register to SPI_RDR, the data in SPI_TDR is loaded in the Shift Regis-
ter and a new transfer starts.
The transfer of a data written in SPI_TDR in the Shift Register is indicated by the TDRE bit (Transmit Data Register
Empty) in the Status Register (SPI_SR). When new data is written in SPI_TDR, this bit is cleared. The TDRE bit is
used to trigger the Transmit PDC channel.
The end of transfer is indicated by the TXEMPTY flag in the SPI_SR register. If a transfer delay (DLYBCT) is
greater than 0 for the last transfer, TXEMPTY is set after the completion of said delay. The master clock (MCK) can
be switched off at this time.
The transfer of received data from the Shift Register in SPI_RDR is indicated by the RDRF bit (Receive Data Reg-
ister Full) in the Status Register (SPI_SR). When the received data is read, the RDRF bit is cleared.
If the SPI_RDR (Receive Data Register) has not been read before new data is received, the Overrun Error bit
(OVRES) in SPI_SR is set. As long as this flag is set, data is loaded in SPI_RDR. The user has to read the status
register to clear the OVRES bit.
Figure 28-5 on page 275 shows a block diagram of the SPI when operating in Master Mode. Figure 28-6 on page
276 shows a flow chart describing how transfers are handled.
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SAM7S Series [DATASHEET]
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28.6.3.1 Master Mode Block Diagram
Figure 28-5. Master Mode Block Diagram
Shift Register
SPCK
MOSI
LSB MSB
MISO
SPI_RDR
RD
SPI
Clock
TDRE
SPI_TDR
TD
RDRF
OVRES
SPI_CSR0..3
CPOL
NCPHA
BITS
MCK Baud Rate Generator
SPI_CSR0..3
SCBR
NPCS3
NPCS0
NPCS2
NPCS1
NPCS0
0
1
PS
SPI_MR
PCS
SPI_TDR
PCS
MODF
Current
Peripheral
SPI_RDR
PCS
SPI_CSR0..3
CSAAT
PCSDEC
MODFDIS
MSTR
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28.6.3.2 Master Mode Flow Diagram
Figure 28-6. Master Mode Flow Diagram S
28.6.3.3 Clock Generation
The SPI Baud rate clock is generated by dividing the Master Clock (MCK), by a value between 1 and 255.
SPI Enable
CSAAT ?
PS ?
1
0
0
1
1
NPCS = SPI_TDR(PCS) NPCS = SPI_MR(PCS)
Delay DLYBS
Serializer = SPI_TDR(TD)
TDRE = 1
Data Transfer
SPI_RDR(RD) = Serializer
RDRF = 1
TDRE ?
NPCS = 0xF
Delay DLYBCS
Fixed
peripheral
Variable
peripheral
Delay DLYBCT
0
1
CSAAT ?
0
TDRE ?
1
0
PS ?
0
1
SPI_TDR(PCS)
= NPCS ?
no
yes SPI_MR(PCS)
= NPCS ?
no
NPCS = 0xF
Delay DLYBCS
NPCS = SPI_TDR(PCS)
NPCS = 0xF
Delay DLYBCS
NPCS = SPI_MR(PCS),
SPI_TDR(PCS)
Fixed
peripheral
Variable
peripheral
- NPCS defines the current Chip Select
- CSAAT, DLYBS, DLYBCT refer to the fields of the
Chip Select Register corresponding to the Current Chip Select
- When NPCS is 0xF, CSAAT is 0.
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This allows a maximum operating baud rate at up to Master Clock and a minimum operating baud rate of MCK
divided by 255.
Programming the SCBR field at 0 is forbidden. Triggering a transfer while SCBR is at 0 can lead to unpredictable
results.
At reset, SCBR is 0 and the user has to program it at a valid value before performing the first transfer.
The divisor can be defined independently for each chip select, as it has to be programmed in the SCBR field of the
Chip Select Registers. This allows the SPI to automatically adapt the baud rate for each interfaced peripheral with-
out reprogramming.
28.6.3.4 Transfer Delays
Figure 28-7 shows a chip select transfer change and consecutive transfers on the same chip select. Three delays
can be programmed to modify the transfer waveforms:
• The delay between chip selects, programmable only once for all the chip selects by writing the DLYBCS field in
the Mode Register. Allows insertion of a delay between release of one chip select and before assertion of a new
one.
• The delay before SPCK, independently programmable for each chip select by writing the field DLYBS. Allows
the start of SPCK to be delayed after the chip select has been asserted.
• The delay between consecutive transfers, independently programmable for each chip select by writing the
DLYBCT field. Allows insertion of a delay between two transfers occurring on the same chip select
These delays allow the SPI to be adapted to the interfaced peripherals and their speed and bus release time.
Figure 28-7. Programmable Delays
28.6.3.5 Peripheral Selection
The serial peripherals are selected through the assertion of the NPCS0 to NPCS3 signals. By default, all the NPCS
signals are high before and after each transfer.
The peripheral selection can be performed in two different ways:
• Fixed Peripheral Select: SPI exchanges data with only one peripheral
• Variable Peripheral Select: Data can be exchanged with more than one peripheral
Fixed Peripheral Select is activated by writing the PS bit to zero in SPI_MR (Mode Register). In this case, the cur-
rent peripheral is defined by the PCS field in SPI_MR and the PCS field in the SPI_TDR has no effect.
Variable Peripheral Select is activated by setting PS bit to one. The PCS field in SPI_TDR is used to select the cur-
rent peripheral. This means that the peripheral selection can be defined for each new data.
DLYBCS DLYBS DLYBCT DLYBCT
Chip Select 1
Chip Select 2
SPCK
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The Fixed Peripheral Selection allows buffer transfers with a single peripheral. Using the PDC is an optimal means,
as the size of the data transfer between the memory and the SPI is either 8 bits or 16 bits. However, changing the
peripheral selection requires the Mode Register to be reprogrammed.
The Variable Peripheral Selection allows buffer transfers with multiple peripherals without reprogramming the
Mode Register. Data written in SPI_TDR is 32 bits wide and defines the real data to be transmitted and the periph-
eral it is destined to. Using the PDC in this mode requires 32-bit wide buffers, with the data in the LSBs and the
PCS and LASTXFER fields in the MSBs, however the SPI still controls the number of bits (8 to16) to be transferred
through MISO and MOSI lines with the chip select configuration registers. This is not the optimal means in term of
memory size for the buffers, but it provides a very effective means to exchange data with several peripherals with-
out any intervention of the processor.
28.6.3.6 Peripheral Chip Select Decoding
The user can program the SPI to operate with up to 15 peripherals by decoding the four Chip Select lines, NPCS0
to NPCS3 with an external logic. This can be enabled by writing the PCSDEC bit at 1 in the Mode Register
(SPI_MR).
When operating without decoding, the SPI makes sure that in any case only one chip select line is activated, i.e.
driven low at a time. If two bits are defined low in a PCS field, only the lowest numbered chip select is driven low.
When operating with decoding, the SPI directly outputs the value defined by the PCS field of either the Mode Reg-
ister or the Transmit Data Register (depending on PS).
As the SPI sets a default value of 0xF on the chip select lines (i.e. all chip select lines at 1) when not processing
any transfer, only 15 peripherals can be decoded.
The SPI has only four Chip Select Registers, not 15. As a result, when decoding is activated, each chip select
defines the characteristics of up to four peripherals. As an example, SPI_CRS0 defines the characteristics of the
externally decoded peripherals 0 to 3, corresponding to the PCS values 0x0 to 0x3. Thus, the user has to make
sure to connect compatible peripherals on the decoded chip select lines 0 to 3, 4 to 7, 8 to 11 and 12 to 14.
28.6.3.7 Peripheral Deselection
When operating normally, as soon as the transfer of the last data written in SPI_TDR is completed, the NPCS lines
all rise. This might lead to runtime error if the processor is too long in responding to an interrupt, and thus might
lead to difficulties for interfacing with some serial peripherals requiring the chip select line to remain active during a
full set of transfers.
To facilitate interfacing with such devices, the Chip Select Register can be programmed with the CSAAT bit (Chip
Select Active After Transfer) at 1. This allows the chip select lines to remain in their current state (low = active) until
transfer to another peripheral is required.
Figure 28-8 shows different peripheral deselection cases and the effect of the CSAAT bit.
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Figure 28-8. Peripheral Deselection
28.6.3.8 Mode Fault Detection
A mode fault is detected when the SPI is programmed in Master Mode and a low level is driven by an external mas-
ter on the NPCS0/NSS signal. NPCS0, MOSI, MISO and SPCK must be configured in open drain through the PIO
controller, so that external pull up resistors are needed to guarantee high level.
When a mode fault is detected, the MODF bit in the SPI_SR is set until the SPI_SR is read and the SPI is automat-
ically disabled until re-enabled by writing the SPIEN bit in the SPI_CR (Control Register) at 1.
By default, the Mode Fault detection circuitry is enabled. The user can disable Mode Fault detection by setting the
MODFDIS bit in the SPI Mode Register (SPI_MR).
28.6.4 SPI Slave Mode
When operating in Slave Mode, the SPI processes data bits on the clock provided on the SPI clock pin (SPCK).
The SPI waits for NSS to go active before receiving the serial clock from an external master. When NSS falls, the
clock is validated on the serializer, which processes the number of bits defined by the BITS field of the Chip Select
Register 0 (SPI_CSR0). These bits are processed following a phase and a polarity defined respectively by the
NCPHA and CPOL bits of the SPI_CSR0. Note that BITS, CPOL and NCPHA of the other Chip Select Registers
have no effect when the SPI is programmed in Slave Mode.
The bits are shifted out on the MISO line and sampled on the MOSI line.
A
NPCS[0..3]
Write SPI_TDR
TDRE
NPCS[0..3]
Write SPI_TDR
TDRE
NPCS[0..3]
Write SPI_TDR
TDRE
DLYBCS
PCS = A
DLYBCS
DLYBCT
A
PCS = B
B
DLYBCS
PCS = A
DLYBCS
DLYBCT
A
PCS = B
B
DLYBCS
DLYBCT
PCS=A
A
DLYBCS
DLYBCT
A
PCS = A
AA
DLYBCT
AA
CSAAT = 0
DLYBCT
AA
CSAAT = 1
A
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When all the bits are processed, the received data is transferred in the Receive Data Register and the RDRF bit
rises. If the SPI_RDR (Receive Data Register) has not been read before new data is received, the Overrun Error
bit (OVRES) in SPI_SR is set. As long as this flag is set, data is loaded in SPI_RDR. The user has to read the sta-
tus register to clear the OVRES bit.
When a transfer starts, the data shifted out is the data present in the Shift Register. If no data has been written in
the Transmit Data Register (SPI_TDR), the last data received is transferred. If no data has been received since the
last reset, all bits are transmitted low, as the Shift Register resets at 0.
When a first data is written in SPI_TDR, it is transferred immediately in the Shift Register and the TDRE bit rises. If
new data is written, it remains in SPI_TDR until a transfer occurs, i.e. NSS falls and there is a valid clock on the
SPCK pin. When the transfer occurs, the last data written in SPI_TDR is transferred in the Shift Register and the
TDRE bit rises. This enables frequent updates of critical variables with single transfers.
Then, a new data is loaded in the Shift Register from the Transmit Data Register. In case no character is ready to
be transmitted, i.e. no character has been written in SPI_TDR since the last load from SPI_TDR to the Shift Regis-
ter, the Shift Register is not modified and the last received character is retransmitted.
Figure 28-9 shows a block diagram of the SPI when operating in Slave Mode.
Figure 28-9. Slave Mode Functional Block Diagram
Shift Register
SPCK
SPIENS
LSB MSB
NSS
MOSI
SPI_RDR
RD
SPI
Clock
TDRE
SPI_TDR
TD
RDRF
OVRES
SPI_CSR0
CPOL
NCPHA
BITS
SPIEN
SPIDIS
MISO
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28.7 Serial Peripheral Interface (SPI) User Interface User Interface
Table 28-3. Register Mapping
Offset Register Name Access Reset
0x00 Control Register SPI_CR Write-only ---
0x04 Mode Register SPI_MR Read-write 0x0
0x08 Receive Data Register SPI_RDR Read-only 0x0
0x0C Transmit Data Register SPI_TDR Write-only ---
0x10 Status Register SPI_SR Read-only 0x000000F0
0x14 Interrupt Enable Register SPI_IER Write-only ---
0x18 Interrupt Disable Register SPI_IDR Write-only ---
0x1C Interrupt Mask Register SPI_IMR Read-only 0x0
0x20 - 0x2C Reserved
0x30 Chip Select Register 0 SPI_CSR0 Read-write 0x0
0x34 Chip Select Register 1 SPI_CSR1 Read-write 0x0
0x38 Chip Select Register 2 SPI_CSR2 Read-write 0x0
0x3C Chip Select Register 3 SPI_CSR3 Read-write 0x0
0x004C - 0x00F8 Reserved – – –
0x004C - 0x00FC Reserved – – –
0x100 - 0x124 Reserved for the PDC
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28.7.1 SPI Control Register
Name: SPI_CR
Access Type: Write-only
• SPIEN: SPI Enable
0 = No effect.
1 = Enables the SPI to transfer and receive data.
• SPIDIS: SPI Disable
0 = No effect.
1 = Disables the SPI.
As soon as SPIDIS is set, SPI finishes its transfer.
All pins are set in input mode and no data is received or transmitted.
If a transfer is in progress, the transfer is finished before the SPI is disabled.
If both SPIEN and SPIDIS are equal to one when the control register is written, the SPI is disabled.
• SWRST: SPI Software Reset
0 = No effect.
1 = Reset the SPI. A software-triggered hardware reset of the SPI interface is performed.
The SPI is in slave mode after software reset.
PDC channels are not affected by software reset.
• LASTXFER: Last Transfer
0 = No effect.
1 = The current NPCS will be deasserted after the character written in TD has been transferred. When CSAAT is set, this
allows to close the communication with the current serial peripheral by raising the corresponding NPCS line as soon as TD
transfer has completed.
31 30 29 28 27 26 25 24
–––––––LASTXFER
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
SWRST–––––SPIDISSPIEN
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28.7.2 SPI Mode Register
Name: SPI_MR
Access Type: Read-write
• MSTR: Master/Slave Mode
0 = SPI is in Slave mode.
1 = SPI is in Master mode.
• PS: Peripheral Select
0 = Fixed Peripheral Select.
1 = Variable Peripheral Select.
• PCSDEC: Chip Select Decode
0 = The chip selects are directly connected to a peripheral device.
1 = The four chip select lines are connected to a 4- to 16-bit decoder.
When PCSDEC equals one, up to 15 Chip Select signals can be generated with the four lines using an external 4- to 16-bit
decoder. The Chip Select Registers define the characteristics of the 15 chip selects according to the following rules:
SPI_CSR0 defines peripheral chip select signals 0 to 3.
SPI_CSR1 defines peripheral chip select signals 4 to 7.
SPI_CSR2 defines peripheral chip select signals 8 to 11.
SPI_CSR3 defines peripheral chip select signals 12 to 14.
• MODFDIS: Mode Fault Detection
0 = Mode fault detection is enabled.
1 = Mode fault detection is disabled.
• LLB: Local Loopback Enable
0 = Local loopback path disabled.
1 = Local loopback path enabled.
LLB controls the local loopback on the data serializer for testing in Master Mode only. (MISO is internally connected on
MOSI.)
• PCS: Peripheral Chip Select
31 30 29 28 27 26 25 24
DLYBCS
23 22 21 20 19 18 17 16
–––– PCS
15 14 13 12 11 10 9 8
––––––––
76543210
LLB – – MODFDIS PCSDEC PS MSTR
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This field is only used if Fixed Peripheral Select is active (PS = 0).
If PCSDEC = 0:
PCS = xxx0 NPCS[3:0] = 1110
PCS = xx01 NPCS[3:0] = 1101
PCS = x011 NPCS[3:0] = 1011
PCS = 0111 NPCS[3:0] = 0111
PCS = 1111 forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC = 1:
NPCS[3:0] output signals = PCS.
• DLYBCS: Delay Between Chip Selects
This field defines the delay from NPCS inactive to the activation of another NPCS. The DLYBCS time guarantees non-over-
lapping chip selects and solves bus contentions in case of peripherals having long data float times.
If DLYBCS is less than or equal to six, six MCK periods will be inserted by default.
Otherwise, the following equation determines the delay:
Delay Between Chip Selects DLYBCS
MCK
-------------------------=
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28.7.3 SPI Receive Data Register
Name: SPI_RDR
Access Type: Read-only
• RD: Receive Data
Data received by the SPI Interface is stored in this register right-justified. Unused bits read zero.
• PCS: Peripheral Chip Select
In Master Mode only, these bits indicate the value on the NPCS pins at the end of a transfer. Otherwise, these bits read
zero.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–––– PCS
15 14 13 12 11 10 9 8
RD
76543210
RD
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28.7.4 SPI Transmit Data Register
Name: SPI_TDR
Access Type: Write-only
• TD: Transmit Data
Data to be transmitted by the SPI Interface is stored in this register. Information to be transmitted must be written to the
transmit data register in a right-justified format.
PCS: Peripheral Chip Select
This field is only used if Variable Peripheral Select is active (PS = 1).
If PCSDEC = 0:
PCS = xxx0 NPCS[3:0] = 1110
PCS = xx01 NPCS[3:0] = 1101
PCS = x011 NPCS[3:0] = 1011
PCS = 0111 NPCS[3:0] = 0111
PCS = 1111 forbidden (no peripheral is selected)
(x = don’t care)
If PCSDEC = 1:
NPCS[3:0] output signals = PCS
• LASTXFER: Last Transfer
0 = No effect.
1 = The current NPCS will be deasserted after the character written in TD has been transferred. When CSAAT is set, this
allows to close the communication with the current serial peripheral by raising the corresponding NPCS line as soon as TD
transfer has completed.
This field is only used if Variable Peripheral Select is active (PS = 1).
31 30 29 28 27 26 25 24
–––––––LASTXFER
23 22 21 20 19 18 17 16
–––– PCS
15 14 13 12 11 10 9 8
TD
76543210
TD
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28.7.5 SPI Status Register
Name: SPI_SR
Access Type: Read-only
• RDRF: Receive Data Register Full
0 = No data has been received since the last read of SPI_RDR
1 = Data has been received and the received data has been transferred from the serializer to SPI_RDR since the last read
of SPI_RDR.
• TDRE: Transmit Data Register Empty
0 = Data has been written to SPI_TDR and not yet transferred to the serializer.
1 = The last data written in the Transmit Data Register has been transferred to the serializer.
TDRE equals zero when the SPI is disabled or at reset. The SPI enable command sets this bit to one.
• MODF: Mode Fault Error
0 = No Mode Fault has been detected since the last read of SPI_SR.
1 = A Mode Fault occurred since the last read of the SPI_SR.
• OVRES: Overrun Error Status
0 = No overrun has been detected since the last read of SPI_SR.
1 = An overrun has occurred since the last read of SPI_SR.
An overrun occurs when SPI_RDR is loaded at least twice from the serializer since the last read of the SPI_RDR.
• ENDRX: End of RX buffer
0 = The Receive Counter Register has not reached 0 since the last write in SPI_RCR(1) or SPI_RNCR(1).
1 = The Receive Counter Register has reached 0 since the last write in SPI_RCR(1) or SPI_RNCR(1).
• ENDTX: End of TX buffer
0 = The Transmit Counter Register has not reached 0 since the last write in SPI_TCR(1) or SPI_TNCR(1).
1 = The Transmit Counter Register has reached 0 since the last write in SPI_TCR(1) or SPI_TNCR(1).
• RXBUFF: RX Buffer Full
0 = SPI_RCR(1) or SPI_RNCR(1) has a value other than 0.
1 = Both SPI_RCR(1) and SPI_RNCR(1) have a value of 0.
• TXBUFE: TX Buffer Empty
0 = SPI_TCR(1) or SPI_TNCR(1) has a value other than 0.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–––––––SPIENS
15 14 13 12 11 10 9 8
––––––TXEMPTYNSSR
76543210
TXBUFE RXBUFF ENDTX ENDRX OVRES MODF TDRE RDRF
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1 = Both SPI_TCR(1) and SPI_TNCR(1) have a value of 0.
• NSSR: NSS Rising
0 = No rising edge detected on NSS pin since last read.
1 = A rising edge occurred on NSS pin since last read.
• TXEMPTY: Transmission Registers Empty
0 = As soon as data is written in SPI_TDR.
1 = SPI_TDR and internal shifter are empty. If a transfer delay has been defined, TXEMPTY is set after the completion of
such delay.
• SPIENS: SPI Enable Status
0 = SPI is disabled.
1 = SPI is enabled.
Note: 1. SPI_RCR, SPI_RNCR, SPI_TCR, SPI_TNCR are physically located in the PDC.
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28.7.6 SPI Interrupt Enable Register
Name: SPI_IER
Access Type: Write-only
• RDRF: Receive Data Register Full Interrupt Enable
• TDRE: SPI Transmit Data Register Empty Interrupt Enable
• MODF: Mode Fault Error Interrupt Enable
• OVRES: Overrun Error Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• ENDTX: End of Transmit Buffer Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
• TXBUFE: Transmit Buffer Empty Interrupt Enable
• TXEMPTY: Transmission Registers Empty Enable
• NSSR: NSS Rising Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––TXEMPTYNSSR
76543210
TXBUFE RXBUFF ENDTX ENDRX OVRES MODF TDRE RDRF
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28.7.7 SPI Interrupt Disable Register
Name: SPI_IDR
Access Type: Write-only
• RDRF: Receive Data Register Full Interrupt Disable
• TDRE: SPI Transmit Data Register Empty Interrupt Disable
• MODF: Mode Fault Error Interrupt Disable
• OVRES: Overrun Error Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• ENDTX: End of Transmit Buffer Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
• TXBUFE: Transmit Buffer Empty Interrupt Disable
• TXEMPTY: Transmission Registers Empty Disable
• NSSR: NSS Rising Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––TXEMPTYNSSR
76543210
TXBUFE RXBUFF ENDTX ENDRX OVRES MODF TDRE RDRF
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28.7.8 SPI Interrupt Mask Register
Name: SPI_IMR
Access Type: Read-only
• RDRF: Receive Data Register Full Interrupt Mask
• TDRE: SPI Transmit Data Register Empty Interrupt Mask
• MODF: Mode Fault Error Interrupt Mask
• OVRES: Overrun Error Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• ENDTX: End of Transmit Buffer Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
• TXBUFE: Transmit Buffer Empty Interrupt Mask
• TXEMPTY: Transmission Registers Empty Mask
• NSSR: NSS Rising Interrupt Mask
0 = The corresponding interrupt is not enabled.
1 = The corresponding interrupt is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––TXEMPTYNSSR
76543210
TXBUFE RXBUFF ENDTX ENDRX OVRES MODF TDRE RDRF
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28.7.9 SPI Chip Select Register
Name: SPI_CSR0... SPI_CSR3
Access Type: Read-write
• CPOL: Clock Polarity
0 = The inactive state value of SPCK is logic level zero.
1 = The inactive state value of SPCK is logic level one.
CPOL is used to determine the inactive state value of the serial clock (SPCK). It is used with NCPHA to produce the
required clock/data relationship between master and slave devices.
• NCPHA: Clock Phase
0 = Data is changed on the leading edge of SPCK and captured on the following edge of SPCK.
1 = Data is captured on the leading edge of SPCK and changed on the following edge of SPCK.
NCPHA determines which edge of SPCK causes data to change and which edge causes data to be captured. NCPHA is
used with CPOL to produce the required clock/data relationship between master and slave devices.
• CSAAT: Chip Select Active After Transfer
0 = The Peripheral Chip Select Line rises as soon as the last transfer is achieved.
1 = The Peripheral Chip Select does not rise after the last transfer is achieved. It remains active until a new transfer is
requested on a different chip select.
• BITS: Bits Per Transfer
The BITS field determines the number of data bits transferred. Reserved values should not be used.
31 30 29 28 27 26 25 24
DLYBCT
23 22 21 20 19 18 17 16
DLYBS
15 14 13 12 11 10 9 8
SCBR
76543210
BITS CSAAT – NCPHA CPOL
BITS Bits Per Transfer
0000 8
0001 9
0010 10
0011 11
0100 12
0101 13
0110 14
0111 15
1000 16
1001 Reserved
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• SCBR: Serial Clock Baud Rate
In Master Mode, the SPI Interface uses a modulus counter to derive the SPCK baud rate from the Master Clock MCK. The
Baud rate is selected by writing a value from 1 to 255 in the SCBR field. The following equations determine the SPCK baud
rate:
Programming the SCBR field at 0 is forbidden. Triggering a transfer while SCBR is at 0 can lead to unpredictable results.
At reset, SCBR is 0 and the user has to program it at a valid value before performing the first transfer.
• DLYBS: Delay Before SPCK
This field defines the delay from NPCS valid to the first valid SPCK transition.
When DLYBS equals zero, the NPCS valid to SPCK transition is 1/2 the SPCK clock period.
Otherwise, the following equations determine the delay:
• DLYBCT: Delay Between Consecutive Transfers
This field defines the delay between two consecutive transfers with the same peripheral without removing the chip select.
The delay is always inserted after each transfer and before removing the chip select if needed.
When DLYBCT equals zero, no delay between consecutive transfers is inserted and the clock keeps its duty cycle over the
character transfers.
Otherwise, the following equation determines the delay:
1010 Reserved
1011 Reserved
1100 Reserved
1101 Reserved
1110 Reserved
1111 Reserved
BITS Bits Per Transfer
SPCK Baudrate MCK
SCBR
-----------------=
Delay Before SPCK DLYBS
MCK
---------------------=
Delay Between Consecutive Transfers 32 DLYBCT×
MCK
---------------------------------------=
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29. Two-wire Interface (TWI) SAM7S512/256/128/64/321/32
NOTE: This definition of the TWI does not pertain to SAM7S16/161. For SAM7S16/161, see
Section 30.
29.1 Overview
The Two-wire Interface (TWI) interconnects components on a unique two-wire bus, made up of
one clock line and one data line with speeds of up to 400 Kbits per second, based on a byte-ori-
ented transfer format. It can be used with any Atmel Two-wire Interface bus Serial EEPROM and
I²C compatible device such as Real Time Clock (RTC), Dot Matrix/Graphic LCD Controllers and
Temperature Sensor, to name but a few. The TWI is programmable as master transmitter or
master receiver with sequential or single-byte access. A configurable baud rate generator per-
mits the output data rate to be adapted to a wide range of core clock frequencies. Below, Table
29-1 lists the compatibility level of the Atmel Two-wire Interface and a full I2C compatible device.
Notes: 1. START + b000000001 + Ack + Sr
2. A repeated start condition is only supported in Master Receiver mode. See Section 29.6.5
“Internal Address” on page 301
29.2 List of Abbreviations
Table 29-1. Atmel TWI compatibility with i2C Standard
I2C Standard Atmel TWI
Standard Mode Speed (100 KHz) Supported
Fast Mode Speed (400 KHz) Supported
7 or 10 bits Slave Addressing Supported
START BYTE(1) Not Supported
Repeated Start (Sr) Condition Not Fully Supported(2)
ACK and NACK Management Supported
Slope control and input filtering (Fast mode) Not Supported
Clock stretching Supported
Table 29-2. Abbreviations
Abbreviation Description
TWI Two-wire Interface
A Acknowledge
N Not Acknowledge
PStop
SStart
Sr Repeated Start
DADR Device Address
IADR Internal Address
RRead
WWrite
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29.3 Block Diagram
Figure 29-1. Block Diagram
29.4 Application Block Diagram
Figure 29-2. Application Block Diagram
29.4.1 I/O Lines Description
29.5 Product Dependencies
29.5.1 I/O Lines
Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current
source or pull-up resistor (see Figure 29-2 on page 296). When the bus is free, both lines are
APB Bridge
PMC MCK
Two-wire
Interface
PIO
AIC
TWI
Interrupt
TWCK
TWD
Host with
TWI
Interface
TWD
TWCK
Atmel TWI
Serial EEPROM I²C RTC I²C LCD
Controller
Slave 1 Slave 2 Slave 3
VDD
I²C Temp.
Sensor
Slave 4
Rp: Pull up value as given by the I²C Standard
Rp Rp
Table 29-3. I/O Lines Description
Pin Name Pin Description Type
TWD Two-wire Serial Data Input/Output
TWCK Two-wire Serial Clock Input/Output
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high. The output stages of devices connected to the bus must have an open-drain or open-col-
lector to perform the wired-AND function.
TWD and TWCK pins may be multiplexed with PIO lines. To enable the TWI, the programmer
must perform the following steps:
• Program the PIO controller to:
– Dedicate TWD and TWCK as peripheral lines.
– Define TWD and TWCK as open-drain.
29.5.2 Power Management
• Enable the peripheral clock.
The TWI interface may be clocked through the Power Management Controller (PMC), thus the
programmer must first configure the PMC to enable the TWI clock.
29.5.3 Interrupt
The TWI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). In
order to handle interrupts, the AIC must be programmed before configuring the TWI.
29.6 Functional Description
29.6.1 Transfer format
The data put on the TWD line must be 8 bits long. Data is transferred MSB first; each byte must
be followed by an acknowledgement. The number of bytes per transfer is unlimited (see Figure
29-4 on page 297).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure
29-3 on page 297).
• A high-to-low transition on the TWD line while TWCK is high defines the START condition.
• A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
Figure 29-3. START and STOP Conditions
Figure 29-4. Transfer Format
29.6.2 Modes of Operation
The TWI has two modes of operation:
TWD
TWCK
Start Stop
TWD
TWCK
Start Address R/W Ack Data Ack Data Ack Stop
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• Master transmitter mode
• Master receiver mode
The TWI Control Register (TWI_CR) allows configuration of the interface in Master Mode. In this
mode, it generates the clock according to the value programmed in the Clock Waveform Gener-
ator Register (TWI_CWGR). This register defines the TWCK signal completely, enabling the
interface to be adapted to a wide range of clocks.
29.6.3 Master Transmitter Mode
After the master initiates a Start condition when writing into the Transmit Holding Register,
TWI_THR, it sends a 7-bit slave address, configured in the Master Mode register (DADR in
TWI_MMR), to notify the slave device. The bit following the slave address indicates the transfer
direction, 0 in this case (MREAD = 0 in TWI_MMR).
The TWI transfers require the slave to acknowledge each received byte. During the acknowl-
edge clock pulse (9th pulse), the master releases the data line (HIGH), enabling the slave to pull
it down in order to generate the acknowledge. The master polls the data line during this clock
pulse and sets the Not Acknowledge bit (NACK) in the status register if the slave does not
acknowledge the byte. As with the other status bits, an interrupt can be generated if enabled in
the interrupt enable register (TWI_IER). If the slave acknowledges the byte, the data written in
the TWI_THR, is then shifted in the internal shifter and transferred. When an acknowledge is
detected, the TXRDY bit is set until a new write in the TWI_THR. When no more data is written
into the TWI_THR, the master generates a stop condition to end the transfer. The end of the
complete transfer is marked by the TWI_TXCOMP bit set to one. See Figure 29-5, Figure 29-6,
and Figure 29-7.
Figure 29-5. Master Write with One Data Byte
Figure 29-6. Master Write with Multiple Data Byte
TXCOMP
TXRDY
Write THR (DATA) STOP sent automaticaly
(ACK received and TXRDY = 1)
TWD A DATA AS DADR W P
A DATA n AS DADR W DATA n+5 A PDATA n+x A
TXCOMP
TXRDY
Write THR (Data n) Write THR (Data n+1) Write THR (Data n+x)
Last data sent
STOP sent automaticaly
(ACK received and TXRDY = 1)
TWD
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Figure 29-7. Master Write with One Byte Internal Address and Multiple Data Bytes
29.6.4 Master Receiver Mode
The read sequence begins by setting the START bit. After the start condition has been sent, the
master sends a 7-bit slave address to notify the slave device. The bit following the slave address
indicates the transfer direction, 1 in this case (MREAD = 1 in TWI_MMR). During the acknowl-
edge clock pulse (9th pulse), the master releases the data line (HIGH), enabling the slave to pull
it down in order to generate the acknowledge. The master polls the data line during this clock
pulse and sets the NACK bit in the status register if the slave does not acknowledge the byte.
If an acknowledge is received, the master is then ready to receive data from the slave. After data
has been received, the master sends an acknowledge condition to notify the slave that the data
has been received except for the last data, after the stop condition. See Figure 29-9. When the
RXRDY bit is set in the status register, a character has been received in the receive-holding reg-
ister (TWI_RHR). The RXRDY bit is reset when reading the TWI_RHR.
When a single data byte read is performed, with or without internal address (IADR), the START
and STOP bits must be set at the same time. See Figure 29-8. When a multiple data byte read is
performed, with or without internal address (IADR), the STOP bit must be set after the next-to-
last data received. See Figure 29-9. For Internal Address usage see Section 29.6.5.
Figure 29-8. Master Read with One Data Byte
A IADR(7:0) A DATA n AS DADR W DATA n+5 A PDATA n+x A
TXCOMP
TXRDY
TWD
Write THR (Data n) Write THR (Data n+1) Write THR (Data n+x)
Last data sent
STOP sent automaticaly
(ACK received and TXRDY = 1)
AS DADR R DATA N P
TXCOMP
Write START &
STOP Bit
RXRDY
Read RHR
TWD
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Figure 29-9. Master Read with Multiple Data Bytes
N
AS DADR R DATA n A ADATA (n+1) A DATA (n+m)DATA (n+m)-1 PTWD
TXCOMP
Write START Bit
RXRDY
Write STOP Bit
after next-to-last data read
Read RHR
DATA n
Read RHR
DATA (n+1)
Read RHR
DATA (n+m)-1
Read RHR
DATA (n+m)
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29.6.5 Internal Address
The TWI interface can perform various transfer formats: Transfers with 7-bit slave address
devices and 10-bit slave address devices.
29.6.5.1 7-bit Slave Addressing
When Addressing 7-bit slave devices, the internal address bytes are used to perform random
address (read or write) accesses to reach one or more data bytes, within a memory page loca-
tion in a serial memory, for example. When performing read operations with an internal address,
the TWI performs a write operation to set the internal address into the slave device, and then
switch to Master Receiver mode. Note that the second start condition (after sending the IADR) is
sometimes called “repeated start” (Sr) in I2C fully-compatible devices. See Figure 29-10, Figure
29-11 and Figure 29-12.
The three internal address bytes are configurable through the Master Mode register
(TWI_MMR).
If the slave device supports only a 7-bit address, i.e. no internal address, IADRSZ must be set to
0.
In the figures below the following abbreviations are used:
Figure 29-10. Master Write with One, Two or Three Bytes Internal Address and One Data Byte
Figure 29-11. Master Read with One, Two or Three Bytes Internal Address and One Data Byte
•S Start
•P Stop
•W Write
•R Read
•A Acknowledge
•N Not Acknowledge
•DADR Device Address
•IADR Internal Address
S DADR W A IADR(23:16) A IADR(15:8) A IADR(7:0) A DATA A P
S DADR W A IADR(15:8) A IADR(7:0) A PDATA A
A IADR(7:0) A P
DATA AS DADR W
TWD
Three bytes internal address
Two bytes internal address
One byte internal address
TWD
TWD
SA
S DADR W A IADR(23:16) A IADR(15:8) A IADR(7:0) A
S DADR W A IADR(15:8) A IADR(7:0) A
A IADR(7:0) AS DADR W
DATA N P
S DADR R A
S DADR R A DATA N P
DADR
R DATA N P
TWD
TWD
TWD
Three bytes internal address
Two bytes internal address
One byte internal address
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29.6.5.2 10-bit Slave Addressing
For a slave address higher than 7 bits, the user must configure the address size (IADRSZ) and
set the other slave address bits in the internal address register (TWI_IADR). The two remaining
Internal address bytes, IADR[15:8] and IADR[23:16] can be used the same as in 7-bit Slave
Addressing.
Example: Address a 10-bit device (10-bit device address is b1 b2 b3 b4 b5 b6 b7 b8 b9 b10)
1. Program IADRSZ = 1,
2. Program DADR with 1 1 1 1 0 b1 b2 (b1 is the MSB of the 10-bit address, b2, etc.)
3. Program TWI_IADR with b3 b4 b5 b6 b7 b8 b9 b10 (b10 is the LSB of the 10-bit
address)
Figure 29-12 below shows a byte write to an Atmel AT24LC512 EEPROM. This demonstrates
the use of internal addresses to access the device.
Figure 29-12. Internal Address Usage
S
T
A
R
T
M
S
B
Device
Address
0
L
S
B
R
/
W
A
C
K
M
S
B
W
R
I
T
E
A
C
K
A
C
K
L
S
B
A
C
K
FIRST
WORD ADDRESS
SECOND
WORD ADDRESS DATA
S
T
O
P
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29.6.6 Read/Write Flowcharts
The following flowcharts shown in Figure 29-13, Figure 29-14 on page 304, Figure 29-15 on
page 305, Figure 29-16 on page 306, Figure 29-17 on page 307 and Figure 29-18 on page 308
give examples for read and write operations. A polling or interrupt method can be used to check
the status bits. The interrupt method requires that the interrupt enable register (TWI_IER) be
configured first.
Figure 29-13. TWI Write Operation with Single Data Byte without Internal Address
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address (DADR)
- Transfer direction bit
Write ==> bit MREAD = 0
Load Transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Read Status register
TXCOMP = 1?
Transfer finished
Ye s
Ye s
BEGIN
No
No
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Figure 29-14. TWI Write Operation with Single Data Byte and Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address (DADR)
- Internal address size (IADRSZ)
- Transfer direction bit
Write ==> bit MREAD = 0
Load transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Read Status register
TXCOMP = 1?
Transfer finished
Set the internal address
TWI_IADR = address
Ye s
Ye s
No
No
305
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Figure 29-15. TWI Write Operation with Multiple Data Bytes with or without Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Write ==> bit MREAD = 0
Internal address size = 0?
Load Transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Data to send?
Read Status register
TXCOMP = 1?
END
BEGIN
Set the internal address
TWI_IADR = address
Ye s
TWI_THR = data to send
Ye s
Ye s
Ye s
No
No
No
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
306
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Figure 29-16. TWI Read Operation with Single Data Byte without Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Transfer direction bit
Read ==> bit MREAD = 1
Start the transfer
TWI_CR = START | STOP
Read status register
RXRDY = 1?
Read Status register
TXCOMP = 1?
END
BEGIN
Ye s
Ye s
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Read Receive Holding Register
No
No
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Figure 29-17. TWI Read Operation with Single Data Byte and Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Internal address size (IADRSZ)
- Transfer direction bit
Read ==> bit MREAD = 1
Read Status register
TXCOMP = 1?
END
BEGIN
Ye s
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Ye s
Set the internal address
TWI_IADR = address
Start the transfer
TWI_CR = START | STOP
Read Status register
RXRDY = 1?
Read Receive Holding register
No
No
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Figure 29-18. TWI Read Operation with Multiple Data Bytes with or without Internal Address
Internal address size = 0?
Start the transfer
TWI_CR = START
Stop the transfer
TWI_CR = STOP
Read Status register
RXRDY = 1?
Last data to read
but one?
Read status register
TXCOMP = 1?
END
Set the internal address
TWI_IADR = address
Ye s
Ye s
Ye s
No
Ye s
Read Receive Holding register (TWI_RHR)
No
Set the Control register:
- Master enable
TWI_CR = MSEN
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Read ==> bit MREAD = 1
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
No
Read Status register
RXRDY = 1?
Ye s
Read Receive Holding register (TWI_RHR)
No
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29.7 Two-wire Interface (TWI) User Interface
Table 29-4. Register Mapping
Offset Register Name Access Reset
0x0000 Control Register TWI_CR Write-only N/A
0x0004 Master Mode Register TWI_MMR Read-write 0x0000
0x0008 Reserved - - -
0x000C Internal Address Register TWI_IADR Read-write 0x0000
0x0010 Clock Waveform Generator Register TWI_CWGR Read-write 0x0000
0x0020 Status Register TWI_SR Read-only 0x0008
0x0024 Interrupt Enable Register TWI_IER Write-only N/A
0x0028 Interrupt Disable Register TWI_IDR Write-only N/A
0x002C Interrupt Mask Register TWI_IMR Read-only 0x0000
0x0030 Receive Holding Register TWI_RHR Read-only 0x0000
0x0034 Transmit Holding Register TWI_THR Read-write 0x0000
0x0038 - 0x00FC Reserved – – –
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29.7.1 TWI Control Register
Register Name: TWI_CR
Access Type: Write-only
• START: Send a START Condition
0 = No effect.
1 = A frame beginning with a START bit is transmitted according to the features defined in the mode register.
This action is necessary when the TWI peripheral wants to read data from a slave. When configured in Master Mode with a
write operation, a frame is sent as soon as the user writes a character in the Transmit Holding Register (TWI_THR).
• STOP: Send a STOP Condition
0 = No effect.
1 = STOP Condition is sent just after completing the current byte transmission in master read mode.
– In single data byte master read, the START and STOP must both be set.
– In multiple data bytes master read, the STOP must be set after the last data received but one.
– In master read mode, if a NACK bit is received, the STOP is automatically performed.
– In multiple data write operation, when both THR and shift register are empty, a STOP condition is automatically
sent.
• MSEN: TWI Master Transfer Enabled
0 = No effect.
1 = If MSDIS = 0, the master data transfer is enabled.
• MSDIS: TWI Master Transfer Disabled
0 = No effect.
1 = The master data transfer is disabled, all pending data is transmitted. The shifter and holding characters (if they contain
data) are transmitted in case of write operation. In read operation, the character being transferred must be completely
received before disabling.
• SWRST: Software Reset
0 = No effect.
1 = Equivalent to a system reset.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
SWRST – – – MSDIS MSEN STOP START
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29.7.2 TWI Master Mode Register
Register Name:TWI_MMR
Address Type: Read-write
• IADRSZ: Internal Device Address Size
• MREAD: Master Read Direction
0 = Master write direction.
1 = Master read direction.
• DADR: Device Address
The device address is used to access slave devices in read or write mode.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–DADR
15 14 13 12 11 10 9 8
–––MREAD–– IADRSZ
76543210
––––––––
Table 29-5.
IADRSZ[9:8]
0 0 No internal device address (Byte command protocol)
0 1 One-byte internal device address
1 0 Two-byte internal device address
1 1 Three-byte internal device address
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29.7.3 TWI Internal Address Register
Register Name:TWI_IADR
Access Type: Read-write
• IADR: Internal Address
0, 1, 2 or 3 bytes depending on IADRSZ.
– Low significant byte address in 10-bit mode addresses.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
IADR
15 14 13 12 11 10 9 8
IADR
76543210
IADR
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29.7.4 TWI Clock Waveform Generator Register
Register Name: TWI_CWGR
Access Type: Read-write
• CLDIV: Clock Low Divider
The SCL low period is defined as follows:
• CHDIV: Clock High Divider
The SCL high period is defined as follows:
• CKDIV: Clock Divider
The CKDIV is used to increase both SCL high and low periods.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––– CKDIV
15 14 13 12 11 10 9 8
CHDIV
76543210
CLDIV
Tlow CLDIV(2CKDIV
×()3)+TMCK
×=
Thigh CHDIV(2CKDIV
×()3)+TMCK
×=
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29.7.5 TWI Status Register
Register Name:TWI_SR
Access Type: Read-only
• TXCOMP: Transmission Completed
0 = During the length of the current frame.
1 = When both holding and shift registers are empty and STOP condition has been sent, or when MSEN is set (enable
TWI).
• RXRDY: Receive Holding Register Ready
0 = No character has been received since the last TWI_RHR read operation.
1 = A byte has been received in the TWI_RHR since the last read.
• TXRDY: Transmit Holding Register Ready
0 = The transmit holding register has not been transferred into shift register. Set to 0 when writing into TWI_THR register.
1 = As soon as data byte is transferred from TWI_THR to internal shifter or if a NACK error is detected, TXRDY is set at the
same time as TXCOMP and NACK. TXRDY is also set when MSEN is set (enable TWI).
• NACK: Not Acknowledged
0 = Each data byte has been correctly received by the far-end side TWI slave component.
1 = A data byte has not been acknowledged by the slave component. Set at the same time as TXCOMP. Reset after read.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––NACK
76543210
–––––TXRDYRXRDYTXCOMP
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29.7.6 TWI Interrupt Enable Register
Register Name:TWI_IER
Access Type: Write-only
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• NACK: Not Acknowledge
0 = No effect.
1 = Enables the corresponding interrupt.
29.7.7 TWI Interrupt Disable Register
Register Name:TWI_IDR
Access Type: Write-only
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• NACK: Not Acknowledge
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––NACK
76543210
–––––TXRDYRXRDYTXCOMP
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––NACK
76543210
–––––TXRDYRXRDYTXCOMP
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29.7.8 TWI Interrupt Mask Register
Register Name:TWI_IMR
Access Type: Read-only
• TXCOMP: Transmission Completed
• RXRDY: Receive Holding Register Ready
• TXRDY: Transmit Holding Register Ready
• NACK: Not Acknowledge
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
29.7.9 TWI Receive Holding Register
Register Name: TWI_RHR
Access Type: Read-only
• RXDATA: Receive Holding Data
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––NACK
76543210
–––––TXRDYRXRDYTXCOMP
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
RXDATA
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29.7.10 TWI Transmit Holding Register
Register Name:TWI_THR
Access Type: Read-write
• TXDATA: Transmit Holding Data
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
TXDATA
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30. Two Wire Interface (TWI) SAM7S161/16
NOTE: This definition of the TWI does not pertain to SAM7S512/256/128/65/32/321. For
SAM7S512/256/128/65/32/321, see Section 29.
30.1 Overview
The Atmel Two-wire Interface (TWI) interconnects components on a unique two-wire bus, made up of one clock
line and one data line with speeds of up to 400 Kbits per second, based on a byte-oriented transfer format. It can
be used with any Atmel Two-wire Interface bus Serial EEPROM and I²C compatible device such as Real Time
Clock (RTC), Dot Matrix/Graphic LCD Controllers and Temperature Sensor, to name but a few. The TWI is pro-
grammable as a master or a slave with sequential or single-byte access. Multiple master capability is supported.
Arbitration of the bus is performed internally and puts the TWI in slave mode automatically if the bus arbitration is
lost.
A configurable baud rate generator permits the output data rate to be adapted to a wide range of core clock
frequencies.
Below, Table 30-1 lists the compatibility level of the Atmel Two-wire Interface in Master Mode and a full I2C compat-
ible device.
Note: 1. START + b000000001 + Ack + Sr
30.2 List of Abbreviations
Table 30-1. Atmel TWI compatibility with i2C Standard
I2C Standard Atmel TWI
Standard Mode Speed (100 KHz) Supported
Fast Mode Speed (400 KHz) Supported
7 or 10 bits Slave Addressing Supported
START BYTE(1) Not Supported
Repeated Start (Sr) Condition Supported
ACK and NACK Management Supported
Slope control and input filtering (Fast mode) Not Supported
Clock stretching Supported
Table 30-2. Abbreviations
Abbreviation Description
TWI Two-wire Interface
A Acknowledge
NA Non Acknowledge
PStop
SStart
Sr Repeated Start
SADR Slave Address
ADR Any address except SADR
R Read
WWrite
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30.3 Block Diagram
Figure 30-1. Block Diagram
30.4 Application Block Diagram
Figure 30-2. Application Block Diagram
30.4.1 I/O Lines Description
30.5 Product Dependencies
30.5.1 I/O Lines
Both TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current source or pull-up
resistor (see Figure 30-2 on page 320). When the bus is free, both lines are high. The output stages of devices
connected to the bus must have an open-drain or open-collector to perform the wired-AND function.
APB Bridge
PMC MCK
Two-wire
Interface
PIO
AIC
TWI
Interrupt
TWCK
TWD
Host with
TWI
Interface
TWD
TWCK
Atmel TWI
Serial EEPROM I²C RTC I²C LCD
Controller
Slave 1 Slave 2 Slave 3
VDD
I²C Temp.
Sensor
Slave 4
Rp: Pull up value as given by the I²C Standard
Rp Rp
Table 30-3. I/O Lines Description
Pin Name Pin Description Type
TWD Two-wire Serial Data Input/Output
TWCK Two-wire Serial Clock Input/Output
321
SAM7S Series [DATASHEET]
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TWD and TWCK pins may be multiplexed with PIO lines. To enable the TWI, the programmer must perform the fol-
lowing steps:
• Program the PIO controller to:
– Dedicate TWD and TWCK as peripheral lines.
– Define TWD and TWCK as open-drain.
30.5.2 Power Management
• Enable the peripheral clock.
The TWI interface may be clocked through the Power Management Controller (PMC), thus the programmer must
first configure the PMC to enable the TWI clock.
30.5.3 Interrupt
The TWI interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). In order to handle
interrupts, the AIC must be programmed before configuring the TWI.
30.6 Functional Description
30.6.1 Transfer Format
The data put on the TWD line must be 8 bits long. Data is transferred MSB first; each byte must be followed by an
acknowledgement. The number of bytes per transfer is unlimited (see Figure 30-4).
Each transfer begins with a START condition and terminates with a STOP condition (see Figure 30-3).
• A high-to-low transition on the TWD line while TWCK is high defines the START condition.
• A low-to-high transition on the TWD line while TWCK is high defines a STOP condition.
Figure 30-3. START and STOP Conditions
Figure 30-4. Transfer Format
30.6.2 Modes of Operation
The TWI has six modes of operations:
• Master transmitter mode
• Master receiver mode
• Multi-master transmitter mode
TWD
TWCK
Start Stop
TWD
TWCK
Start Address R/W Ack Data Ack Data Ack Stop
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• Multi-master receiver mode
• Slave transmitter mode
• Slave receiver mode
These modes are described in the following chapters.
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30.7 Master Mode
30.7.1 Definition
The Master is the device which starts a transfer, generates a clock and stops it.
30.7.2 Application Block Diagram
Figure 30-5. Master Mode Typical Application Block Diagram
30.7.3 Programming Master Mode
The following registers have to be programmed before entering Master mode:
1. DADR (+ IADRSZ + IADR if a 10 bit device is addressed): The device address is used to access slave
devices in read or write mode.
2. CKDIV + CHDIV + CLDIV: Clock Waveform.
3. SVDIS: Disable the slave mode.
4. MSEN: Enable the master mode.
30.7.4 Master Transmitter Mode
After the master initiates a Start condition when writing into the Transmit Holding Register, TWI_THR, it sends a 7-
bit slave address, configured in the Master Mode register (DADR in TWI_MMR), to notify the slave device. The bit
following the slave address indicates the transfer direction, 0 in this case (MREAD = 0 in TWI_MMR).
The TWI transfers require the slave to acknowledge each received byte. During the acknowledge clock pulse (9th
pulse), the master releases the data line (HIGH), enabling the slave to pull it down in order to generate the
acknowledge. The master polls the data line during this clock pulse and sets the Not Acknowledge bit (NACK) in
the status register if the slave does not acknowledge the byte. As with the other status bits, an interrupt can be
generated if enabled in the interrupt enable register (TWI_IER). If the slave acknowledges the byte, the data writ-
ten in the TWI_THR, is then shifted in the internal shifter and transferred. When an acknowledge is detected, the
TXRDY bit is set until a new write in the TWI_THR. When no more data is written into the TWI_THR, the master
generates a stop condition to end the transfer. The end of the complete transfer is marked by the TWI_TXCOMP
bit set to one. See Figure 30-6, Figure 30-7, and Figure 30-8.
Host with
TWI
Interface
TWD
TWCK
Atmel TWI
Serial EEPROM I²C RTC I²C LCD
Controller
Slave 1 Slave 2 Slave 3
VDD
I²C Temp.
Sensor
Slave 4
Rp: Pull up value as given by the I²C Standard
Rp Rp
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Figure 30-6. Master Write with One Data Byte
Figure 30-7. Master Write with Multiple Data Byte
Figure 30-8. Master Write with One Byte Internal Address and Multiple Data Bytes
30.7.5 Master Receiver Mode
The read sequence begins by setting the START bit. After the start condition has been sent, the master sends a 7-
bit slave address to notify the slave device. The bit following the slave address indicates the transfer direction, 1 in
this case (MREAD = 1 in TWI_MMR). During the acknowledge clock pulse (9th pulse), the master releases the
data line (HIGH), enabling the slave to pull it down in order to generate the acknowledge. The master polls the data
line during this clock pulse and sets the NACK bit in the status register if the slave does not acknowledge the byte.
If an acknowledge is received, the master is then ready to receive data from the slave. After data has been
received, the master sends an acknowledge condition to notify the slave that the data has been received except for
the last data, after the stop condition. See Figure 30-9. When the RXRDY bit is set in the status register, a charac-
ter has been received in the receive-holding register (TWI_RHR). The RXRDY bit is reset when reading the
TWI_RHR.
When a single data byte read is performed, with or without internal address (IADR), the START and STOP bits
must be set at the same time. See Figure 30-9. When a multiple data byte read is performed, with or without inter-
TXCOMP
TXRDY
Write THR (DATA) STOP sent automaticaly
(ACK received and TXRDY = 1)
TWD A DATA AS DADR W P
A DATA n AS DADR W DATA n+5 A PDATA n+x A
TXCOMP
TXRDY
Write THR (Data n) Write THR (Data n+1) Write THR (Data n+x)
Last data sent
STOP sent automaticaly
(ACK received and TXRDY = 1)
TWD
A IADR(7:0) A DATA n AS DADR W DATA n+5 A PDATA n+x A
TXCOMP
TXRDY
TWD
Write THR (Data n) Write THR (Data n+1) Write THR (Data n+x)
Last data sent
STOP sent automaticaly
(ACK received and TXRDY = 1)
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nal address (IADR), the STOP bit must be set after the next-to-last data received. See Figure 30-10. For Internal
Address usage see Section 30.7.6.
Figure 30-9. Master Read with One Data Byte
Figure 30-10. Master Read with Multiple Data Bytes
30.7.6 Internal Address
The TWI interface can perform various transfer formats: Transfers with 7-bit slave address devices and 10-bit slave
address devices.
30.7.6.1 7-bit Slave Addressing
When Addressing 7-bit slave devices, the internal address bytes are used to perform random address (read or
write) accesses to reach one or more data bytes, within a memory page location in a serial memory, for example.
When performing read operations with an internal address, the TWI performs a write operation to set the internal
address into the slave device, and then switch to Master Receiver mode. Note that the second start condition (after
sending the IADR) is sometimes called “repeated start” (Sr) in I2C fully-compatible devices. See Figure 30-12. See
Figure 30-11 and Figure 30-13 for Master Write operation with internal address.
The three internal address bytes are configurable through the Master Mode register (TWI_MMR).
If the slave device supports only a 7-bit address, i.e. no internal address, IADRSZ must be set to 0.
In the figures below the following abbreviations are used:
AS DADR R DATA N P
TXCOMP
Write START &
STOP Bit
RXRDY
Read RHR
TWD
N
AS DADR R DATA n A ADATA (n+1) A DATA (n+m)DATA (n+m)-1 PTWD
TXCOMP
Write START Bit
RXRDY
Write STOP Bit
after next-to-last data read
Read RHR
DATA n
Read RHR
DATA (n+1)
Read RHR
DATA (n+m)-1
Read RHR
DATA (n+m)
•S Start
•Sr Repeated Start
•P Stop
•W Write
•R Read
•A Acknowledge
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Figure 30-11. Master Write with One, Two or Three Bytes Internal Address and One Data Byte
Figure 30-12. Master Read with One, Two or Three Bytes Internal Address and One Data Byte
30.7.6.2 10-bit Slave Addressing
For a slave address higher than 7 bits, the user must configure the address size (IADRSZ) and set the other slave
address bits in the internal address register (TWI_IADR). The two remaining Internal address bytes, IADR[15:8]
and IADR[23:16] can be used the same as in 7-bit Slave Addressing.
Example: Address a 10-bit device (10-bit device address is b1 b2 b3 b4 b5 b6 b7 b8 b9 b10)
1. Program IADRSZ = 1,
2. Program DADR with 1 1 1 1 0 b1 b2 (b1 is the MSB of the 10-bit address, b2, etc.)
3. Program TWI_IADR with b3 b4 b5 b6 b7 b8 b9 b10 (b10 is the LSB of the 10-bit address)
4.
Figure 30-13 below shows a byte write to an Atmel AT24LC512 EEPROM. This demonstrates the use of internal
addresses to access the device.
Figure 30-13. Internal Address Usage
•N Not Acknowledge
•DADR Device Address
•IADR Internal Address
S DADR W A IADR(23:16) A IADR(15:8) A IADR(7:0) A DATA A P
S DADR W A IADR(15:8) A IADR(7:0) A P
DATA A
A IADR(7:0) A P
DATA AS DADR W
TWD
Three bytes internal address
Two bytes internal address
One byte internal address
TWD
TWD
S DADR WA IADR(23:16) A IADR(15:8) AIADR(7:0) A
S DADR W A IADR(15:8) A IADR(7:0) A
AIADR(7:0) A
S DADR W
DATA N P
Sr DADR R A
Sr DADR R A DATA N P
Sr DADR RA DATA NP
TWD
TWD
TWD
Three bytes internal address
Two bytes internal address
One byte internal address
S
T
A
R
T
M
S
B
Device
Address
0
L
S
B
R
/
W
A
C
K
M
S
B
W
R
I
T
E
A
C
K
A
C
K
L
S
B
A
C
K
FIRST
WORD ADDRESS
SECOND
WORD ADDRESS DATA
S
T
O
P
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30.7.7 Read-write Flowcharts
The following flowcharts shown in Figure 30-14, Figure 30-15 on page 329, Figure 30-16 on page 330, Figure 30-
17 on page 331, Figure 30-18 on page 332 and Figure 30-19 on page 333 give examples for read and write opera-
tions. A polling or interrupt method can be used to check the status bits. The interrupt method requires that the
interrupt enable register (TWI_IER) be configured first.
Figure 30-14. TWI Write Operation with Single Data Byte without Internal Address
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address (DADR)
- Transfer direction bit
Write ==> bit MREAD = 0
Load Transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Read Status register
TXCOMP = 1?
Transfer finished
Ye s
Ye s
BEGIN
No
No
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Figure 30-15. TWI Write Operation with Single Data Byte and Internal Address
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address (DADR)
- Internal address size (IADRSZ)
- Transfer direction bit
Write ==> bit MREAD = 0
Load transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Read Status register
TXCOMP = 1?
Transfer finished
Set the internal address
TWI_IADR = address
Ye s
Ye s
No
No
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Figure 30-16. TWI Write Operation with Multiple Data Bytes with or without Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Write ==> bit MREAD = 0
Internal address size = 0?
Load Transmit register
TWI_THR = Data to send
Read Status register
TXRDY = 1?
Data to send?
Read Status register
TXCOMP = 1?
END
BEGIN
Set the internal address
TWI_IADR = address
Ye s
TWI_THR = data to send
Ye s
Ye s
Ye s
No
No
No
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
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Figure 30-17. TWI Read Operation with Single Data Byte without Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (IADRSZ)
- Transfer direction bit
Read ==> bit MREAD = 1
Read Status register
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Ye s
Set the internal address
TWI_IADR = address
Start the transfer
TWI_CR = START | STOP
Read Status register
RXRDY = 1?
Read Receive Holding register
No
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Figure 30-18. TWI Read Operation with Single Data Byte and Internal Address
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (IADRSZ)
- Transfer direction bit
Read ==> bit MREAD = 1
Read Status register
TXCOMP = 1?
END
BEGIN
Ye s
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
Ye s
Set the internal address
TWI_IADR = address
Start the transfer
TWI_CR = START | STOP
Read Status register
RXRDY = 1?
Read Receive Holding register
No
No
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Figure 30-19. TWI Read Operation with Multiple Data Bytes with or without Internal Address
Internal address size = 0?
Start the transfer
TWI_CR = START
Stop the transfer
TWI_CR = STOP
Read Status register
RXRDY = 1?
Last data to read
but one?
Read status register
TXCOMP = 1?
END
Set the internal address
TWI_IADR = address
Ye s
Ye s
Ye s
No
Ye s
Read Receive Holding register (TWI_RHR)
No
Set the Control register:
- Master enable
TWI_CR = MSEN + SVDIS
Set the Master Mode register:
- Device slave address
- Internal address size (if IADR used)
- Transfer direction bit
Read ==> bit MREAD = 1
BEGIN
Set TWI clock
(CLDIV, CHDIV, CKDIV) in TWI_CWGR
(Needed only once)
No
Read Status register
RXRDY = 1?
Ye s
Read Receive Holding register (TWI_RHR)
No
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30.8 Multi-master Mode
30.8.1 Definition
More than one master may handle the bus at the same time without data corruption by using arbitration.
Arbitration starts as soon as two or more masters place information on the bus at the same time, and stops (arbitra-
tion is lost) for the master that intends to send a logical one while the other master sends a logical zero.
As soon as arbitration is lost by a master, it stops sending data and listens to the bus in order to detect a stop.
When the stop is detected, the master who has lost arbitration may put its data on the bus by respecting arbitration.
Arbitration is illustrated in Figure 30-21 on page 335.
30.8.2 Different Multi-master Modes
Two multi-master modes may be distinguished:
1. TWI is considered as a Master only and will never be addressed.
2. TWI may be either a Master or a Slave and may be addressed.
Note: In both Multi-master modes arbitration is supported.
30.8.2.1 TWI as Master Only
In this mode, TWI is considered as a Master only (MSEN is always at one) and must be driven like a Master with
the ARBLST (ARBitration Lost) flag in addition.
If arbitration is lost (ARBLST = 1), the programmer must reinitiate the data transfer.
If the user starts a transfer (ex.: DADR + START + W + Write in THR) and if the bus is busy, the TWI automatically
waits for a STOP condition on the bus to initiate the transfer (see Figure 30-20 on page 335).
Note: The state of the bus (busy or free) is not indicated in the user interface.
30.8.2.2 TWI as Master or Slave
The automatic reversal from Master to Slave is not supported in case of a lost arbitration.
Then, in the case where TWI may be either a Master or a Slave, the programmer must manage the pseudo Multi-
master mode described in the steps below.
1. Program TWI in Slave mode (SADR + MSDIS + SVEN) and perform Slave Access (if TWI is addressed).
2. If TWI has to be set in Master mode, wait until TXCOMP flag is at 1.
3. Program Master mode (DADR + SVDIS + MSEN) and start the transfer (ex: START + Write in THR).
4. As soon as the Master mode is enabled, TWI scans the bus in order to detect if it is busy or free. When the
bus is considered as free, TWI initiates the transfer.
5. As soon as the transfer is initiated and until a STOP condition is sent, the arbitration becomes relevant
and the user must monitor the ARBLST flag.
6. If the arbitration is lost (ARBLST is set to 1), the user must program the TWI in Slave mode in the case
where the Master that won the arbitration wanted to access the TWI.
7. If TWI has to be set in Slave mode, wait until TXCOMP flag is at 1 and then program the Slave mode.
Note: In the case where the arbitration is lost and TWI is addressed, TWI will not acknowledge even if it is programmed in
Slave mode as soon as ARBLST is set to 1. Then, the Master must repeat SADR.
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Figure 30-20. Programmer Sends Data While the Bus is Busy
Figure 30-21. Arbitration Cases
The flowchart shown in Figure 30-22 on page 336 gives an example of read and write operations in Multi-master
mode.
TWCK
TWD DATA sent by a master
STOP sent by the master START sent by the TWI
DATA sent by the TWI
Bus is busy
Bus is free
A transfer is programmed
(DADR + W + START + Write THR) Transfer is initiated
TWI DATA transfer Transfer is kept
Bus is considered as free
TWCK
Bus is busy Bus is free
A transfer is programmed
(DADR + W + START + Write THR) Transfer is initiated
TWI DATA transfer Transfer is kept
Bus is considered as free
Data from a Master
Data from TWI S0
S00
1
1
1
ARBLST
S0
S00
1
1
1
TWD S00
1
11
11
Arbitration is lost
TWI stops sending data
P
S0
1
P0
11
11
Data from the master Data from the TWI
Arbitration is lost
The master stops sending data
Transfer is stopped
Transfer is programmed again
(DADR + W + START + Write THR)
TWCK
TWD
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Figure 30-22. Multi-master Flowchart
Programm the SLAVE mode:
SADR + MSDIS + SVEN
SVACC = 1 ?
TXCOMP = 1 ?
GACC = 1 ?
Decoding of the
programming sequence
Prog seq
OK ?
Change SADR
SVREAD = 0 ?
Read Status Register
RXRDY= 0 ?
Read TWI_RHR
TXRDY= 1 ?
EOSACC = 1 ?
Write in TWI_THR
Need to perform
a master access ?
Program the Master mode
DADR + SVDIS + MSEN + CLK + R / W
Read Status Register
ARBLST = 1 ?
MREAD = 1 ?
TXRDY= 0 ?
Write in TWI_THR
Data to send ?
RXRDY= 0 ?
Read TWI_RHR Data to read?
Stop transfer
Read Status Register
TXCOMP = 0 ?
GENERAL CALL TREATMENT
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
START
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30.9 Slave Mode
30.9.1 Definition
The Slave Mode is defined as a mode where the device receives the clock and the address from another device
called the master.
In this mode, the device never initiates and never completes the transmission (START, REPEATED_START and
STOP conditions are always provided by the master).
30.9.2 Application Block Diagram
Figure 30-23. Slave Mode Typical Application Block Diagram
30.9.3 Programming Slave Mode
The following fields must be programmed before entering Slave mode:
1. SADR (TWI_SMR): The slave device address is used in order to be accessed by master devices in read
or write mode.
2. MSDIS (TWI_CR): Disable the master mode.
3. SVEN (TWI_CR): Enable the slave mode.
As the device receives the clock, values written in TWI_CWGR are not taken into account.
30.9.4 Receiving Data
After a Start or Repeated Start condition is detected and if the address sent by the Master matches with the Slave
address programmed in the SADR (Slave ADdress) field, SVACC (Slave ACCess) flag is set and SVREAD (Slave
READ) indicates the direction of the transfer.
SVACC remains high until a STOP condition or a repeated START is detected. When such a condition is detected,
EOSACC (End Of Slave ACCess) flag is set.
30.9.4.1 Read Sequence
In the case of a Read sequence (SVREAD is high), TWI transfers data written in the TWI_THR (TWI Transmit
Holding Register) until a STOP condition or a REPEATED_START + an address different from SADR is detected.
Note that at the end of the read sequence TXCOMP (Transmission Complete) flag is set and SVACC reset.
As soon as data is written in the TWI_THR, TXRDY (Transmit Holding Register Ready) flag is reset, and it is set
when the shift register is empty and the sent data acknowledged or not. If the data is not acknowledged, the NACK
flag is set.
Note that a STOP or a repeated START always follows a NACK.
Host with
TWI
Interface
TWD
TWCK
LCD Controller
Slave 1 Slave 2 Slave 3
RR
VDD
Host with TWI
Interface
Host with TWI
Interface
Master
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See Figure 30-24 on page 338.
30.9.4.2 Write Sequence
In the case of a Write sequence (SVREAD is low), the RXRDY (Receive Holding Register Ready) flag is set as
soon as a character has been received in the TWI_RHR (TWI Receive Holding Register). RXRDY is reset when
reading the TWI_RHR.
TWI continues receiving data until a STOP condition or a REPEATED_START + an address different from SADR
is detected. Note that at the end of the write sequence TXCOMP flag is set and SVACC reset.
See Figure 30-25 on page 339.
30.9.4.3 Clock Synchronization Sequence
In the case where TWI_THR or TWI_RHR is not written/read in time, TWI performs a clock synchronization.
Clock stretching information is given by the SCLWS (Clock Wait state) bit.
See Figure 30-27 on page 341 and Figure 30-28 on page 342.
30.9.4.4 General Call
In the case where a GENERAL CALL is performed, GACC (General Call ACCess) flag is set.
After GACC is set, it is up to the programmer to interpret the meaning of the GENERAL CALL and to decode the
new address programming sequence.
See Figure 30-26 on page 339.
30.9.5 Data Transfer
30.9.5.1 Read Operation
The read mode is defined as a data requirement from the master.
After a START or a REPEATED START condition is detected, the decoding of the address starts. If the slave
address (SADR) is decoded, SVACC is set and SVREAD indicates the direction of the transfer.
Until a STOP or REPEATED START condition is detected, TWI continues sending data loaded in the TWI_THR
register.
If a STOP condition or a REPEATED START + an address different from SADR is detected, SVACC is reset.
Figure 30-24 on page 338 describes the write operation.
Figure 30-24. Read Access Ordered by a MASTER
Write THR Read RHR
SVREAD has to be taken into account only while SVACC is active
TWD
TXRDY
NACK
SVACC
SVREAD
EOSVACC
SADRS ADR R NA R A DATA A A DATA NA S/SrDATA NA P/S/Sr
SADR matches,
TWI answers with an ACK
SADR does not match,
TWI answers with a NACK ACK/NACK from the Master
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Notes: 1. When SVACC is low, the state of SVREAD becomes irrelevant.
2. TXRDY is reset when data has been transmitted from TWI_THR to the shift register and set when this data has been
acknowledged or non acknowledged.
30.9.5.2 Write Operation
The write mode is defined as a data transmission from the master.
After a START or a REPEATED START, the decoding of the address starts. If the slave address is decoded,
SVACC is set and SVREAD indicates the direction of the transfer (SVREAD is low in this case).
Until a STOP or REPEATED START condition is detected, TWI stores the received data in the TWI_RHR register.
If a STOP condition or a REPEATED START + an address different from SADR is detected, SVACC is reset.
Figure 30-25 on page 339 describes the Write operation.
Figure 30-25. Write Access Ordered by a Master
Notes: 1. When SVACC is low, the state of SVREAD becomes irrelevant.
2. RXRDY is set when data has been transmitted from the shift register to the TWI_RHR and reset when this data is read.
30.9.5.3 General Call
The general call is performed in order to change the address of the slave.
If a GENERAL CALL is detected, GACC is set.
After the detection of General Call, it is up to the programmer to decode the commands which come afterwards.
In case of a WRITE command, the programmer has to decode the programming sequence and program a new
SADR if the programming sequence matches.
Figure 30-26 on page 339 describes the General Call access.
Figure 30-26. Master Performs a General Call
RXRDY
Read RHR
SVREAD has to be taken into account only while SVACC is active
TWD
SVACC
SVREAD
EOSVACC
SADR does not match,
TWI answers with a NACK
SADRS ADR W NA W A DATA A A DATA NA S/SrDATA NA P/S/Sr
SADR matches,
TWI answers with an ACK
0000000 + W
GENERAL CALL P
SA
GENERAL CALL Reset or write DADD A New SADR
DATA 1 A DATA 2 A
A
New SADR
Programming sequence
TXD
GCACC
SVACC
RESET command = 00000110X
WRITE command = 00000100X
Reset after read
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Note: This method allows the user to create an own programming sequence by choosing the programming bytes and the
number of them. The programming sequence has to be provided to the master.
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30.9.5.4 Clock Synchronization
In both read and write modes, it may happen that TWI_THR/TWI_RHR buffer is not filled /emptied before the emis-
sion/reception of a new character. In this case, to avoid sending/receiving undesired data, a clock stretching
mechanism is implemented.
Clock Synchronization in Read Mode
The clock is tied low if the shift register is empty and if a STOP or REPEATED START condition was not detected.
It is tied low until the shift register is loaded.
Figure 30-27 on page 341 describes the clock synchronization in Read mode.
Figure 30-27. Clock Synchronization in Read Mode
Notes: 1. TXRDY is reset when data has been written in the TWI_TH to the shift register and set when this data has been acknowl-
edged or non acknowledged.
2. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from
SADR.
3. SCLWS is automatically set when the clock synchronization mechanism is started.
DATA 1
The clock is stretched after the ACK, the state of TWD is undefined during clock stretching
SCLWS
SVACC
SVREAD
TXRDY
TWCK
TWI_THR
TXCOMP
The data is memorized in TWI_THR until a new value is written
TWI_THR is transmitted to the shift register Ack or Nack from the master
DATA 0DATA 0 DATA 2
1
2
1
CLOCK is tied low by the TWI
as long as THR is empty
SSADR
SRDATA 0AADATA 1 AD ATA 2 NA S
XXXXXXX
2
Write THR
As soon as a START is detected
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6175M–ATARM–26-Oct-12
Clock Synchronization in Write Mode
The clock is tied low if the shift register and the TWI_RHR is full. If a STOP or REPEATED_START condition was
not detected, it is tied low until TWI_RHR is read.
Figure 30-28 on page 342 describes the clock synchronization in Read mode.
Figure 30-28. Clock Synchronization in Write Mode
Notes: 1. At the end of the read sequence, TXCOMP is set after a STOP or after a REPEATED_START + an address different from
SADR.
2. SCLWS is automatically set when the clock synchronization mechanism is started and automatically reset when the mecha-
nism is finished.
Rd DATA0 Rd DATA1 Rd DATA2
SVACC
SVREAD
RXRDY
SCLWS
TXCOMP
DATA 1 D ATA 2
SCL is stretched on the last bit of DATA1
As soon as a START is detected
TWCK
TWD
TWI_RHR
CLOCK is tied low by the TWI as long as RHR is full
DATA0 is not read in the RHR
ADRS SADR W ADATA 0A A DATA 2DATA 1 S
NA
343
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.9.5.5 Reversal after a Repeated Start
Reversal of Read to Write
The master initiates the communication by a read command and finishes it by a write command.
Figure 30-29 on page 343 describes the repeated start + reversal from Read to Write mode.
Figure 30-29. Repeated Start + Reversal from Read to Write Mode
1. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
Reversal of Write to Read
The master initiates the communication by a write command and finishes it by a read command.Figure 30-30 on
page 343 describes the repeated start + reversal from Write to Read mode.
Figure 30-30. Repeated Start + Reversal from Write to Read Mode
Notes: 1. In this case, if TWI_THR has not been written at the end of the read command, the clock is automatically stretched before
the ACK.
2. TXCOMP is only set at the end of the transmission because after the repeated start, SADR is detected again.
S SADR R ADATA 0A D ATA 1 SADRSr
NA
W A DATA 2 A DATA 3 A P
Cleared after read
DATA 0 D ATA 1
DATA 2 DATA 3
SVACC
SVREAD
TWD
TWI_THR
TWI_RHR
EOSACC
TXRDY
RXRDY
TXCOMP
As soon as a START is detected
S SADR W ADATA 0A D ATA 1 SADRSr
A
R A DATA 2 A D ATA 3 N A P
Cleared after read
DATA 0
DATA 2 D ATA 3
DATA 1
TXCOMP
TXRDY
RXRDY
As soon as a START is detected
Read TWI_RHR
SVACC
SVREAD
TWD
TWI_RHR
TWI_THR
EOSACC
344
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.9.6 Read Write Flowcharts
The flowchart shown in Figure 30-31 on page 344 gives an example of read and write operations in Slave mode. A
polling or interrupt method can be used to check the status bits. The interrupt method requires that the interrupt
enable register (TWI_IER) be configured first.
Figure 30-31. Read Write Flowchart in Slave Mode
Set the SLAVE mode:
SADR + MSDIS + SVEN
SVACC = 1 ?
TXCOMP = 1 ?
GACC = 1 ?
Decoding of the
programming sequence
Prog seq
OK ?
Change SADR
SVREAD = 0 ?
Read Status Register
RXRDY= 0 ?
Read TWI_RHR
TXRDY= 1 ?
EOSACC = 1 ?
Write in TWI_THR
END
GENERAL CALL TREATMENT
345
SAM7S Series [DATASHEET]
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30.10 Two-wire Interface (TWI) User Interface
Table 30-4. Register Mapping
Offset Register Name Access Reset
0x00 Control Register TWI_CR Write-only N / A
0x04 Master Mode Register TWI_MMR Read-write 0x00000000
0x08 Slave Mode Register TWI_SMR Read-write 0x00000000
0x0C Internal Address Register TWI_IADR Read-write 0x00000000
0x10 Clock Waveform Generator Register TWI_CWGR Read-write 0x00000000
0x20 Status Register TWI_SR Read-only 0x0000F009
0x24 Interrupt Enable Register TWI_IER Write-only N / A
0x28 Interrupt Disable Register TWI_IDR Write-only N / A
0x2C Interrupt Mask Register TWI_IMR Read-only 0x00000000
0x30 Receive Holding Register TWI_RHR Read-only 0x00000000
0x34 Transmit Holding Register TWI_THR Write-only 0x00000000
0x38 - 0xFC Reserved – – –
–––
346
SAM7S Series [DATASHEET]
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30.10.1 TWI Control Register
Name: TWI_CR
Access: Write-only
Reset Value: 0x00000000
• START: Send a START Condition
0 = No effect.
1 = A frame beginning with a START bit is transmitted according to the features defined in the mode register.
This action is necessary when the TWI peripheral wants to read data from a slave. When configured in Master Mode with a
write operation, a frame is sent as soon as the user writes a character in the Transmit Holding Register (TWI_THR).
• STOP: Send a STOP Condition
0 = No effect.
1 = STOP Condition is sent just after completing the current byte transmission in master read mode.
– In single data byte master read, the START and STOP must both be set.
– In multiple data bytes master read, the STOP must be set after the last data received but one.
– In master read mode, if a NACK bit is received, the STOP is automatically performed.
– In multiple data write operation, when both THR and shift register are empty, a STOP condition is automatically
sent.
• MSEN: TWI Master Mode Enabled
0 = No effect.
1 = If MSDIS = 0, the master mode is enabled.
Note: Switching from Slave to Master mode is only permitted when TXCOMP = 1.
• MSDIS: TWI Master Mode Disabled
0 = No effect.
1 = The master mode is disabled, all pending data is transmitted. The shifter and holding characters (if it contains data) are
transmitted in case of write operation. In read operation, the character being transferred must be completely received
before disabling.
• SVEN: TWI Slave Mode Enabled
0 = No effect.
1 = If SVDIS = 0, the slave mode is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
SWRST – SVDIS SVEN MSDIS MSEN STOP START
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SAM7S Series [DATASHEET]
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Note: Switching from Master to Slave mode is only permitted when TXCOMP = 1.
• SVDIS: TWI Slave Mode Disabled
0 = No effect.
1 = The slave mode is disabled. The shifter and holding characters (if it contains data) are transmitted in case of read oper-
ation. In write operation, the character being transferred must be completely received before disabling.
• SWRST: Software Reset
0 = No effect.
1 = Equivalent to a system reset.
348
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30.10.2 TWI Master Mode Register
Name: TWI_MMR
Access: Read-write
Reset Value: 0x00000000
• IADRSZ: Internal Device Address Size
• MREAD: Master Read Direction
0 = Master write direction.
1 = Master read direction.
• DADR: Device Address
The device address is used to access slave devices in read or write mode. Those bits are only used in Master mode.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–DADR
15 14 13 12 11 10 9 8
–––MREAD–– IADRSZ
76543210
––––––––
IADRSZ[9:8]
0 0 No internal device address
0 1 One-byte internal device address
1 0 Two-byte internal device address
1 1 Three-byte internal device address
349
SAM7S Series [DATASHEET]
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30.10.3 TWI Slave Mode Register
Name: TWI_SMR
Access: Read-write
Reset Value: 0x00000000
• SADR: Slave Address
The slave device address is used in Slave mode in order to be accessed by master devices in read or write mode.
SADR must be programmed before enabling the Slave mode or after a general call. Writes at other times have no effect.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–SADR
15 14 13 12 11 10 9 8
––––––
76543210
––––––––
350
SAM7S Series [DATASHEET]
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30.10.4 TWI Internal Address Register
Name: TWI_IADR
Access: Read-write
Reset Value: 0x00000000
• IADR: Internal Address
0, 1, 2 or 3 bytes depending on IADRSZ.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
IADR
15 14 13 12 11 10 9 8
IADR
76543210
IADR
351
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.10.5 TWI Clock Waveform Generator Register
Name: TWI_CWGR
Access: Read-write
Reset Value: 0x00000000
TWI_CWGR is only used in Master mode.
• CLDIV: Clock Low Divider
The SCL low period is defined as follows:
• CHDIV: Clock High Divider
The SCL high period is defined as follows:
• CKDIV: Clock Divider
The CKDIV is used to increase both SCL high and low periods.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
CKDIV
15 14 13 12 11 10 9 8
CHDIV
76543210
CLDIV
Tlow CLDIV(2CKDIV
×()4)+TMCK
×=
Thigh CHDIV(2CKDIV
×()4)+TMCK
×=
352
SAM7S Series [DATASHEET]
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30.10.6 TWI Status Register
Name: TWI_SR
Access: Read-only
Reset Value: 0x0000F009
• TXCOMP: Transmission Completed (automatically set / reset)
TXCOMP used in Master mode:
0 = During the length of the current frame.
1 = When both holding and shifter registers are empty and STOP condition has been sent.
TXCOMP behavior in Master mode can be seen in Figure 30-8 on page 324 and in Figure 30-10 on page 325.
TXCOMP used in Slave mode:
0 = As soon as a Start is detected.
1 = After a Stop or a Repeated Start + an address different from SADR is detected.
TXCOMP behavior in Slave mode can be seen in Figure 30-27 on page 341, Figure 30-28 on page 342, Figure 30-29 on
page 343 and Figure 30-30 on page 343.
• RXRDY: Receive Holding Register Ready (automatically set / reset)
0 = No character has been received since the last TWI_RHR read operation.
1 = A byte has been received in the TWI_RHR since the last read.
RXRDY behavior in Master mode can be seen in Figure 30-10 on page 325.
RXRDY behavior in Slave mode can be seen in Figure 30-25 on page 339, Figure 30-28 on page 342, Figure 30-29 on
page 343 and Figure 30-30 on page 343.
• TXRDY: Transmit Holding Register Ready (automatically set / reset)
TXRDY used in Master mode:
0 = The transmit holding register has not been transferred into shift register. Set to 0 when writing into TWI_THR register.
1 = As soon as a data byte is transferred from TWI_THR to internal shifter or if a NACK error is detected, TXRDY is set at
the same time as TXCOMP and NACK. TXRDY is also set when MSEN is set (enable TWI).
TXRDY behavior in Master mode can be seen in Figure 30-8 on page 324.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
EOSACC SCLWS ARBLST NACK
76543210
– OVRE GACC SVACC SVREAD TXRDY RXRDY TXCOMP
353
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
TXRDY used in Slave mode:
0 = As soon as data is written in the TWI_THR, until this data has been transmitted and acknowledged (ACK or NACK).
1 = It indicates that the TWI_THR is empty and that data has been transmitted and acknowledged.
If TXRDY is high and if a NACK has been detected, the transmission will be stopped. Thus when TRDY = NACK = 1, the
programmer must not fill TWI_THR to avoid losing it.
TXRDY behavior in Slave mode can be seen in Figure 30-24 on page 338, Figure 30-27 on page 341, Figure 30-29 on
page 343 and Figure 30-30 on page 343.
• SVREAD: Slave Read (automatically set / reset)
This bit is only used in Slave mode. When SVACC is low (no Slave access has been detected) SVREAD is irrelevant.
0 = Indicates that a write access is performed by a Master.
1 = Indicates that a read access is performed by a Master.
SVREAD behavior can be seen in Figure 30-24 on page 338, Figure 30-25 on page 339, Figure 30-29 on page 343 and
Figure 30-30 on page 343.
• SVACC: Slave Access (automatically set / reset)
This bit is only used in Slave mode.
0 = TWI is not addressed. SVACC is automatically cleared after a NACK or a STOP condition is detected.
1 = Indicates that the address decoding sequence has matched (A Master has sent SADR). SVACC remains high until a
NACK or a STOP condition is detected.
SVACC behavior can be seen in Figure 30-24 on page 338, Figure 30-25 on page 339, Figure 30-29 on page 343 and Fig-
ure 30-30 on page 343.
• GACC: General Call Access (clear on read)
This bit is only used in Slave mode.
0 = No General Call has been detected.
1 = A General Call has been detected. After the detection of General Call, the programmer decoded the commands that fol-
low and the programming sequence.
GACC behavior can be seen in Figure 30-26 on page 339.
• OVRE: Overrun Error (clear on read)
This bit is only used in Master mode.
0 = TWI_RHR has not been loaded while RXRDY was set
1 = TWI_RHR has been loaded while RXRDY was set. Reset by read in TWI_SR when TXCOMP is set.
• NACK: Not Acknowledged (clear on read)
NACK used in Master mode:
0 = Each data byte has been correctly received by the far-end side TWI slave component.
1 = A data byte has not been acknowledged by the slave component. Set at the same time as TXCOMP.
354
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
NACK used in Slave Read mode:
0 = Each data byte has been correctly received by the Master.
1 = In read mode, a data byte has not been acknowledged by the Master. When NACK is set the programmer must not fill
TWI_THR even if TXRDY is set, because it means that the Master will stop the data transfer or re initiate it.
Note that in Slave Write mode all data are acknowledged by the TWI.
• ARBLST: Arbitration Lost (clear on read)
This bit is only used in Master mode.
0: Arbitration won.
1: Arbitration lost. Another master of the TWI bus has won the multi-master arbitration. TXCOMP is set at the same time.
• SCLWS: Clock Wait State (automatically set / reset)
This bit is only used in Slave mode.
0 = The clock is not stretched.
1 = The clock is stretched. TWI_THR / TWI_RHR buffer is not filled / emptied before the emission / reception of a new
character.
SCLWS behavior can be seen in Figure 30-27 on page 341 and Figure 30-28 on page 342.
• EOSACC: End Of Slave Access (clear on read)
This bit is only used in Slave mode.
0 = A slave access is being performing.
1 = The Slave Access is finished. End Of Slave Access is automatically set as soon as SVACC is reset.
EOSACC behavior can be seen in Figure 30-29 on page 343 and Figure 30-30 on page 343
355
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.10.7 TWI Interrupt Enable Register
Name: TWI_IER
Access: Write-only
Reset Value: 0x00000000
• TXCOMP: Transmission Completed Interrupt Enable
• RXRDY: Receive Holding Register Ready Interrupt Enable
• TXRDY: Transmit Holding Register Ready Interrupt Enable
• SVACC: Slave Access Interrupt Enable
• GACC: General Call Access Interrupt Enable
• OVRE: Overrun Error Interrupt Enable
• NACK: Not Acknowledge Interrupt Enable
• ARBLST: Arbitration Lost Interrupt Enable
• SCL_WS: Clock Wait State Interrupt Enable
• EOSACC: End Of Slave Access Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
EOSACC SCL_WS ARBLST NACK
76543210
– OVRE GACC SVACC – TXRDY RXRDY TXCOMP
356
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.10.8 TWI Interrupt Disable Register
Name: TWI_IDR
Access: Write-only
Reset Value: 0x00000000
• TXCOMP: Transmission Completed Interrupt Disable
• RXRDY: Receive Holding Register Ready Interrupt Disable
• TXRDY: Transmit Holding Register Ready Interrupt Disable
• SVACC: Slave Access Interrupt Disable
• GACC: General Call Access Interrupt Disable
• OVRE: Overrun Error Interrupt Disable
• NACK: Not Acknowledge Interrupt Disable
• ARBLST: Arbitration Lost Interrupt Disable
• SCL_WS: Clock Wait State Interrupt Disable
• EOSACC: End Of Slave Access Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
EOSACC SCL_WS ARBLST NACK
76543210
– OVRE GACC SVACC – TXRDY RXRDY TXCOMP
357
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.10.9 TWI Interrupt Mask Register
Name: TWI_IMR
Access: Read-only
Reset Value: 0x00000000
• TXCOMP: Transmission Completed Interrupt Mask
• RXRDY: Receive Holding Register Ready Interrupt Mask
• TXRDY: Transmit Holding Register Ready Interrupt Mask
• SVACC: Slave Access Interrupt Mask
• GACC: General Call Access Interrupt Mask
• OVRE: Overrun Error Interrupt Mask
• NACK: Not Acknowledge Interrupt Mask
• ARBLST: Arbitration Lost Interrupt Mask
• SCL_WS: Clock Wait State Interrupt Mask
• EOSACC: End Of Slave Access Interrupt Mask
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
EOSACC SCL_WS ARBLST NACK
76543210
– OVRE GACC SVACC – TXRDY RXRDY TXCOMP
358
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
30.10.10 TWI Receive Holding Register
Name: TWI_RHR
Access: Read-only
Reset Value: 0x00000000
• RXDATA: Master or Slave Receive Holding Data
30.10.11 TWI Transmit Holding Register
Name: TWI_THR
Access: Read-write
Reset Value: 0x00000000
• TXDATA: Master or Slave Transmit Holding Data
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
RXDATA
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
TXDATA
359
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31. Universal Synchronous Asynchronous Receiver Transceiver (USART)
31.1 Overview
The Universal Synchronous Asynchronous Receiver Transceiver (USART) provides one full duplex universal syn-
chronous asynchronous serial link. Data frame format is widely programmable (data length, parity, number of stop
bits) to support a maximum of standards. The receiver implements parity error, framing error and overrun error
detection. The receiver time-out enables handling variable-length frames and the transmitter timeguard facilitates
communications with slow remote devices. Multidrop communications are also supported through address bit han-
dling in reception and transmission.
The USART features three test modes: remote loopback, local loopback and automatic echo.
The USART supports specific operating modes providing interfaces on RS485 buses, with ISO7816 T = 0 or T = 1
smart card slots, and infrared transceivers and connection to modem ports. The hardware handshaking feature
enables an out-of-band flow control by automatic management of the pins RTS and CTS.
The USART supports the connection to the Peripheral DMA Controller, which enables data transfers to the trans-
mitter and from the receiver. The PDC provides chained buffer management without any intervention of the
processor.
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SAM7S Series [DATASHEET]
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31.2 Block Diagram
Figure 31-1. SAM7S512/256/128/64/321/161 USART Block Diagram
Peripheral DMA
Controller
Channel Channel
AIC
Receiver
USART
Interrupt
RXD
TXD
SCK
USART PIO
Controller
CTS
RTS
DTR
DSR
DCD
RI
Transmitter
Modem
Signals
Control
Baud Rate
Generator
User Interface
PMC
MCK
SLCK
DIV MCK/DIV
APB
361
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-2. SAM7S32/16 USART Block Diagram
31.3 Application Block Diagram
Figure 31-3. SAM7S512/256/128/64/321/161 Application Block Diagram
Peripheral DMA
Controller
Channel Channel
AIC
Receiver
USART
Interrupt
RXD
TXD
SCK
USART PIO
Controller
CTS
RTS
Transmitter
Baud Rate
Generator
User Interface
PMC
MCK
SLCK
DIV MCK/DIV
APB
Smart
Card
Slot
USART
RS232
Drivers
Modem
RS485
Drivers
Differential
Bus
IrDA
Transceivers
Modem
Driver
Field Bus
Driver
EMV
Driver IrDA
Driver
IrLAP
RS232
Drivers
Serial
Port
Serial
Driver
PPP
PSTN
362
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-4. SAM7S32/16 Application Block Diagram
31.4 I/O Lines Description
Note: 1. Does not pertain to SAM7S32/16
Smart
Card
Slot
USART
RS485
Drivers
Differential
Bus
IrDA
Transceivers
Field Bus
Driver
EMV
Driver IrDA
Driver
IrLAP
RS232
Drivers
Serial
Port
Serial
Driver
PPP
Table 31-1. I/O Line Description
Name Description Type Active Level
SCK Serial Clock I/O
TXD Transmit Serial Data I/O
RXD Receive Serial Data Input
RI(1) Ring Indicator Input Low
DSR(1) Data Set Ready Input Low
DCD(1) Data Carrier Detect Input Low
DTR(1) Data Terminal Ready Output Low
CTS Clear to Send Input Low
RTS Request to Send Output Low
363
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31.5 Product Dependencies
31.5.1 I/O Lines
The pins used for interfacing the USART may be multiplexed with the PIO lines. The programmer must first pro-
gram the PIO controller to assign the desired USART pins to their peripheral function. If I/O lines of the USART are
not used by the application, they can be used for other purposes by the PIO Controller.
To prevent the TXD line from falling when the USART is disabled, the use of an internal pull up is mandatory. If the
hardware handshaking feature or Modem mode is used, the internal pull up on TXD must also be enabled.
All the pins of the modems may or may not be implemented on the USART. Only USART1 is fully equipped with all
the modem signals. On USARTs not equipped with the corresponding pin, the associated control bits and statuses
have no effect on the behavior of the USART.
31.5.2 Power Management
The USART is not continuously clocked. The programmer must first enable the USART Clock in the Power Man-
agement Controller (PMC) before using the USART. However, if the application does not require USART
operations, the USART clock can be stopped when not needed and be restarted later. In this case, the USART will
resume its operations where it left off.
Configuring the USART does not require the USART clock to be enabled.
31.5.3 Interrupt
The USART interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using
the USART interrupt requires the AIC to be programmed first. Note that it is not recommended to use the USART
interrupt line in edge sensitive mode.
364
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31.6 Functional Description
The USART is capable of managing several types of serial synchronous or asynchronous communications.
It supports the following communication modes:
• 5- to 9-bit full-duplex asynchronous serial communication
– MSB- or LSB-first
– 1, 1.5 or 2 stop bits
– Parity even, odd, marked, space or none
– By 8 or by 16 over-sampling receiver frequency
– Optional hardware handshaking
– Optional modem signals management (SAM7S512/256/128/64/321/161)
– Optional break management
– Optional multidrop serial communication
• High-speed 5- to 9-bit full-duplex synchronous serial communication
– MSB- or LSB-first
– 1 or 2 stop bits
– Parity even, odd, marked, space or none
– By 8 or by 16 over-sampling frequency
– Optional hardware handshaking
– Optional modem signals management (SAM7S512/256/128/64/321/161)
– Optional break management
– Optional multidrop serial communication
• RS485 with driver control signal
• ISO7816, T0 or T1 protocols for interfacing with smart cards
– NACK handling, error counter with repetition and iteration limit
• InfraRed IrDA Modulation and Demodulation
• Test modes
– Remote loopback, local loopback, automatic echo
31.6.1 Baud Rate Generator
The Baud Rate Generator provides the bit period clock named the Baud Rate Clock to both the receiver and the
transmitter.
The Baud Rate Generator clock source can be selected by setting the USCLKS field in the Mode Register
(US_MR) between:
• the Master Clock MCK
• a division of the Master Clock, the divider being product dependent, but generally set to 8
• the external clock, available on the SCK pin
The Baud Rate Generator is based upon a 16-bit divider, which is programmed with the CD field of the Baud Rate
Generator Register (US_BRGR). If CD is programmed at 0, the Baud Rate Generator does not generate any clock.
If CD is programmed at 1, the divider is bypassed and becomes inactive.
If the external SCK clock is selected, the duration of the low and high levels of the signal provided on the SCK pin
must be longer than a Master Clock (MCK) period. The frequency of the signal provided on SCK must be at least
4.5 times lower than MCK.
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SAM7S Series [DATASHEET]
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Figure 31-5. Baud Rate Generator
31.6.1.1 Baud Rate in Asynchronous Mode
If the USART is programmed to operate in asynchronous mode, the selected clock is first divided by CD, which is
field programmed in the Baud Rate Generator Register (US_BRGR). The resulting clock is provided to the receiver
as a sampling clock and then divided by 16 or 8, depending on the programming of the OVER bit in US_MR.
If OVER is set to 1, the receiver sampling is 8 times higher than the baud rate clock. If OVER is cleared, the sam-
pling is performed at 16 times the baud rate clock.
The following formula performs the calculation of the Baud Rate.
This gives a maximum baud rate of MCK divided by 8, assuming that MCK is the highest possible clock and that
OVER is programmed at 1.
31.6.1.2 Baud Rate Calculation Example
Table 31-2 shows calculations of CD to obtain a baud rate at 38400 bauds for different source clock frequencies.
This table also shows the actual resulting baud rate and the error.
MCK/DIV
16-bit Counter
0
Baud Rate
Clock
CD
CD
Sampling
Divider
0
1
>1
Sampling
Clock
Reserved
MCK
SCK
USCLKS
OVER
SCK
SYNC
SYNC
USCLKS = 3
1
0
2
3
0
1
0
1
FIDI
Baudrate SelectedClock
82 Over–()CD()
----------------------------------------------=
Table 31-2. Baud Rate Example (OVER = 0)
Source Clock
Expected Baud
Rate Calculation Result CD Actual Baud Rate Error
MHz Bit/s Bit/s
3 686 400 38 400 6.00 6 38 400.00 0.00%
4 915 200 38 400 8.00 8 38 400.00 0.00%
5 000 000 38 400 8.14 8 39 062.50 1.70%
7 372 800 38 400 12.00 12 38 400.00 0.00%
8 000 000 38 400 13.02 13 38 461.54 0.16%
12 000 000 38 400 19.53 20 37 500.00 2.40%
12 288 000 38 400 20.00 20 38 400.00 0.00%
14 318 180 38 400 23.30 23 38 908.10 1.31%
366
SAM7S Series [DATASHEET]
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The baud rate is calculated with the following formula:
The baud rate error is calculated with the following formula. It is not recommended to work with an error higher than
5%.
31.6.1.3 SAM7S512/156/128 Fractional Baud Rate in Asynchronous Mode
The Baud Rate generator previously defined is subject to the following limitation: the output frequency changes by
only integer multiples of the reference frequency. An approach to this problem is to integrate a fractional N clock
generator that has a high resolution. The generator architecture is modified to obtain Baud Rate changes by a frac-
tion of the reference source clock. This fractional part is programmed with the FP field in the Baud Rate Generator
Register (US_BRGR). If FP is not 0, the fractional part is activated. The resolution is one eighth of the clock divider.
This feature is only available when using USART normal mode. The fractional Baud Rate is calculated using the
following formula:
The modified architecture is presented below:
14 745 600 38 400 24.00 24 38 400.00 0.00%
18 432 000 38 400 30.00 30 38 400.00 0.00%
24 000 000 38 400 39.06 39 38 461.54 0.16%
24 576 000 38 400 40.00 40 38 400.00 0.00%
25 000 000 38 400 40.69 40 38 109.76 0.76%
32 000 000 38 400 52.08 52 38 461.54 0.16%
32 768 000 38 400 53.33 53 38 641.51 0.63%
33 000 000 38 400 53.71 54 38 194.44 0.54%
40 000 000 38 400 65.10 65 38 461.54 0.16%
50 000 000 38 400 81.38 81 38 580.25 0.47%
Table 31-2. Baud Rate Example (OVER = 0) (Continued)
Source Clock
Expected Baud
Rate Calculation Result CD Actual Baud Rate Error
BaudRate MCK CD 16×⁄=
Error 1ExpectedBaudRate
ActualBaudRate
---------------------------------------------------------
⎝⎠
⎛⎞
–=
Baudrate SelectedClock
82 Over–()CD FP
8
--------+
⎝⎠
⎛⎞
⎝⎠
⎛⎞
------------------------------------------------------------------=
367
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-6. SAM7S512/256/128 Fractional Baud Rate Generator
31.6.1.4 Baud Rate in Synchronous Mode
If the USART is programmed to operate in synchronous mode, the selected clock is simply divided by the field CD
in US_BRGR.
In synchronous mode, if the external clock is selected (USCLKS = 3), the clock is provided directly by the signal on
the USART SCK pin. No division is active. The value written in US_BRGR has no effect. The external clock fre-
quency must be at least 4.5 times lower than the system clock.
When either the external clock SCK or the internal clock divided (MCK/DIV) is selected, the value programmed in
CD must be even if the user has to ensure a 50:50 mark/space ratio on the SCK pin. If the internal clock MCK is
selected, the Baud Rate Generator ensures a 50:50 duty cycle on the SCK pin, even if the value programmed in
CD is odd.
31.6.1.5 Baud Rate in ISO 7816 Mode
The ISO7816 specification defines the bit rate with the following formula:
where:
• B is the bit rate
• Di is the bit-rate adjustment factor
• Fi is the clock frequency division factor
• f is the ISO7816 clock frequency (Hz)
Di is a binary value encoded on a 4-bit field, named DI, as represented in Table 31-3.
MCK/DIV
16-bit Counter
0
Baud Rate
Clock
CD
CD
Sampling
Divider
0
1
>1
Sampling
Clock
Reserved
MCK
SCK
USCLKS
OVER
SCK
SYNC
SYNC
USCLKS = 3
1
0
2
3
0
1
0
1
FIDI
glitch-free
logic
Modulus
Control
FP
FP
BaudRate SelectedClock
CD
-----------------------------------------=
BDi
Fi
------f×=
Table 31-3. Binary and Decimal Values for Di
DI field 0001 0010 0011 0100 0101 0110 1000 1001
Di (decimal)1 2 4 8 163212 20
368
SAM7S Series [DATASHEET]
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Fi is a binary value encoded on a 4-bit field, named FI, as represented in Table 31-4.
Table 31-5 shows the resulting Fi/Di Ratio, which is the ratio between the ISO7816 clock and the baud rate clock.
If the USART is configured in ISO7816 Mode, the clock selected by the USCLKS field in the Mode Register
(US_MR) is first divided by the value programmed in the field CD in the Baud Rate Generator Register
(US_BRGR). The resulting clock can be provided to the SCK pin to feed the smart card clock inputs. This means
that the CLKO bit can be set in US_MR.
This clock is then divided by the value programmed in the FI_DI_RATIO field in the FI_DI_Ratio register
(US_FIDI). This is performed by the Sampling Divider, which performs a division by up to 2047 in ISO7816 Mode.
The non-integer values of the Fi/Di Ratio are not supported and the user must program the FI_DI_RATIO field to a
value as close as possible to the expected value.
The FI_DI_RATIO field resets to the value 0x174 (372 in decimal) and is the most common divider between the
ISO7816 clock and the bit rate (Fi = 372, Di = 1).
Figure 31-7 shows the relation between the Elementary Time Unit, corresponding to a bit time, and the ISO 7816
clock.
Figure 31-7. Elementary Time Unit (ETU)
Table 31-4. Binary and Decimal Values for Fi
FI field 0000 0001 0010 0011 0100 0101 0110 1001 1010 1011 1100 1101
Fi (decimal 372 372 558 744 1116 1488 1860 512 768 1024 1536 2048
Table 31-5. Possible Values for the Fi/Di Ratio
Fi/Di 372 558 774 1116 1488 1806 512 768 1024 1536 2048
1 372 558 744 1116 1488 1860 512 768 1024 1536 2048
2 186 279 372 558 744 930 256 384 512 768 1024
4 93 139.5 186 279 372 465 128 192 256 384 512
8 46.5 69.75 93 139.5 186 232.5 64 96 128 192 256
16 23.25 34.87 46.5 69.75 93 116.2 32 48 64 96 128
32 11.62 17.43 23.25 34.87 46.5 58.13 16 24 32 48 64
12 31 46.5 62 93 124 155 42.66 64 85.33 128 170.6
20 18.6 27.9 37.2 55.8 74.4 93 25.6 38.4 51.2 76.8 102.4
1 ETU
ISO7816 Clock
on SCK
ISO7816 I/O Line
on TXD
FI_DI_RATIO
ISO7816 Clock Cycles
369
SAM7S Series [DATASHEET]
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31.6.2 Receiver and Transmitter Control
After reset, the receiver is disabled. The user must enable the receiver by setting the RXEN bit in the Control Reg-
ister (US_CR). However, the receiver registers can be programmed before the receiver clock is enabled.
After reset, the transmitter is disabled. The user must enable it by setting the TXEN bit in the Control Register
(US_CR). However, the transmitter registers can be programmed before being enabled.
The Receiver and the Transmitter can be enabled together or independently.
At any time, the software can perform a reset on the receiver or the transmitter of the USART by setting the corre-
sponding bit, RSTRX and RSTTX respectively, in the Control Register (US_CR). The software resets clear the
status flag and reset internal state machines but the user interface configuration registers hold the value configured
prior to software reset. Regardless of what the receiver or the transmitter is performing, the communication is
immediately stopped.
The user can also independently disable the receiver or the transmitter by setting RXDIS and TXDIS respectively
in US_CR. If the receiver is disabled during a character reception, the USART waits until the end of reception of the
current character, then the reception is stopped. If the transmitter is disabled while it is operating, the USART waits
the end of transmission of both the current character and character being stored in the Transmit Holding Register
(US_THR). If a timeguard is programmed, it is handled normally.
31.6.3 Synchronous and Asynchronous Modes
31.6.3.1 Transmitter Operations
The transmitter performs the same in both synchronous and asynchronous operating modes (SYNC = 0 or SYNC
= 1). One start bit, up to 9 data bits, one optional parity bit and up to two stop bits are successively shifted out on
the TXD pin at each falling edge of the programmed serial clock.
The number of data bits is selected by the CHRL field and the MODE 9 bit in the Mode Register (US_MR). Nine
bits are selected by setting the MODE 9 bit regardless of the CHRL field. The parity bit is set according to the PAR
field in US_MR. The even, odd, space, marked or none parity bit can be configured. The MSBF field in US_MR
configures which data bit is sent first. If written at 1, the most significant bit is sent first. At 0, the less significant bit
is sent first. The number of stop bits is selected by the NBSTOP field in US_MR. The 1.5 stop bit is supported in
asynchronous mode only.
Figure 31-8. Character Transmit
The characters are sent by writing in the Transmit Holding Register (US_THR). The transmitter reports two status
bits in the Channel Status Register (US_CSR): TXRDY (Transmitter Ready), which indicates that US_THR is
empty and TXEMPTY, which indicates that all the characters written in US_THR have been processed. When the
current character processing is completed, the last character written in US_THR is transferred into the Shift Regis-
ter of the transmitter and US_THR becomes empty, thus TXRDY raises.
Both TXRDY and TXEMPTY bits are low when the transmitter is disabled. Writing a character in US_THR while
TXRDY is low has no effect and the written character is lost.
D0 D1 D2 D3 D4 D5 D6 D7
TXD
Start
Bit
Parity
Bit
Stop
Bit
Example: 8-bit, Parity Enabled One Stop
Baud Rate
Clock
370
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-9. Transmitter Status
31.6.3.2 Asynchronous Receiver
If the USART is programmed in asynchronous operating mode (SYNC = 0), the receiver oversamples the RXD
input line. The oversampling is either 16 or 8 times the Baud Rate clock, depending on the OVER bit in the Mode
Register (US_MR).
The receiver samples the RXD line. If the line is sampled during one half of a bit time at 0, a start bit is detected
and data, parity and stop bits are successively sampled on the bit rate clock.
If the oversampling is 16, (OVER at 0), a start is detected at the eighth sample at 0. Then, data bits, parity bit and
stop bit are sampled on each 16 sampling clock cycle. If the oversampling is 8 (OVER at 1), a start bit is detected
at the fourth sample at 0. Then, data bits, parity bit and stop bit are sampled on each 8 sampling clock cycle.
The number of data bits, first bit sent and parity mode are selected by the same fields and bits as the transmitter,
i.e. respectively CHRL, MODE9, MSBF and PAR. For the synchronization mechanism only, the number of stop
bits has no effect on the receiver as it considers only one stop bit, regardless of the field NBSTOP, so that resyn-
chronization between the receiver and the transmitter can occur. Moreover, as soon as the stop bit is sampled, the
receiver starts looking for a new start bit so that resynchronization can also be accomplished when the transmitter
is operating with one stop bit.
Figure 31-10 and Figure 31-11 illustrate start detection and character reception when USART operates in asyn-
chronous mode.
D0 D1 D2 D3 D4 D5 D6 D7
TXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
Start
Bit
Write
US_THR
D0 D1 D2 D3 D4 D5 D6 D7 Parity
Bit
Stop
Bit
TXRDY
TXEMPTY
371
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-10. Asynchronous Start Detection
Figure 31-11. Asynchronous Character Reception
31.6.3.3 Synchronous Receiver
In synchronous mode (SYNC = 1), the receiver samples the RXD signal on each rising edge of the Baud Rate
Clock. If a low level is detected, it is considered as a start. All data bits, the parity bit and the stop bits are sampled
and the receiver waits for the next start bit. Synchronous mode operations provide a high speed transfer capability.
Configuration fields and bits are the same as in asynchronous mode.
Figure 31-12 illustrates a character reception in synchronous mode.
Figure 31-12. Synchronous Mode Character Reception
Sampling
Clock (x16)
RXD
Start
Detection
Sampling
Baud Rate
Clock
RXD
Start
Rejection
Sampling
12345678
123456701234
123456789 10111213141516D0
Sampling
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Parity
Bit
Stop
Bit
Example: 8-bit, Parity Enabled
Baud Rate
Clock
Start
Detection
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
16
samples
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Start
Sampling
Parity Bit
Stop Bit
Example: 8-bit, Parity Enabled 1 Stop
Baud Rate
Clock
372
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.3.4 Receiver Operations
When a character reception is completed, it is transferred to the Receive Holding Register (US_RHR) and the
RXRDY bit in the Status Register (US_CSR) rises. If a character is completed while the RXRDY is set, the OVRE
(Overrun Error) bit is set. The last character is transferred into US_RHR and overwrites the previous one. The
OVRE bit is cleared by writing the Control Register (US_CR) with the RSTSTA (Reset Status) bit at 1.
Figure 31-13. Receiver Status
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
Write
US_CR
RXRDY
OVRE
D0 D1 D2 D3 D4 D5 D6 D7
Start
Bit
Parity
Bit
Stop
Bit
RSTSTA = 1
Read
US_RHR
373
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.3.5 Parity
The USART supports five parity modes selected by programming the PAR field in the Mode Register (US_MR).
The PAR field also enables the Multidrop mode, see “Multidrop Mode” on page 374. Even and odd parity bit gener-
ation and error detection are supported.
If even parity is selected, the parity generator of the transmitter drives the parity bit at 0 if a number of 1s in the
character data bit is even, and at 1 if the number of 1s is odd. Accordingly, the receiver parity checker counts the
number of received 1s and reports a parity error if the sampled parity bit does not correspond. If odd parity is
selected, the parity generator of the transmitter drives the parity bit at 1 if a number of 1s in the character data bit is
even, and at 0 if the number of 1s is odd. Accordingly, the receiver parity checker counts the number of received 1s
and reports a parity error if the sampled parity bit does not correspond. If the mark parity is used, the parity gener-
ator of the transmitter drives the parity bit at 1 for all characters. The receiver parity checker reports an error if the
parity bit is sampled at 0. If the space parity is used, the parity generator of the transmitter drives the parity bit at 0
for all characters. The receiver parity checker reports an error if the parity bit is sampled at 1. If parity is disabled,
the transmitter does not generate any parity bit and the receiver does not report any parity error.
Table 31-6 shows an example of the parity bit for the character 0x41 (character ASCII “A”) depending on the con-
figuration of the USART. Because there are two bits at 1, 1 bit is added when a parity is odd, or 0 is added when a
parity is even.
When the receiver detects a parity error, it sets the PARE (Parity Error) bit in the Channel Status Register
(US_CSR). The PARE bit can be cleared by writing the Control Register (US_CR) with the RSTSTA bit at 1. Figure
31-14 illustrates the parity bit status setting and clearing.
Figure 31-14. Parity Error
Table 31-6. Parity Bit Examples
Character Hexa Binary Parity Bit Parity Mode
A 0x41 0100 0001 1 Odd
A 0x41 0100 0001 0 Even
A 0x41 0100 0001 1 Mark
A 0x41 0100 0001 0 Space
A 0x41 0100 0001 None None
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Start
Bit
Bad
Parity
Bit
Stop
Bit
Baud Rate
Clock
Write
US_CR
PARE
RXRDY
RSTSTA = 1
374
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.3.6 Multidrop Mode
If the PAR field in the Mode Register (US_MR) is programmed to the value 0x6 or 0x07, the USART runs in Multi-
drop Mode. This mode differentiates the data characters and the address characters. Data is transmitted with the
parity bit at 0 and addresses are transmitted with the parity bit at 1.
If the USART is configured in multidrop mode, the receiver sets the PARE parity error bit when the parity bit is high
and the transmitter is able to send a character with the parity bit high when the Control Register is written with the
SENDA bit at 1.
To handle parity error, the PARE bit is cleared when the Control Register is written with the bit RSTSTA at 1.
The transmitter sends an address byte (parity bit set) when SENDA is written to US_CR. In this case, the next byte
written to US_THR is transmitted as an address. Any character written in US_THR without having written the com-
mand SENDA is transmitted normally with the parity at 0.
31.6.3.7 Transmitter Timeguard
The timeguard feature enables the USART interface with slow remote devices.
The timeguard function enables the transmitter to insert an idle state on the TXD line between two characters. This
idle state actually acts as a long stop bit.
The duration of the idle state is programmed in the TG field of the Transmitter Timeguard Register (US_TTGR).
When this field is programmed at zero no timeguard is generated. Otherwise, the transmitter holds a high level on
TXD after each transmitted byte during the number of bit periods programmed in TG in addition to the number of
stop bits.
As illustrated in Figure 31-15, the behavior of TXRDY and TXEMPTY status bits is modified by the programming of
a timeguard. TXRDY rises only when the start bit of the next character is sent, and thus remains at 0 during the
timeguard transmission if a character has been written in US_THR. TXEMPTY remains low until the timeguard
transmission is completed as the timeguard is part of the current character being transmitted.
Figure 31-15. Timeguard Operations
D0 D1 D2 D3 D4 D5 D6 D7
TXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
Start
Bit
TG = 4
Write
US_THR
D0 D1 D2 D3 D4 D5 D6 D7 Parity
Bit
Stop
Bit
TXRDY
TXEMPTY
TG = 4
375
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Table 31-7 indicates the maximum length of a timeguard period that the transmitter can handle in relation to the
function of the Baud Rate.
31.6.3.8 Receiver Time-out
The Receiver Time-out provides support in handling variable-length frames. This feature detects an idle condition
on the RXD line. When a time-out is detected, the bit TIMEOUT in the Channel Status Register (US_CSR) rises
and can generate an interrupt, thus indicating to the driver an end of frame.
The time-out delay period (during which the receiver waits for a new character) is programmed in the TO field of
the Receiver Time-out Register (US_RTOR). If the TO field is programmed at 0, the Receiver Time-out is disabled
and no time-out is detected. The TIMEOUT bit in US_CSR remains at 0. Otherwise, the receiver loads a 16-bit
counter with the value programmed in TO. This counter is decremented at each bit period and reloaded each time
a new character is received. If the counter reaches 0, the TIMEOUT bit in the Status Register rises. Then, the user
can either:
• Stop the counter clock until a new character is received. This is performed by writing the Control Register
(US_CR) with the STTTO (Start Time-out) bit at 1. In this case, the idle state on RXD before a new character is
received will not provide a time-out. This prevents having to handle an interrupt before a character is received
and allows waiting for the next idle state on RXD after a frame is received.
• Obtain an interrupt while no character is received. This is performed by writing US_CR with the RETTO (Reload
and Start Time-out) bit at 1. If RETTO is performed, the counter starts counting down immediately from the
value TO. This enables generation of a periodic interrupt so that a user time-out can be handled, for example
when no key is pressed on a keyboard.
If STTTO is performed, the counter clock is stopped until a first character is received. The idle state on RXD before
the start of the frame does not provide a time-out. This prevents having to obtain a periodic interrupt and enables a
wait of the end of frame when the idle state on RXD is detected.
If RETTO is performed, the counter starts counting down immediately from the value TO. This enables generation
of a periodic interrupt so that a user time-out can be handled, for example when no key is pressed on a keyboard.
Figure 31-16 shows the block diagram of the Receiver Time-out feature.
Table 31-7. Maximum Timeguard Length Depending on Baud Rate
Baud Rate Bit time Timeguard
Bit/sec µs ms
1 200 833 212.50
9 600 104 26.56
14400 69.4 17.71
19200 52.1 13.28
28800 34.7 8.85
33400 29.9 7.63
56000 17.9 4.55
57600 17.4 4.43
115200 8.7 2.21
376
SAM7S Series [DATASHEET]
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Figure 31-16. Receiver Time-out Block Diagram
Table 31-8 gives the maximum time-out period for some standard baud rates.
31.6.3.9 Framing Error
The receiver is capable of detecting framing errors. A framing error happens when the stop bit of a received char-
acter is detected at level 0. This can occur if the receiver and the transmitter are fully desynchronized.
A framing error is reported on the FRAME bit of the Channel Status Register (US_CSR). The FRAME bit is
asserted in the middle of the stop bit as soon as the framing error is detected. It is cleared by writing the Control
Register (US_CR) with the RSTSTA bit at 1.
Table 31-8. Maximum Time-out Period
Baud Rate Bit Time Time-out
bit/sec µs ms
600 1 667 109 225
1 200 833 54 613
2 400 417 27 306
4 800 208 13 653
9 600 104 6 827
14400 69 4 551
19200 52 3 413
28800 35 2 276
33400 30 1 962
56000 18 1 170
57600 17 1 138
200000 5 328
16-bit Time-out
Counter
0
TO
TIMEOUT
Baud Rate
Clock
=
Character
Received
RETTO
Load
Clock
16-bit
Value
STTTO
DQ
1
Clear
377
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-17. Framing Error Status
31.6.3.10 Transmit Break
The user can request the transmitter to generate a break condition on the TXD line. A break condition drives the
TXD line low during at least one complete character. It appears the same as a 0x00 character sent with the parity
and the stop bits at 0. However, the transmitter holds the TXD line at least during one character until the user
requests the break condition to be removed.
A break is transmitted by writing the Control Register (US_CR) with the STTBRK bit at 1. This can be performed at
any time, either while the transmitter is empty (no character in either the Shift Register or in US_THR) or when a
character is being transmitted. If a break is requested while a character is being shifted out, the character is first
completed before the TXD line is held low.
Once STTBRK command is requested further STTBRK commands are ignored until the end of the break is
completed.
The break condition is removed by writing US_CR with the STPBRK bit at 1. If the STPBRK is requested before the
end of the minimum break duration (one character, including start, data, parity and stop bits), the transmitter
ensures that the break condition completes.
The transmitter considers the break as though it is a character, i.e. the STTBRK and STPBRK commands are
taken into account only if the TXRDY bit in US_CSR is at 1 and the start of the break condition clears the TXRDY
and TXEMPTY bits as if a character is processed.
Writing US_CR with the both STTBRK and STPBRK bits at 1 can lead to an unpredictable result. All STPBRK
commands requested without a previous STTBRK command are ignored. A byte written into the Transmit Holding
Register while a break is pending, but not started, is ignored.
After the break condition, the transmitter returns the TXD line to 1 for a minimum of 12 bit times. Thus, the transmit-
ter ensures that the remote receiver detects correctly the end of break and the start of the next character. If the
timeguard is programmed with a value higher than 12, the TXD line is held high for the timeguard period.
After holding the TXD line for this period, the transmitter resumes normal operations.
Figure 31-18 illustrates the effect of both the Start Break (STTBRK) and Stop Break (STPBRK) commands on the
TXD line.
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
Write
US_CR
FRAME
RXRDY
RSTSTA = 1
378
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-18. Break Transmission
31.6.3.11 Receive Break
The receiver detects a break condition when all data, parity and stop bits are low. This corresponds to detecting a
framing error with data at 0x00, but FRAME remains low.
When the low stop bit is detected, the receiver asserts the RXBRK bit in US_CSR. This bit may be cleared by writ-
ing the Control Register (US_CR) with the bit RSTSTA at 1.
An end of receive break is detected by a high level for at least 2/16 of a bit period in asynchronous operating mode
or one sample at high level in synchronous operating mode. The end of break detection also asserts the RXBRK
bit.
31.6.3.12 Hardware Handshaking
The USART features a hardware handshaking out-of-band flow control. The RTS and CTS pins are used to con-
nect with the remote device, as shown in Figure 31-19.
Figure 31-19. Connection with a Remote Device for Hardware Handshaking
Setting the USART to operate with hardware handshaking is performed by writing the USART_MODE field in the
Mode Register (US_MR) to the value 0x2.
The USART behavior when hardware handshaking is enabled is the same as the behavior in standard synchro-
nous or asynchronous mode, except that the receiver drives the RTS pin as described below and the level on the
CTS pin modifies the behavior of the transmitter as described below. Using this mode requires using the PDC
channel for reception. The transmitter can handle hardware handshaking in any case.
Figure 31-20 shows how the receiver operates if hardware handshaking is enabled. The RTS pin is driven high if
the receiver is disabled and if the status RXBUFF (Receive Buffer Full) coming from the PDC channel is high. Nor-
mally, the remote device does not start transmitting while its CTS pin (driven by RTS) is high. As soon as the
D0 D1 D2 D3 D4 D5 D6 D7
TXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
Write
US_CR
TXRDY
TXEMPTY
STPBRK = 1
STTBRK = 1
Break Transmission End of Break
USART
TXD
CTS
Remote
Device
RXD
TXDRXD
RTS
RTS
CTS
379
SAM7S Series [DATASHEET]
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Receiver is enabled, the RTS falls, indicating to the remote device that it can start transmitting. Defining a new buf-
fer to the PDC clears the status bit RXBUFF and, as a result, asserts the pin RTS low.
Figure 31-20. Receiver Behavior when Operating with Hardware Handshaking
Figure 31-21 shows how the transmitter operates if hardware handshaking is enabled. The CTS pin disables the
transmitter. If a character is being processing, the transmitter is disabled only after the completion of the current
character and transmission of the next character happens as soon as the pin CTS falls.
Figure 31-21. Transmitter Behavior when Operating with Hardware Handshaking
31.6.4 ISO7816 Mode
The USART features an ISO7816-compatible operating mode. This mode permits interfacing with smart cards and
Security Access Modules (SAM) communicating through an ISO7816 link. Both T = 0 and T = 1 protocols defined
by the ISO7816 specification are supported.
Setting the USART in ISO7816 mode is performed by writing the USART_MODE field in the Mode Register
(US_MR) to the value 0x4 for protocol T = 0 and to the value 0x5 for protocol T = 1.
31.6.4.1 ISO7816 Mode Overview
The ISO7816 is a half duplex communication on only one bidirectional line. The baud rate is determined by a divi-
sion of the clock provided to the remote device (see “Baud Rate Generator” on page 364).
The USART connects to a smart card as shown in Figure 31-22. The TXD line becomes bidirectional and the Baud
Rate Generator feeds the ISO7816 clock on the SCK pin. As the TXD pin becomes bidirectional, its output remains
driven by the output of the transmitter but only when the transmitter is active while its input is directed to the input
of the receiver. The USART is considered as the master of the communication as it generates the clock.
Figure 31-22. Connection of a Smart Card to the USART
When operating in ISO7816, either in T = 0 or T = 1 modes, the character format is fixed. The configuration is 8
data bits, even parity and 1 or 2 stop bits, regardless of the values programmed in the CHRL, MODE9, PAR and
RTS
RXBUFF
Write
US_CR
RXEN = 1
RXD
RXDIS = 1
CTS
TXD
Smart
Card
SCK CLK
TXD I/O
USART
380
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
CHMODE fields. MSBF can be used to transmit LSB or MSB first. Parity Bit (PAR) can be used to transmit in nor-
mal or inverse mode. Refer to “USART Mode Register” on page 390 and “PAR: Parity Type” on page 392.
The USART cannot operate concurrently in both receiver and transmitter modes as the communication is unidirec-
tional at a time. It has to be configured according to the required mode by enabling or disabling either the receiver
or the transmitter as desired. Enabling both the receiver and the transmitter at the same time in ISO7816 mode
may lead to unpredictable results.
The ISO7816 specification defines an inverse transmission format. Data bits of the character must be transmitted
on the I/O line at their negative value. The USART does not support this format and the user has to perform an
exclusive OR on the data before writing it in the Transmit Holding Register (US_THR) or after reading it in the
Receive Holding Register (US_RHR).
31.6.4.2 Protocol T = 0
In T = 0 protocol, a character is made up of one start bit, eight data bits, one parity bit and one guard time, which
lasts two bit times. The transmitter shifts out the bits and does not drive the I/O line during the guard time.
If no parity error is detected, the I/O line remains at 1 during the guard time and the transmitter can continue with
the transmission of the next character, as shown in Figure 31-23.
If a parity error is detected by the receiver, it drives the I/O line at 0 during the guard time, as shown in Figure 31-
24. This error bit is also named NACK, for Non Acknowledge. In this case, the character lasts 1 bit time more, as
the guard time length is the same and is added to the error bit time which lasts 1 bit time.
When the USART is the receiver and it detects an error, it does not load the erroneous character in the Receive
Holding Register (US_RHR). It appropriately sets the PARE bit in the Status Register (US_SR) so that the software
can handle the error.
Figure 31-23. T = 0 Protocol without Parity Error
Figure 31-24. T = 0 Protocol with Parity Error
31.6.4.3 Receive Error Counter
The USART receiver also records the total number of errors. This can be read in the Number of Error (US_NER)
register. The NB_ERRORS field can record up to 255 errors. Reading US_NER automatically clears the
NB_ERRORS field.
D0 D1 D2 D3 D4 D5 D6 D7
RXD
Parity
Bit
Baud Rate
Clock
Start
Bit
Guard
Time 1
Next
Start
Bit
Guard
Time 2
D0 D1 D2 D3 D4 D5 D6 D7
I/O
Parity
Bit
Baud Rate
Clock
Start
Bit
Guard
Time 1
Start
Bit
Guard
Time 2
D0 D1
Error
Repetition
381
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.4.4 Receive NACK Inhibit
The USART can also be configured to inhibit an error. This can be achieved by setting the INACK bit in the Mode
Register (US_MR). If INACK is at 1, no error signal is driven on the I/O line even if a parity bit is detected, but the
INACK bit is set in the Status Register (US_SR). The INACK bit can be cleared by writing the Control Register
(US_CR) with the RSTNACK bit at 1.
Moreover, if INACK is set, the erroneous received character is stored in the Receive Holding Register, as if no
error occurred. However, the RXRDY bit does not raise.
31.6.4.5 Transmit Character Repetition
When the USART is transmitting a character and gets a NACK, it can automatically repeat the character before
moving on to the next one. Repetition is enabled by writing the MAX_ITERATION field in the Mode Register
(US_MR) at a value higher than 0. Each character can be transmitted up to eight times; the first transmission plus
seven repetitions.
If MAX_ITERATION does not equal zero, the USART repeats the character as many times as the value loaded in
MAX_ITERATION.
When the USART repetition number reaches MAX_ITERATION, the ITERATION bit is set in the Channel Status
Register (US_CSR). If the repetition of the character is acknowledged by the receiver, the repetitions are stopped
and the iteration counter is cleared.
The ITERATION bit in US_CSR can be cleared by writing the Control Register with the RSIT bit at 1.
31.6.4.6 Disable Successive Receive NACK
The receiver can limit the number of successive NACKs sent back to the remote transmitter. This is programmed
by setting the bit DSNACK in the Mode Register (US_MR). The maximum number of NACK transmitted is pro-
grammed in the MAX_ITERATION field. As soon as MAX_ITERATION is reached, the character is considered as
correct, an acknowledge is sent on the line and the ITERATION bit in the Channel Status Register is set.
31.6.4.7 Protocol T = 1
When operating in ISO7816 protocol T = 1, the transmission is similar to an asynchronous format with only one
stop bit. The parity is generated when transmitting and checked when receiving. Parity error detection sets the
PARE bit in the Channel Status Register (US_CSR).
31.6.5 IrDA Mode
The USART features an IrDA mode supplying half-duplex point-to-point wireless communication. It embeds the
modulator and demodulator which allows a glueless connection to the infrared transceivers, as shown in Figure 31-
25. The modulator and demodulator are compliant with the IrDA specification version 1.1 and support data transfer
speeds ranging from 2.4 Kb/s to 115.2 Kb/s.
The USART IrDA mode is enabled by setting the USART_MODE field in the Mode Register (US_MR) to the value
0x8. The IrDA Filter Register (US_IF) allows configuring the demodulator filter. The USART transmitter and
receiver operate in a normal asynchronous mode and all parameters are accessible. Note that the modulator and
the demodulator are activated.
382
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-25. Connection to IrDA Transceivers
The receiver and the transmitter must be enabled or disabled according to the direction of the transmission to be
managed.
To receive IrDA signals, the following needs to be done:
• Disable TX and Enable RX
• Configure the TXD pin as PIO and set it as an output at 0 (to avoid LED emission). Disable the internal pull-up
(better for power consumption).
• Receive data
31.6.5.1 IrDA Modulation
For baud rates up to and including 115.2 Kbits/sec, the RZI modulation scheme is used. “0” is represented by a
light pulse of 3/16th of a bit time. Some examples of signal pulse duration are shown in Table 31-9.
Figure 31-26 shows an example of character transmission.
IrDA
Transceivers
RXD RX
TXD
TX
USART
Demodulator
Modulator
Receiver
Transmitter
Table 31-9. IrDA Pulse Duration
Baud Rate Pulse Duration (3/16)
2.4 Kb/s 78.13 µs
9.6 Kb/s 19.53 µs
19.2 Kb/s 9.77 µs
38.4 Kb/s 4.88 µs
57.6 Kb/s 3.26 µs
115.2 Kb/s 1.63 µs
383
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 31-26. IrDA Modulation
31.6.5.2 IrDA Baud Rate
Table 31-10 gives some examples of CD values, baud rate error and pulse duration. Note that the requirement on
the maximum acceptable error of ±1.87% must be met.
Bit Period Bit Period
3
16
Start
Bit
Data Bits Stop
Bit
00
000
111 1
1
Transmitter
Output
TXD
Table 31-10. IrDA Baud Rate Error
Peripheral Clock Baud Rate CD Baud Rate Error Pulse Time
3 686 400 115 200 2 0.00% 1.63
20 000 000 115 200 11 1.38% 1.63
32 768 000 115 200 18 1.25% 1.63
40 000 000 115 200 22 1.38% 1.63
3 686 400 57 600 4 0.00% 3.26
20 000 000 57 600 22 1.38% 3.26
32 768 000 57 600 36 1.25% 3.26
40 000 000 57 600 43 0.93% 3.26
3 686 400 38 400 6 0.00% 4.88
20 000 000 38 400 33 1.38% 4.88
32 768 000 38 400 53 0.63% 4.88
40 000 000 38 400 65 0.16% 4.88
3 686 400 19 200 12 0.00% 9.77
20 000 000 19 200 65 0.16% 9.77
32 768 000 19 200 107 0.31% 9.77
40 000 000 19 200 130 0.16% 9.77
3 686 400 9 600 24 0.00% 19.53
20 000 000 9 600 130 0.16% 19.53
32 768 000 9 600 213 0.16% 19.53
40 000 000 9 600 260 0.16% 19.53
3 686 400 2 400 96 0.00% 78.13
20 000 000 2 400 521 0.03% 78.13
32 768 000 2 400 853 0.04% 78.13
384
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.5.3 IrDA Demodulator
The demodulator is based on the IrDA Receive filter comprised of an 8-bit down counter which is loaded with the
value programmed in US_IF. When a falling edge is detected on the RXD pin, the Filter Counter starts counting
down at the Master Clock (MCK) speed. If a rising edge is detected on the RXD pin, the counter stops and is
reloaded with US_IF. If no rising edge is detected when the counter reaches 0, the input of the receiver is driven
low during one bit time.
Figure 31-27 illustrates the operations of the IrDA demodulator.
Figure 31-27. IrDA Demodulator Operations
As the IrDA mode uses the same logic as the ISO7816, note that the FI_DI_RATIO field in US_FIDI must be set to
a value higher than 0 in order to assure IrDA communications operate correctly.
MCK
RXD
Receiver
Input
Pulse
Rejected
65432 61
65432 0
Pulse
Accepted
Counter
Value
385
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.6 RS485 Mode
The USART features the RS485 mode to enable line driver control. While operating in RS485 mode, the USART
behaves as though in asynchronous or synchronous mode and configuration of all the parameters is possible. The
difference is that the RTS pin is driven high when the transmitter is operating. The behavior of the RTS pin is con-
trolled by the TXEMPTY bit. A typical connection of the USART to a RS485 bus is shown in Figure 31-28.
Figure 31-28. Typical Connection to a RS485 Bus
The USART is set in RS485 mode by programming the USART_MODE field in the Mode Register (US_MR) to the
value 0x1.
The RTS pin is at a level inverse to the TXEMPTY bit. Significantly, the RTS pin remains high when a timeguard is
programmed so that the line can remain driven after the last character completion. Figure 31-29 gives an example
of the RTS waveform during a character transmission when the timeguard is enabled.
Figure 31-29. Example of RTS Drive with Timeguard
USART
RTS
TXD
RXD
Differential
Bus
D0 D1 D2 D3 D4 D5 D6 D7
TXD
Start
Bit
Parity
Bit
Stop
Bit
Baud Rate
Clock
TG = 4
Write
US_THR
TXRDY
TXEMPTY
RTS
386
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.7 SAM7S512/256/128/64/321/161 Modem Mode
The USART features modem mode, which enables control of the signals: DTR (Data Terminal Ready), DSR (Data
Set Ready), RTS (Request to Send), CTS (Clear to Send), DCD (Data Carrier Detect) and RI (Ring Indicator).
While operating in modem mode, the USART behaves as a DTE (Data Terminal Equipment) as it drives DTR and
RTS and can detect level change on DSR, DCD, CTS and RI.
Setting the USART in modem mode is performed by writing the USART_MODE field in the Mode Register
(US_MR) to the value 0x3. While operating in modem mode the USART behaves as though in asynchronous mode
and all the parameter configurations are available.
Table 31-11 gives the correspondence of the USART signals with modem connection standards.
The control of the DTR output pin is performed by writing the Control Register (US_CR) with the DTRDIS and
DTREN bits respectively at 1. The disable command forces the corresponding pin to its inactive level, i.e. high. The
enable command forces the corresponding pin to its active level, i.e. low. RTS output pin is automatically controlled
in this mode
The level changes are detected on the RI, DSR, DCD and CTS pins. If an input change is detected, the RIIC,
DSRIC, DCDIC and CTSIC bits in the Channel Status Register (US_CSR) are set respectively and can trigger an
interrupt. The status is automatically cleared when US_CSR is read. Furthermore, the CTS automatically disables
the transmitter when it is detected at its inactive state. If a character is being transmitted when the CTS rises, the
character transmission is completed before the transmitter is actually disabled.
31.6.8 Test Modes
The USART can be programmed to operate in three different test modes. The internal loopback capability allows
on-board diagnostics. In the loopback mode the USART interface pins are disconnected or not and reconfigured
for loopback internally or externally.
31.6.8.1 Normal Mode
Normal mode connects the RXD pin on the receiver input and the transmitter output on the TXD pin.
Figure 31-30. Normal Mode Configuration
Table 31-11. Circuit References
USART Pin V24 CCITT Direction
TXD 2 103 From terminal to modem
RTS 4 105 From terminal to modem
DTR 20 108.2 From terminal to modem
RXD 3 104 From modem to terminal
CTS 5 106 From terminal to modem
DSR 6 107 From terminal to modem
DCD 8 109 From terminal to modem
RI 22 125 From terminal to modem
Receiver
Transmitter
RXD
TXD
387
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.6.8.2 Automatic Echo Mode
Automatic echo mode allows bit-by-bit retransmission. When a bit is received on the RXD pin, it is sent to the TXD
pin, as shown in Figure 31-31. Programming the transmitter has no effect on the TXD pin. The RXD pin is still con-
nected to the receiver input, thus the receiver remains active.
Figure 31-31. Automatic Echo Mode Configuration
31.6.8.3 Local Loopback Mode
Local loopback mode connects the output of the transmitter directly to the input of the receiver, as shown in Figure
31-32. The TXD and RXD pins are not used. The RXD pin has no effect on the receiver and the TXD pin is contin-
uously driven high, as in idle state.
Figure 31-32. Local Loopback Mode Configuration
31.6.8.4 Remote Loopback Mode
Remote loopback mode directly connects the RXD pin to the TXD pin, as shown in Figure 31-33. The transmitter
and the receiver are disabled and have no effect. This mode allows bit-by-bit retransmission.
Figure 31-33. Remote Loopback Mode Configuration
Receiver
Transmitter
RXD
TXD
Receiver
Transmitter
RXD
TXD
1
Receiver
Transmitter
RXD
TXD
1
388
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7 Universal Synchronous Asynchronous Receiver Transmitter (USART) User Interface
Table 31-12. Memory Map
Offset Register Name Access Reset
0x0000 Control Register US_CR Write-only –
0x0004 Mode Register US_MR Read-write –
0x0008 Interrupt Enable Register US_IER Write-only –
0x000C Interrupt Disable Register US_IDR Write-only –
0x0010 Interrupt Mask Register US_IMR Read-only 0x0
0x0014 Channel Status Register US_CSR Read-only –
0x0018 Receiver Holding Register US_RHR Read-only 0x0
0x001C Transmitter Holding Register US_THR Write-only –
0x0020 Baud Rate Generator Register US_BRGR Read-write 0x0
0x0024 Receiver Time-out Register US_RTOR Read-write 0x0
0x0028 Transmitter Timeguard Register US_TTGR Read-write 0x0
0x2C - 0x3C Reserved – – –
0x0040 FI DI Ratio Register US_FIDI Read-write 0x174
0x0044 Number of Errors Register US_NER Read-only –
0x0048 Reserved – – –
0x004C IrDA Filter Register US_IF Read-write 0x0
0x5C - 0xFC Reserved – – –
0x100 - 0x128 Reserved for PDC Registers – – –
389
SAM7S Series [DATASHEET]
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31.7.1 USART Control Register
Name: US_CR
Access Type: Write-only
Note: 1. DTRDIS and DTREN do not pertain to the SAM7S32/16.
• RSTRX: Reset Receiver
0: No effect.
1: Resets the receiver.
• RSTTX: Reset Transmitter
0: No effect.
1: Resets the transmitter.
• RXEN: Receiver Enable
0: No effect.
1: Enables the receiver, if RXDIS is 0.
• RXDIS: Receiver Disable
0: No effect.
1: Disables the receiver.
• TXEN: Transmitter Enable
0: No effect.
1: Enables the transmitter if TXDIS is 0.
• TXDIS: Transmitter Disable
0: No effect.
1: Disables the transmitter.
• RSTSTA: Reset Status Bits
0: No effect.
1: Resets the status bits PARE, FRAME, OVRE, and RXBRK in US_CSR.
• STTBRK: Start Break
0: No effect.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––RTSDISRTSENDTRDIS
(1) DTREN(1)
15 14 13 12 11 10 9 8
RETTO RSTNACK RSTIT SENDA STTTO STPBRK STTBRK RSTSTA
76543210
TXDIS TXEN RXDIS RXEN RSTTX RSTRX – –
390
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
1: Starts transmission of a break after the characters present in US_THR and the Transmit Shift Register have been trans-
mitted. No effect if a break is already being transmitted.
• STPBRK: Stop Break
0: No effect.
1: Stops transmission of the break after a minimum of one character length and transmits a high level during 12-bit periods.
No effect if no break is being transmitted.
• STTTO: Start Time-out
0: No effect.
1: Starts waiting for a character before clocking the time-out counter. Resets the status bit TIMEOUT in US_CSR.
• SENDA: Send Address
0: No effect.
1: In Multidrop Mode only, the next character written to the US_THR is sent with the address bit set.
• RSTIT: Reset Iterations
0: No effect.
1: Resets ITERATION in US_CSR. No effect if the ISO7816 is not enabled.
• RSTNACK: Reset Non Acknowledge
0: No effect
1: Resets NACK in US_CSR.
• RETTO: Rearm Time-out
0: No effect
1: Restart Time-out
• DTREN: Data Terminal Ready Enable
0: No effect.
1: Drives the pin DTR at 0.
• DTRDIS: Data Terminal Ready Disable
0: No effect.
1: Drives the pin DTR to 1.
• RTSEN: Request to Send Enable
0: No effect.
1: Drives the pin RTS to 0.
• RTSDIS: Request to Send Disable
0: No effect.
1: Drives the pin RTS to 1.
31.7.2 USART Mode Register
Name: US_MR
391
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Access Type: Read-write
• USART_MODE
• USCLKS: Clock Selection
• CHRL: Character Length.
• SYNC: Synchronous Mode Select
0: USART operates in Asynchronous Mode.
31 30 29 28 27 26 25 24
– – – FILTER – MAX_ITERATION
23 22 21 20 19 18 17 16
– – DSNACK INACK OVER CLKO MODE9 MSBF
15 14 13 12 11 10 9 8
CHMODE NBSTOP PAR SYNC
76543210
CHRL USCLKS USART_MODE
USART_MODE Mode of the USART
0000Normal
0001RS485
0 0 1 0 Hardware Handshaking
0 0 1 1 Modem (Reserved on SAM7S32/16)
0 1 0 0 IS07816 Protocol: T = 0
0101Reserved
0 1 1 0 IS07816 Protocol: T = 1
0111Reserved
1000IrDA
11xxReserved
USCLKS Selected Clock
00MCK
0 1 MCK/DIV (DIV = 8)
10Reserved
11SCK
CHRL Character Length
0 0 5 bits
0 1 6 bits
1 0 7 bits
1 1 8 bits
392
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
1: USART operates in Synchronous Mode.
• PAR: Parity Type
• NBSTOP: Number of Stop Bits
• CHMODE: Channel Mode
• MSBF: Bit Order
0: Least Significant Bit is sent/received first.
1: Most Significant Bit is sent/received first.
• MODE9: 9-bit Character Length
0: CHRL defines character length.
1: 9-bit character length.
• CLKO: Clock Output Select
0: The USART does not drive the SCK pin.
1: The USART drives the SCK pin if USCLKS does not select the external clock SCK.
• OVER: Oversampling Mode
0: 16x Oversampling.
1: 8x Oversampling.
PAR Parity Type
0 0 0 Even parity
001Odd parity
0 1 0 Parity forced to 0 (Space)
0 1 1 Parity forced to 1 (Mark)
1 0 x No parity
1 1 x Multidrop mode
NBSTOP Asynchronous (SYNC = 0) Synchronous (SYNC = 1)
0 0 1 stop bit 1 stop bit
0 1 1.5 stop bits Reserved
1 0 2 stop bits 2 stop bits
1 1 Reserved Reserved
CHMODE Mode Description
0 0 Normal Mode
0 1 Automatic Echo. Receiver input is connected to the TXD pin.
1 0 Local Loopback. Transmitter output is connected to the Receiver Input..
1 1 Remote Loopback. RXD pin is internally connected to the TXD pin.
393
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• INACK: Inhibit Non Acknowledge
0: The NACK is generated.
1: The NACK is not generated.
• DSNACK: Disable Successive NACK
0: NACK is sent on the ISO line as soon as a parity error occurs in the received character (unless INACK is set).
1: Successive parity errors are counted up to the value specified in the MAX_ITERATION field. These parity errors gener-
ate a NACK on the ISO line. As soon as this value is reached, no additional NACK is sent on the ISO line. The flag
ITERATION is asserted.
• MAX_ITERATION
Defines the maximum number of iterations in mode ISO7816, protocol T= 0.
• FILTER: Infrared Receive Line Filter
0: The USART does not filter the receive line.
1: The USART filters the receive line using a three-sample filter (1/16-bit clock) (2 over 3 majority).
394
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.3 USART Interrupt Enable Register
Name: US_IER
Access Type: Write-only
Note: 1. DCDIC, DSRIC and RIIC do not pertain to the SAM7S32/16.
• RXRDY: RXRDY Interrupt Enable
• TXRDY: TXRDY Interrupt Enable
• RXBRK: Receiver Break Interrupt Enable
• ENDRX: End of Receive Transfer Interrupt Enable
• ENDTX: End of Transmit Interrupt Enable
• OVRE: Overrun Error Interrupt Enable
• FRAME: Framing Error Interrupt Enable
• PARE: Parity Error Interrupt Enable
• TIMEOUT: Time-out Interrupt Enable
• TXEMPTY: TXEMPTY Interrupt Enable
• ITERATION: Iteration Interrupt Enable
• TXBUFE: Buffer Empty Interrupt Enable
• RXBUFF: Buffer Full Interrupt Enable
• NACK: Non Acknowledge Interrupt Enable
• RIIC: Ring Indicator Input Change Enable
• DSRIC: Data Set Ready Input Change Enable
• DCDIC: Data Carrier Detect Input Change Interrupt Enable
• CTSIC: Clear to Send Input Change Interrupt Enable
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––CTSICDCDIC (1) DSRIC
(1) RIIC
(1)
15 14 13 12 11 10 9 8
– – NACK RXBUFF TXBUFE ITERATION TXEMPTY TIMEOUT
76543210
PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY
395
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.4 USART Interrupt Disable Register
Name: US_IDR
Access Type: Write-only
Note: 1. DCDIC, DSRIC and RIIC do not pertain to the SAM7S32/16.
• RXRDY: RXRDY Interrupt Disable
• TXRDY: TXRDY Interrupt Disable
• RXBRK: Receiver Break Interrupt Disable
• ENDRX: End of Receive Transfer Interrupt Disable
• ENDTX: End of Transmit Interrupt Disable
• OVRE: Overrun Error Interrupt Disable
• FRAME: Framing Error Interrupt Disable
• PARE: Parity Error Interrupt Disable
• TIMEOUT: Time-out Interrupt Disable
• TXEMPTY: TXEMPTY Interrupt Disable
• ITERATION: Iteration Interrupt Disable
• TXBUFE: Buffer Empty Interrupt Disable
• RXBUFF: Buffer Full Interrupt Disable
• NACK: Non Acknowledge Interrupt Disable
• RIIC: Ring Indicator Input Change Disable
• DSRIC: Data Set Ready Input Change Disable
• DCDIC: Data Carrier Detect Input Change Interrupt Disable
• CTSIC: Clear to Send Input Change Interrupt Disable
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––CTSICDCDIC (1) DSRIC
(1) RIIC
(1)
15 14 13 12 11 10 9 8
– – NACK RXBUFF TXBUFE ITERATION TXEMPTY TIMEOUT
76543210
PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY
396
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.5 USART Interrupt Mask Register
Name: US_IMR
Access Type: Read-only
Note: 1. DCDIC, DSRIC and RIIC do not pertain to the SAM7S32/16.
• RXRDY: RXRDY Interrupt Mask
• TXRDY: TXRDY Interrupt Mask
• RXBRK: Receiver Break Interrupt Mask
• ENDRX: End of Receive Transfer Interrupt Mask
• ENDTX: End of Transmit Interrupt Mask
• OVRE: Overrun Error Interrupt Mask
• FRAME: Framing Error Interrupt Mask
• PARE: Parity Error Interrupt Mask
• TIMEOUT: Time-out Interrupt Mask
• TXEMPTY: TXEMPTY Interrupt Mask
• ITERATION: Iteration Interrupt Mask
• TXBUFE: Buffer Empty Interrupt Mask
• RXBUFF: Buffer Full Interrupt Mask
• NACK: Non Acknowledge Interrupt Mask
• RIIC: Ring Indicator Input Change Mask
• DSRIC: Data Set Ready Input Change Mask
• DCDIC: Data Carrier Detect Input Change Interrupt Mask
• CTSIC: Clear to Send Input Change Interrupt Mask
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––CTSICDCDIC (1) DSRIC(1) RIIC (1)
15 14 13 12 11 10 9 8
– – NACK RXBUFF TXBUFE ITERATION TXEMPTY TIMEOUT
76543210
PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY
397
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.6 USART Channel Status Register
Name: US_CSR
Access Type: Read-only
Note: 1. DCDIC, DSRIC and RIIC do not pertain to the SAM7S32/16.
• RXRDY: Receiver Ready
0: No complete character has been received since the last read of US_RHR or the receiver is disabled. If characters were
being received when the receiver was disabled, RXRDY changes to 1 when the receiver is enabled.
1: At least one complete character has been received and US_RHR has not yet been read.
• TXRDY: Transmitter Ready
0: A character is in the US_THR waiting to be transferred to the Transmit Shift Register, or an STTBRK command has been
requested, or the transmitter is disabled. As soon as the transmitter is enabled, TXRDY becomes 1.
1: There is no character in the US_THR.
• RXBRK: Break Received/End of Break
0: No Break received or End of Break detected since the last RSTSTA.
1: Break Received or End of Break detected since the last RSTSTA.
• ENDRX: End of Receiver Transfer
0: The End of Transfer signal from the Receive PDC channel is inactive.
1: The End of Transfer signal from the Receive PDC channel is active.
• ENDTX: End of Transmitter Transfer
0: The End of Transfer signal from the Transmit PDC channel is inactive.
1: The End of Transfer signal from the Transmit PDC channel is active.
• OVRE: Overrun Error
0: No overrun error has occurred since the last RSTSTA.
1: At least one overrun error has occurred since the last RSTSTA.
• FRAME: Framing Error
0: No stop bit has been detected low since the last RSTSTA.
1: At least one stop bit has been detected low since the last RSTSTA.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
CTS DCD DSR RI CTSIC DCDIC
(1) DSRIC
(1) RIIC
(1)
15 14 13 12 11 10 9 8
– – NACK RXBUFF TXBUFE ITERATION TXEMPTY TIMEOUT
76543210
PARE FRAME OVRE ENDTX ENDRX RXBRK TXRDY RXRDY
398
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• PARE: Parity Error
0: No parity error has been detected since the last RSTSTA.
1: At least one parity error has been detected since the last RSTSTA.
• TIMEOUT: Receiver Time-out
0: There has not been a time-out since the last Start Time-out command (STTTO in US_CR) or the Time-out Register is 0.
1: There has been a time-out since the last Start Time-out command (STTTO in US_CR).
• TXEMPTY: Transmitter Empty
0: There are characters in either US_THR or the Transmit Shift Register, or the transmitter is disabled.
1: There are no characters in US_THR, nor in the Transmit Shift Register.
• ITERATION: Max number of Repetitions Reached
0: Maximum number of repetitions has not been reached since the last RSIT.
1: Maximum number of repetitions has been reached since the last RSIT.
• TXBUFE: Transmission Buffer Empty
0: The signal Buffer Empty from the Transmit PDC channel is inactive.
1: The signal Buffer Empty from the Transmit PDC channel is active.
• RXBUFF: Reception Buffer Full
0: The signal Buffer Full from the Receive PDC channel is inactive.
1: The signal Buffer Full from the Receive PDC channel is active.
• NACK: Non Acknowledge
0: No Non Acknowledge has not been detected since the last RSTNACK.
1: At least one Non Acknowledge has been detected since the last RSTNACK.
• RIIC: Ring Indicator Input Change Flag
0: No input change has been detected on the RI pin since the last read of US_CSR.
1: At least one input change has been detected on the RI pin since the last read of US_CSR.
• DSRIC: Data Set Ready Input Change Flag
0: No input change has been detected on the DSR pin since the last read of US_CSR.
1: At least one input change has been detected on the DSR pin since the last read of US_CSR.
• DCDIC: Data Carrier Detect Input Change Flag
0: No input change has been detected on the DCD pin since the last read of US_CSR.
1: At least one input change has been detected on the DCD pin since the last read of US_CSR.
• CTSIC: Clear to Send Input Change Flag
0: No input change has been detected on the CTS pin since the last read of US_CSR.
1: At least one input change has been detected on the CTS pin since the last read of US_CSR.
399
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• RI: Image of RI Input
0: RI is at 0.
1: RI is at 1.
• DSR: Image of DSR Input
0: DSR is at 0
1: DSR is at 1.
• DCD: Image of DCD Input
0: DCD is at 0.
1: DCD is at 1.
• CTS: Image of CTS Input
0: CTS is at 0.
1: CTS is at 1.
400
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.7 USART Receive Holding Register
Name: US_RHR
Access Type: Read-only
• RXCHR: Received Character
Last character received if RXRDY is set.
• RXSYNH: Received Sync
0: Last Character received is a Data.
1: Last Character received is a Command.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
RXSYNH ––––––RXCHR
76543210
RXCHR
401
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.8 USART Transmit Holding Register
Name: US_THR
Access Type: Write-only
• TXCHR: Character to be Transmitted
Next character to be transmitted after the current character if TXRDY is not set.
• TXSYNH: Sync Field to be transmitted
0: The next character sent is encoded as a data. Start Frame Delimiter is DATA SYNC.
1: The next character sent is encoded as a command. Start Frame Delimiter is COMMAND SYNC.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
TXSYNH ––––––TXCHR
76543210
TXCHR
402
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.9 USART Baud Rate Generator Register
Name: US_BRGR
Access Type: Read-write
• CD: Clock Divider
• FP: Fractional Part
0: Fractional divider is disabled.
1 - 7: Baudrate resolution, defined by FP x 1/8.
Note: Fractional Part is not supported by SAM7S32 and SAM7S64.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––– FP
15 14 13 12 11 10 9 8
CD
76543210
CD
CD
USART_MODE ≠ ISO7816
USART_MODE =
ISO7816
SYNC = 0 SYNC = 1
OVER = 0 OVER = 1
0 Baud Rate Clock Disabled
1 to 65535 Baud Rate =
Selected Clock/16/CD
Baud Rate =
Selected Clock/8/CD
Baud Rate =
Selected Clock /CD
Baud Rate = Selected
Clock/CD/FI_DI_RATIO
403
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.10 USART Receiver Time-out Register
Name: US_RTOR
Access Type: Read-write
• TO: Time-out Value
0: The Receiver Time-out is disabled.
1 - 65535: The Receiver Time-out is enabled and the Time-out delay is TO x Bit Period.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
TO
76543210
TO
404
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.11 USART Transmitter Timeguard Register
Name: US_TTGR
Access Type: Read-write
• TG: Timeguard Value
0: The Transmitter Timeguard is disabled.
1 - 255: The Transmitter timeguard is enabled and the timeguard delay is TG x Bit Period.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
TG
405
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.12 USART FI DI RATIO Register
Name: US_FIDI
Access Type: Read-write
Reset Value : 0x174
• FI_DI_RATIO: FI Over DI Ratio Value
0: If ISO7816 mode is selected, the Baud Rate Generator generates no signal.
1 - 2047: If ISO7816 mode is selected, the Baud Rate is the clock provided on SCK divided by FI_DI_RATIO.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––– FI_DI_RATIO
76543210
FI_DI_RATIO
406
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.13 USART Number of Errors Register
Name: US_NER
Access Type: Read-only
• NB_ERRORS: Number of Errors
Total number of errors that occurred during an ISO7816 transfer. This register automatically clears when read.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
NB_ERRORS
407
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
31.7.14 USART IrDA FILTER Register
Name: US_IF
Access Type: Read-write
• IRDA_FILTER: IrDA Filter
Sets the filter of the IrDA demodulator.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
IRDA_FILTER
408
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
409
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32. Synchronous Serial Controller (SSC)
32.1 Description
The Atmel Synchronous Serial Controller (SSC) provides a synchronous communication link with external devices.
It supports many serial synchronous communication protocols generally used in audio and telecom applications
such as I2S, Short Frame Sync, Long Frame Sync, etc.
The SSC contains an independent receiver and transmitter and a common clock divider. The receiver and the
transmitter each interface with three signals: the TD/RD signal for data, the TK/RK signal for the clock and the
TF/RF signal for the Frame Sync. The transfers can be programmed to start automatically or on different events
detected on the Frame Sync signal.
The SSC’s high-level of programmability and its two dedicated PDC channels of up to 32 bits permit a continuous
high bit rate data transfer without processor intervention.
Featuring connection to two PDC channels, the SSC permits interfacing with low processor overhead to the
following:
• CODEC’s in master or slave mode
• DAC through dedicated serial interface, particularly I2S
• Magnetic card reader
32.2 Block Diagram
Figure 32-1. Block Diagram
SSC Interface PIO
PDC
APB Bridge
MCK
System
Bus
Peripheral
Bus
TF
TK
TD
RF
RK
RD
Interrupt Control
SSC Interrupt
PMC
410
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.3 Application Block Diagram
Figure 32-2. Application Block Diagram
32.4 Pin Name List
32.5 Product Dependencies
32.5.1 I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines.
Before using the SSC receiver, the PIO controller must be configured to dedicate the SSC receiver I/O lines to the
SSC peripheral mode.
Before using the SSC transmitter, the PIO controller must be configured to dedicate the SSC transmitter I/O lines
to the SSC peripheral mode.
32.5.2 Power Management
The SSC is not continuously clocked. The SSC interface may be clocked through the Power Management Control-
ler (PMC), therefore the programmer must first configure the PMC to enable the SSC clock.
32.5.3 Interrupt
The SSC interface has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling interrupts
requires programming the AIC before configuring the SSC.
All SSC interrupts can be enabled/disabled configuring the SSC Interrupt mask register. Each pending and
unmasked SSC interrupt will assert the SSC interrupt line. The SSC interrupt service routine can get the interrupt
origin by reading the SSC interrupt status register.
32.6 Functional Description
This chapter contains the functional description of the following: SSC Functional Block, Clock Management, Data
format, Start, Transmitter, Receiver and Frame Sync.
Interrupt
Management
Power
Management
Test
Management
SSC
Serial AUDIO
OS or RTOS Driver
Codec Frame
Management Line Interface
Time Slot
Management
Table 32-1. I/O Lines Description
Pin Name Pin Description Type
RF Receiver Frame Synchro Input/Output
RK Receiver Clock Input/Output
RD Receiver Data Input
TF Transmitter Frame Synchro Input/Output
TK Transmitter Clock Input/Output
TD Transmitter Data Output
411
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
The receiver and transmitter operate separately. However, they can work synchronously by programming the
receiver to use the transmit clock and/or to start a data transfer when transmission starts. Alternatively, this can be
done by programming the transmitter to use the receive clock and/or to start a data transfer when reception starts.
The transmitter and the receiver can be programmed to operate with the clock signals provided on either the TK or
RK pins. This allows the SSC to support many slave-mode data transfers. The maximum clock speed allowed on
the TK and RK pins is the master clock divided by 2.
Figure 32-3. SSC Functional Block Diagram
32.6.1 Clock Management
The transmitter clock can be generated by:
• an external clock received on the TK I/O pad
• the receiver clock
• the internal clock divider
The receiver clock can be generated by:
• an external clock received on the RK I/O pad
• the transmitter clock
• the internal clock divider
Interrupt Control
AIC
User
Interface
APB
MCK
Receive Clock
Controller
Start
Selector
TX Clock
RK Input
RF
TF
Clock Output
Controller
Frame Sync
Controller
Transmit Clock
Controller
Transmit Shift Register
Start
Selector
Transmit Sync
Holding Register
Transmit Holding
Register
Load Shift
RX clock
TX clock
TK Input
TF
TX PDC
RF
RD
RF
RK
Clock Output
Controller
Frame Sync
Controller
Receive Shift Register
Receive Sync
Holding Register
Receive Holding
Register
Load Shift
TD
TF
TK
RX Clock
RX PDC
Receiver
PDC
Transmitter
Clock
Divider
412
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Furthermore, the transmitter block can generate an external clock on the TK I/O pad, and the receiver block can
generate an external clock on the RK I/O pad.
This allows the SSC to support many Master and Slave Mode data transfers.
32.6.1.1 Clock Divider
Figure 32-4. Divided Clock Block Diagram
The Master Clock divider is determined by the 12-bit field DIV counter and comparator (so its maximal value is
4095) in the Clock Mode Register SSC_CMR, allowing a Master Clock division by up to 8190. The Divided Clock is
provided to both the Receiver and Transmitter. When this field is programmed to 0, the Clock Divider is not used
and remains inactive.
When DIV is set to a value equal to or greater than 1, the Divided Clock has a frequency of Master Clock divided by
2 times DIV. Each level of the Divided Clock has a duration of the Master Clock multiplied by DIV. This ensures a
50% duty cycle for the Divided Clock regardless of whether the DIV value is even or odd.
Figure 32-5. Divided Clock Generation
32.6.1.2 Transmitter Clock Management
The transmitter clock is generated from the receiver clock or the divider clock or an external clock scanned on the
TK I/O pad. The transmitter clock is selected by the CKS field in SSC_TCMR (Transmit Clock Mode Register).
Transmit Clock can be inverted independently by the CKI bits in SSC_TCMR.
Table 32-2.
Maximum Minimum
MCK / 2 MCK / 8190
MCK
Divided Clock
Clock Divider
/ 2 12-bit Counter
SSC_CMR
Master Clock
Divided Clock
DIV = 1
Master Clock
Divided Clock
DIV = 3
Divided Clock Frequency = MCK/2
Divided Clock Frequency = MCK/6
413
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
The transmitter can also drive the TK I/O pad continuously or be limited to the actual data transfer. The clock out-
put is configured by the SSC_TCMR register. The Transmit Clock Inversion (CKI) bits have no effect on the clock
outputs. Programming the TCMR register to select TK pin (CKS field) and at the same time Continuous Transmit
Clock (CKO field) might lead to unpredictable results.
Figure 32-6. Transmitter Clock Management
32.6.1.3 Receiver Clock Management
The receiver clock is generated from the transmitter clock or the divider clock or an external clock scanned on the
RK I/O pad. The Receive Clock is selected by the CKS field in SSC_RCMR (Receive Clock Mode Register).
Receive Clocks can be inverted independently by the CKI bits in SSC_RCMR.
The receiver can also drive the RK I/O pad continuously or be limited to the actual data transfer. The clock output
is configured by the SSC_RCMR register. The Receive Clock Inversion (CKI) bits have no effect on the clock out-
puts. Programming the RCMR register to select RK pin (CKS field) and at the same time Continuous Receive
Clock (CKO field) can lead to unpredictable results.
Figure 32-7. Receiver Clock Management
TK (pin)
Receiver
Clock
Divider
Clock
CKS
CKO Data Transfer
CKI CKG
Transmitter
Clock
Clock
Output
MUX Tri_state
Controller
Tri-state
Controller
INV
MUX
RK (pin)
Transmitter
Clock
Divider
Clock
CKS
CKO Data Transfer
CKI CKG
Receiver
Clock
Clock
Output
MUX Tri-state
Controller
Tri-state
Controller
INV
MUX
414
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.6.1.4 Serial Clock Ratio Considerations
The Transmitter and the Receiver can be programmed to operate with the clock signals provided on either the TK
or RK pins. This allows the SSC to support many slave-mode data transfers. In this case, the maximum clock
speed allowed on the RK pin is:
– Master Clock divided by 2 if Receiver Frame Synchro is input
– Master Clock divided by 3 if Receiver Frame Synchro is output
In addition, the maximum clock speed allowed on the TK pin is:
– Master Clock divided by 6 if Transmit Frame Synchro is input
– Master Clock divided by 2 if Transmit Frame Synchro is output
32.6.2 Transmitter Operations
A transmitted frame is triggered by a start event and can be followed by synchronization data before data
transmission.
The start event is configured by setting the Transmit Clock Mode Register (SSC_TCMR). See “Start” on page 415.
The frame synchronization is configured setting the Transmit Frame Mode Register (SSC_TFMR). See “Frame
Sync” on page 417.
To transmit data, the transmitter uses a shift register clocked by the transmitter clock signal and the start mode
selected in the SSC_TCMR. Data is written by the application to the SSC_THR register then transferred to the shift
register according to the data format selected.
When both the SSC_THR and the transmit shift register are empty, the status flag TXEMPTY is set in SSC_SR.
When the Transmit Holding register is transferred in the Transmit shift register, the status flag TXRDY is set in
SSC_SR and additional data can be loaded in the holding register.
Figure 32-8. Transmitter Block Diagram
32.6.3 Receiver Operations
A received frame is triggered by a start event and can be followed by synchronization data before data
transmission.
The start event is configured setting the Receive Clock Mode Register (SSC_RCMR). See “Start” on page 415.
Transmit Shift Register
Start
Selector
SSC_TSHRSSC_THR
Transmitter Clock
TD
SSC_TFMR.FSLENSSC_TFMR.DATLEN
SSC_CR.TXEN
SSC_CR.TXDIS
SSC_TCMR.STTDLY
SSC_TFMR.FSDEN
SSC_TFMR.DATNB
SSC_SR.TXEN
SSC_TFMR.DATDEF
SSC_TFMR.MSBF
SSC_TCMR.STTDLY
SSC_TFMR.FSDEN
0
1
10
RF TF
415
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
The frame synchronization is configured setting the Receive Frame Mode Register (SSC_RFMR). See “Frame
Sync” on page 417.
The receiver uses a shift register clocked by the receiver clock signal and the start mode selected in the
SSC_RCMR. The data is transferred from the shift register depending on the data format selected.
When the receiver shift register is full, the SSC transfers this data in the holding register, the status flag RXRDY is
set in SSC_SR and the data can be read in the receiver holding register. If another transfer occurs before read of
the RHR register, the status flag OVERUN is set in SSC_SR and the receiver shift register is transferred in the
RHR register.
Figure 32-9. Receiver Block Diagram
32.6.4 Start
The transmitter and receiver can both be programmed to start their operations when an event occurs, respectively
in the Transmit Start Selection (START) field of SSC_TCMR and in the Receive Start Selection (START) field of
SSC_RCMR.
Under the following conditions the start event is independently programmable:
• Continuous. In this case, the transmission starts as soon as a word is written in SSC_THR and the reception
starts as soon as the Receiver is enabled.
• Synchronously with the transmitter/receiver
• On detection of a falling/rising edge on TF/RF
• On detection of a low level/high level on TF/RF
• On detection of a level change or an edge on TF/RF
A start can be programmed in the same manner on either side of the Transmit/Receive Clock Register
(RCMR/TCMR). Thus, the start could be on TF (Transmit) or RF (Receive).
Moreover, the Receiver can start when data is detected in the bit stream with the Compare Functions.
Detection on TF/RF input/output is done by the field FSOS of the Transmit/Receive Frame Mode Register
(TFMR/RFMR).
Receive Shift Register
Start
Selector
SSC_RHRSSC_RSHR
Receiver Clock
RD
SSC_RFMR.FSLEN SSC_RFMR.DATLEN
RF
SSC_CR.RXEN
SSC_CR.RXDIS
SSC_SR.RXEN
SSC_RFMR.MSBF
SSC_RCMR.STTDLY
SSC_RFMR.DATNB
TF
416
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 32-10. Transmit Start Mode
Figure 32-11. Receive Pulse/Edge Start Modes
X
TK
TF
(Input)
TD
(Output)
TD
(Output)
TD
(Output)
TD
(Output)
TD
(Output)
TD
(Output)
XBOB1
XBO B1
BO B1
BO B1
BO B1BO B1
BO B1B1
BO
X
X
X
STTDLY
STTDLY
STTDLY
STTDLY
STTDLY
STTDLY
Start = Falling Edge on TF
Start = Rising Edge on TF
Start = Low Level on TF
Start = High Level on TF
Start = Any Edge on TF
Start = Level Change on TF
X
RK
RF
(Input)
RD
(Input)
RD
(Input)
RD
(Input)
RD
(Input)
RD
(Input)
RD
(Input)
XBOB1
XBO B1
BO B1
BO B1
BO B1BO B1
BO B1B1
BO
X
X
X
STTDLY
STTDLY
STTDLY
STTDLY
STTDLY
STTDLY
Start = Falling Edge on RF
Start = Rising Edge on RF
Start = Low Level on RF
Start = High Level on RF
Start = Any Edge on RF
Start = Level Change on RF
417
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.6.5 Frame Sync
The Transmitter and Receiver Frame Sync pins, TF and RF, can be programmed to generate different kinds of
frame synchronization signals. The Frame Sync Output Selection (FSOS) field in the Receive Frame Mode Regis-
ter (SSC_RFMR) and in the Transmit Frame Mode Register (SSC_TFMR) are used to select the required
waveform.
• Programmable low or high levels during data transfer are supported.
• Programmable high levels before the start of data transfers or toggling are also supported.
If a pulse waveform is selected, the Frame Sync Length (FSLEN) field in SSC_RFMR and SSC_TFMR programs
the length of the pulse, from 1 bit time up to 16 bit time.
The periodicity of the Receive and Transmit Frame Sync pulse output can be programmed through the Period
Divider Selection (PERIOD) field in SSC_RCMR and SSC_TCMR.
32.6.5.1 Frame Sync Data
Frame Sync Data transmits or receives a specific tag during the Frame Sync signal.
During the Frame Sync signal, the Receiver can sample the RD line and store the data in the Receive Sync Hold-
ing Register and the transmitter can transfer Transmit Sync Holding Register in the Shifter Register. The data
length to be sampled/shifted out during the Frame Sync signal is programmed by the FSLEN field in
SSC_RFMR/SSC_TFMR and has a maximum value of 16.
Concerning the Receive Frame Sync Data operation, if the Frame Sync Length is equal to or lower than the delay
between the start event and the actual data reception, the data sampling operation is performed in the Receive
Sync Holding Register through the Receive Shift Register.
The Transmit Frame Sync Operation is performed by the transmitter only if the bit Frame Sync Data Enable
(FSDEN) in SSC_TFMR is set. If the Frame Sync length is equal to or lower than the delay between the start event
and the actual data transmission, the normal transmission has priority and the data contained in the Transmit Sync
Holding Register is transferred in the Transmit Register, then shifted out.
32.6.5.2 Frame Sync Edge Detection
The Frame Sync Edge detection is programmed by the FSEDGE field in SSC_RFMR/SSC_TFMR. This sets the
corresponding flags RXSYN/TXSYN in the SSC Status Register (SSC_SR) on frame synchro edge detection (sig-
nals RF/TF).
32.6.6 Receive Compare Modes
Figure 32-12. Receive Compare Modes
32.6.6.1 Compare Functions
Length of the comparison patterns (Compare 0, Compare 1) and thus the number of bits they are compared to is
defined by FSLEN, but with a maximum value of 16 bits. Comparison is always done by comparing the last bits
received with the comparison pattern. Compare 0 can be one start event of the Receiver. In this case, the receiver
CMP0 CMP3
CMP2
CMP1 Ignored B0 B2
B1
Start
RK
RD
(Input)
FSLEN
Up to 16 Bits
(4 in This Example)
STDLY DATLEN
418
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
compares at each new sample the last bits received at the Compare 0 pattern contained in the Compare 0 Register
(SSC_RC0R). When this start event is selected, the user can program the Receiver to start a new data transfer
either by writing a new Compare 0, or by receiving continuously until Compare 1 occurs. This selection is done with
the bit (STOP) in SSC_RCMR.
32.6.7 Data Format
The data framing format of both the transmitter and the receiver are programmable through the Transmitter Frame
Mode Register (SSC_TFMR) and the Receiver Frame Mode Register (SSC_RFMR). In either case, the user can
independently select:
• the event that starts the data transfer (START)
• the delay in number of bit periods between the start event and the first data bit (STTDLY)
• the length of the data (DATLEN)
• the number of data to be transferred for each start event (DATNB).
• the length of synchronization transferred for each start event (FSLEN)
• the bit sense: most or lowest significant bit first (MSBF)
Additionally, the transmitter can be used to transfer synchronization and select the level driven on the TD pin while
not in data transfer operation. This is done respectively by the Frame Sync Data Enable (FSDEN) and by the Data
Default Value (DATDEF) bits in SSC_TFMR.
419
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 32-13. Transmit and Receive Frame Format in Edge/Pulse Start Modes
Note: 1. Example of input on falling edge of TF/RF.
Figure 32-14. Transmit Frame Format in Continuous Mode
Note: 1. STTDLY is set to 0. In this example, SSC_THR is loaded twice. FSDEN value has no effect on the transmission.
SyncData cannot be output in continuous mode.
Table 32-3. Data Frame Registers
Transmitter Receiver Field Length Comment
SSC_TFMR SSC_RFMR DATLEN Up to 32 Size of word
SSC_TFMR SSC_RFMR DATNB Up to 16 Number of words transmitted in frame
SSC_TFMR SSC_RFMR MSBF Most significant bit first
SSC_TFMR SSC_RFMR FSLEN Up to 16 Size of Synchro data register
SSC_TFMR DATDEF 0 or 1 Data default value ended
SSC_TFMR FSDEN Enable send SSC_TSHR
SSC_TCMR SSC_RCMR PERIOD Up to 512 Frame size
SSC_TCMR SSC_RCMR STTDLY Up to 255 Size of transmit start delay
Sync Data
Default
STTDLY
Sync Data Ignored
RD
Default
Data
DATLEN
Data
Data
Data
DATLEN
Data
Data Default
Default
Ignored
Sync Data
Sync Data
FSLEN
TF/RF
(1)
Start
Start
From SSC_TSHR From SSC_THR
From SSC_THR
From SSC_THR
From SSC_THR
To SSC_RHR To SSC_RHRTo SSC_RSHR
TD
(If FSDEN = 0)
TD
(If FSDEN = 1)
DATNB
PERIOD
FromDATDEF FromDATDEF
From DATDEF From DATDEF
DATLEN
Data
DATLEN
Data Default
Start
From SSC_THR From SSC_THR
TD
Start: 1. TXEMPTY set to 1
2. Write into the SSC_THR
420
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 32-15. Receive Frame Format in Continuous Mode
Note: 1. STTDLY is set to 0.
32.6.8 Loop Mode
The receiver can be programmed to receive transmissions from the transmitter. This is done by setting the Loop
Mode (LOOP) bit in SSC_RFMR. In this case, RD is connected to TD, RF is connected to TF and RK is connected
to TK.
32.6.9 Interrupt
Most bits in SSC_SR have a corresponding bit in interrupt management registers.
The SSC can be programmed to generate an interrupt when it detects an event. The interrupt is controlled by writ-
ing SSC_IER (Interrupt Enable Register) and SSC_IDR (Interrupt Disable Register) These registers enable and
disable, respectively, the corresponding interrupt by setting and clearing the corresponding bit in SSC_IMR (Inter-
rupt Mask Register), which controls the generation of interrupts by asserting the SSC interrupt line connected to
the AIC.
Figure 32-16. Interrupt Block Diagram
32.7 SSC Application Examples
The SSC can support several serial communication modes used in audio or high speed serial links. Some standard
applications are shown in the following figures. All serial link applications supported by the SSC are not listed here.
Data
DATLEN
Data
DATLEN
Start = Enable Receiver
To SSC_RHR To SSC_RHR
RD
SSC_IMR
PDC
Interrupt
Control
SSC Interrupt
Set
RXRDY
OVRUN
RXSYNC
Receiver
Transmitter
TXRDY
TXEMPTY
TXSYNC
TXBUFE
ENDTX
RXBUFF
ENDRX
Clear
SSC_IER SSC_IDR
421
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 32-17. Audio Application Block Diagram
Figure 32-18. Codec Application Block Diagram
SSC
RK
RF
RD
TD
TF
TK
Clock SCK
Word Select WS
Data SD
I2S
RECEIVER
Clock SCK
Word Select WS
Data SD
Right Channel
Left Channel
MSB MSB
LSB
SSC
RK
RF
RD
TD
TF
TK
Serial Data Clock (SCLK)
Frame sync (FSYNC)
Serial Data Out
Serial Data In
CODEC
Serial Data Clock (SCLK)
Frame sync (FSYNC)
Serial Data Out
Serial Data In
First Time Slot
Dstart Dend
422
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Figure 32-19. Time Slot Application Block Diagram
SSC
RK
RF
RD
TD
TF
TK
SCLK
FSYNC
Data Out
Data in
CODEC
First
Time Slot
Serial Data Clock (SCLK)
Frame sync (FSYNC)
Serial Data Out
Serial Data in
CODEC
Second
Time Slot
First Time Slot Second Time Slot
Dstart Dend
423
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8 Syncrhronous Serial Controller (SSC) User Interface
Table 32-4. Register Mapping
Offset Register Name Access Reset
0x0 Control Register SSC_CR Write –
0x4 Clock Mode Register SSC_CMR Read-write 0x0
0x8 Reserved – – –
0xC Reserved – – –
0x10 Receive Clock Mode Register SSC_RCMR Read-write 0x0
0x14 Receive Frame Mode Register SSC_RFMR Read-write 0x0
0x18 Transmit Clock Mode Register SSC_TCMR Read-write 0x0
0x1C Transmit Frame Mode Register SSC_TFMR Read-write 0x0
0x20 Receive Holding Register SSC_RHR Read 0x0
0x24 Transmit Holding Register SSC_THR Write –
0x28 Reserved – – –
0x2C Reserved – – –
0x30 Receive Sync. Holding Register SSC_RSHR Read 0x0
0x34 Transmit Sync. Holding Register SSC_TSHR Read-write 0x0
0x38 Receive Compare 0 Register SSC_RC0R Read-write 0x0
0x3C Receive Compare 1 Register SSC_RC1R Read-write 0x0
0x40 Status Register SSC_SR Read 0x000000CC
0x44 Interrupt Enable Register SSC_IER Write –
0x48 Interrupt Disable Register SSC_IDR Write –
0x4C Interrupt Mask Register SSC_IMR Read 0x0
0x50-0xFC Reserved – – –
0x100- 0x124 Reserved for Peripheral Data Controller (PDC) – – –
424
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.1 SSC Control Register
Name: SSC_CR
Access Type: Write-only
• RXEN: Receive Enable
0 = No effect.
1 = Enables Receive if RXDIS is not set.
• RXDIS: Receive Disable
0 = No effect.
1 = Disables Receive. If a character is currently being received, disables at end of current character reception.
• TXEN: Transmit Enable
0 = No effect.
1 = Enables Transmit if TXDIS is not set.
• TXDIS: Transmit Disable
0 = No effect.
1 = Disables Transmit. If a character is currently being transmitted, disables at end of current character transmission.
• SWRST: Software Reset
0 = No effect.
1 = Performs a software reset. Has priority on any other bit in SSC_CR.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
SWRST–––––TXDISTXEN
76543210
––––––RXDISRXEN
425
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.2 SSC Clock Mode Register
Name: SSC_CMR
Access Type: Read-write
• DIV: Clock Divider
0 = The Clock Divider is not active.
Any Other Value: The Divided Clock equals the Master Clock divided by 2 times DIV. The maximum bit rate is MCK/2. The
minimum bit rate is MCK/2 x 4095 = MCK/8190.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––– DIV
76543210
DIV
426
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.3 SSC Receive Clock Mode Register
Name: SSC_RCMR
Access Type: Read-write
• CKS: Receive Clock Selection
• CKO: Receive Clock Output Mode Selection
• CKI: Receive Clock Inversion
0 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock falling edge. The Frame Sync signal
output is shifted out on Receive Clock rising edge.
1 = The data inputs (Data and Frame Sync signals) are sampled on Receive Clock rising edge. The Frame Sync signal out-
put is shifted out on Receive Clock falling edge.
CKI affects only the Receive Clock and not the output clock signal.
31 30 29 28 27 26 25 24
PERIOD
23 22 21 20 19 18 17 16
STTDLY
15 14 13 12 11 10 9 8
– – – STOP START
76543210
CKG CKI CKO CKS
CKS Selected Receive Clock
0x0 Divided Clock
0x1 TK Clock signal
0x2 RK pin
0x3 Reserved
CKO Receive Clock Output Mode RK pin
0x0 None Input-only
0x1 Continuous Receive Clock Output
0x2 Receive Clock only during data transfers Output
0x3-0x7 Reserved
427
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• CKG: Receive Clock Gating Selection
• START: Receive Start Selection
• STOP: Receive Stop Selection
0 = After completion of a data transfer when starting with a Compare 0, the receiver stops the data transfer and waits for a
new compare 0.
1 = After starting a receive with a Compare 0, the receiver operates in a continuous mode until a Compare 1 is detected.
• STTDLY: Receive Start Delay
If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of reception.
When the Receiver is programmed to start synchronously with the Transmitter, the delay is also applied.
Note: It is very important that STTDLY be set carefully. If STTDLY must be set, it should be done in relation to TAG
(Receive Sync Data) reception.
• PERIOD: Receive Period Divider Selection
This field selects the divider to apply to the selected Receive Clock in order to generate a new Frame Sync Signal. If 0, no
PERIOD signal is generated. If not 0, a PERIOD signal is generated each 2 x (PERIOD+1) Receive Clock.
CKG Receive Clock Gating
0x0 None, continuous clock
0x1 Receive Clock enabled only if RF Low
0x2 Receive Clock enabled only if RF High
0x3 Reserved
START Receive Start
0x0 Continuous, as soon as the receiver is enabled, and immediately after the end of transfer of the previous data.
0x1 Transmit start
0x2 Detection of a low level on RF signal
0x3 Detection of a high level on RF signal
0x4 Detection of a falling edge on RF signal
0x5 Detection of a rising edge on RF signal
0x6 Detection of any level change on RF signal
0x7 Detection of any edge on RF signal
0x8 Compare 0
0x9-0xF Reserved
428
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.4 SSC Receive Frame Mode Register
Name: SSC_RFMR
Access Type: Read-write
• DATLEN: Data Length
0 = Forbidden value (1-bit data length not supported).
Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the
PDC2 assigned to the Receiver. If DATLEN is lower or equal to 7, data transfers are in bytes. If DATLEN is between 8 and
15 (included), half-words are transferred, and for any other value, 32-bit words are transferred.
• LOOP: Loop Mode
0 = Normal operating mode.
1 = RD is driven by TD, RF is driven by TF and TK drives RK.
• MSBF: Most Significant Bit First
0 = The lowest significant bit of the data register is sampled first in the bit stream.
1 = The most significant bit of the data register is sampled first in the bit stream.
• DATNB: Data Number per Frame
This field defines the number of data words to be received after each transfer start, which is equal to (DATNB + 1).
• FSLEN: Receive Frame Sync Length
This field defines the number of bits sampled and stored in the Receive Sync Data Register. When this mode is selected by
the START field in the Receive Clock Mode Register, it also determines the length of the sampled data to be compared to
the Compare 0 or Compare 1 register.
This field is used with FSLEN_EXT to determine the pulse length of the Receive Frame Sync signal.
Pulse length is equal to FSLEN + 1 Receive Clock periods.
31 30 29 28 27 26 25 24
––– ––––FSEDGE
23 22 21 20 19 18 17 16
– FSOS FSLEN
15 14 13 12 11 10 9 8
––– – DATNB
765 4 3210
MSBF – LOOP DATLEN
429
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• FSOS: Receive Frame Sync Output Selection
• FSEDGE: Frame Sync Edge Detection
Determines which edge on Frame Sync will generate the interrupt RXSYN in the SSC Status Register.
FSOS Selected Receive Frame Sync Signal RF Pin
0x0 None Input-only
0x1 Negative Pulse Output
0x2 Positive Pulse Output
0x3 Driven Low during data transfer Output
0x4 Driven High during data transfer Output
0x5 Toggling at each start of data transfer Output
0x6-0x7 Reserved Undefined
FSEDGE Frame Sync Edge Detection
0x0 Positive Edge Detection
0x1 Negative Edge Detection
430
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.5 SSC Transmit Clock Mode Register
Name: SSC_TCMR
Access Type: Read-write
• CKS: Transmit Clock Selection
• CKO: Transmit Clock Output Mode Selection
• CKI: Transmit Clock Inversion
0 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock falling edge. The Frame sync signal
input is sampled on Transmit clock rising edge.
1 = The data outputs (Data and Frame Sync signals) are shifted out on Transmit Clock rising edge. The Frame sync signal
input is sampled on Transmit clock falling edge.
CKI affects only the Transmit Clock and not the output clock signal.
• CKG: Transmit Clock Gating Selection
31 30 29 28 27 26 25 24
PERIOD
23 22 21 20 19 18 17 16
STTDLY
15 14 13 12 11 10 9 8
–––– START
76543210
CKG CKI CKO CKS
CKS Selected Transmit Clock
0x0 Divided Clock
0x1 RK Clock signal
0x2 TK Pin
0x3 Reserved
CKO Transmit Clock Output Mode TK pin
0x0 None Input-only
0x1 Continuous Transmit Clock Output
0x2 Transmit Clock only during data transfers Output
0x3-0x7 Reserved
CKG Transmit Clock Gating
0x0 None, continuous clock
431
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• START: Transmit Start Selection
• STTDLY: Transmit Start Delay
If STTDLY is not 0, a delay of STTDLY clock cycles is inserted between the start event and the actual start of transmission
of data. When the Transmitter is programmed to start synchronously with the Receiver, the delay is also applied.
Note: STTDLY must be set carefully. If STTDLY is too short in respect to TAG (Transmit Sync Data) emission, data is emit-
ted instead of the end of TAG.
• PERIOD: Transmit Period Divider Selection
This field selects the divider to apply to the selected Transmit Clock to generate a new Frame Sync Signal. If 0, no period
signal is generated. If not 0, a period signal is generated at each 2 x (PERIOD+1) Transmit Clock.
0x1 Transmit Clock enabled only if TF Low
0x2 Transmit Clock enabled only if TF High
0x3 Reserved
CKG Transmit Clock Gating
START Transmit Start
0x0 Continuous, as soon as a word is written in the SSC_THR Register (if Transmit is enabled), and
immediately after the end of transfer of the previous data.
0x1 Receive start
0x2 Detection of a low level on TF signal
0x3 Detection of a high level on TF signal
0x4 Detection of a falling edge on TF signal
0x5 Detection of a rising edge on TF signal
0x6 Detection of any level change on TF signal
0x7 Detection of any edge on TF signal
0x8 - 0xF Reserved
432
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.6 SSC Transmit Frame Mode Register
Name: SSC_TFMR
Access Type: Read-write
• DATLEN: Data Length
0 = Forbidden value (1-bit data length not supported).
Any other value: The bit stream contains DATLEN + 1 data bits. Moreover, it defines the transfer size performed by the
PDC2 assigned to the Transmit. If DATLEN is lower or equal to 7, data transfers are bytes, if DATLEN is between 8 and 15
(included), half-words are transferred, and for any other value, 32-bit words are transferred.
• DATDEF: Data Default Value
This bit defines the level driven on the TD pin while out of transmission. Note that if the pin is defined as multi-drive by the
PIO Controller, the pin is enabled only if the SCC TD output is 1.
• MSBF: Most Significant Bit First
0 = The lowest significant bit of the data register is shifted out first in the bit stream.
1 = The most significant bit of the data register is shifted out first in the bit stream.
• DATNB: Data Number per frame
This field defines the number of data words to be transferred after each transfer start, which is equal to (DATNB +1).
• FSLEN: Transmit Frame Sync Length
This field defines the length of the Transmit Frame Sync signal and the number of bits shifted out from the Transmit Sync
Data Register if FSDEN is 1.
This field is used with FSLEN_EXT to determine the pulse length of the Transmit Frame Sync signal.
Pulse length is equal to FSLEN + 1 Transmit Clock periods.
31 30 29 28 27 26 25 24
––– ––––FSEDGE
23 22 21 20 19 18 17 16
FSDEN FSOS FSLEN
15 14 13 12 11 10 9 8
––– – DATNB
765 4 3210
M S B F – DAT D E F DAT L E N
433
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• FSOS: Transmit Frame Sync Output Selection
• FSDEN: Frame Sync Data Enable
0 = The TD line is driven with the default value during the Transmit Frame Sync signal.
1 = SSC_TSHR value is shifted out during the transmission of the Transmit Frame Sync signal.
• FSEDGE: Frame Sync Edge Detection
Determines which edge on frame sync will generate the interrupt TXSYN (Status Register).
FSOS Selected Transmit Frame Sync Signal TF Pin
0x0 None Input-only
0x1 Negative Pulse Output
0x2 Positive Pulse Output
0x3 Driven Low during data transfer Output
0x4 Driven High during data transfer Output
0x5 Toggling at each start of data transfer Output
0x6-0x7 Reserved Undefined
FSEDGE Frame Sync Edge Detection
0x0 Positive Edge Detection
0x1 Negative Edge Detection
434
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.7 SSC Receive Holding Register
Name: SSC_RHR
Access Type: Read-only
• RDAT: Receive Data
Right aligned regardless of the number of data bits defined by DATLEN in SSC_RFMR.
32.8.8 SSC Transmit Holding Register
Name: SSC_THR
Access Type: Write-only
• TDAT: Transmit Data
Right aligned regardless of the number of data bits defined by DATLEN in SSC_TFMR.
31 30 29 28 27 26 25 24
RDAT
23 22 21 20 19 18 17 16
RDAT
15 14 13 12 11 10 9 8
RDAT
76543210
RDAT
31 30 29 28 27 26 25 24
TDAT
23 22 21 20 19 18 17 16
TDAT
15 14 13 12 11 10 9 8
TDAT
76543210
TDAT
435
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.9 SSC Receive Synchronization Holding Register
Name: SSC_RSHR
Access Type: Read-only
• RSDAT: Receive Synchronization Data
32.8.10 SSC Transmit Synchronization Holding Register
Name: SSC_TSHR
Access Type: Read-write
• TSDAT: Transmit Synchronization Data
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
RSDAT
76543210
RSDAT
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
TSDAT
76543210
TSDAT
436
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.11 SSC Receive Compare 0 Register
Name: SSC_RC0R
Access Type: Read-write
• CP0: Receive Compare Data 0
32.8.12 SSC Receive Compare 1 Register
Name: SSC_RC1R
Access Type: Read-write
• CP1: Receive Compare Data 1
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
CP0
76543210
CP0
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
CP1
76543210
CP1
437
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.13 SSC Status Register
Name: SSC_SR
Access Type: Read-only
• TXRDY: Transmit Ready
0 = Data has been loaded in SSC_THR and is waiting to be loaded in the Transmit Shift Register (TSR).
1 = SSC_THR is empty.
• TXEMPTY: Transmit Empty
0 = Data remains in SSC_THR or is currently transmitted from TSR.
1 = Last data written in SSC_THR has been loaded in TSR and last data loaded in TSR has been transmitted.
• ENDTX: End of Transmission
0 = The register SSC_TCR has not reached 0 since the last write in SSC_TCR or SSC_TNCR.
1 = The register SSC_TCR has reached 0 since the last write in SSC_TCR or SSC_TNCR.
• TXBUFE: Transmit Buffer Empty
0 = SSC_TCR or SSC_TNCR have a value other than 0.
1 = Both SSC_TCR and SSC_TNCR have a value of 0.
• RXRDY: Receive Ready
0 = SSC_RHR is empty.
1 = Data has been received and loaded in SSC_RHR.
• OVRUN: Receive Overrun
0 = No data has been loaded in SSC_RHR while previous data has not been read since the last read of the Status
Register.
1 = Data has been loaded in SSC_RHR while previous data has not yet been read since the last read of the Status
Register.
• ENDRX: End of Reception
0 = Data is written on the Receive Counter Register or Receive Next Counter Register.
1 = End of PDC transfer when Receive Counter Register has arrived at zero.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––RXENTXEN
15 14 13 12 11 10 9 8
––––RXSYNTXSYN CP1 CP0
76543210
RXBUFF ENDRX OVRUN RXRDY TXBUFE ENDTX TXEMPTY TXRDY
438
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• RXBUFF: Receive Buffer Full
0 = SSC_RCR or SSC_RNCR have a value other than 0.
1 = Both SSC_RCR and SSC_RNCR have a value of 0.
•CP0: Compare 0
0 = A compare 0 has not occurred since the last read of the Status Register.
1 = A compare 0 has occurred since the last read of the Status Register.
•CP1: Compare 1
0 = A compare 1 has not occurred since the last read of the Status Register.
1 = A compare 1 has occurred since the last read of the Status Register.
• TXSYN: Transmit Sync
0 = A Tx Sync has not occurred since the last read of the Status Register.
1 = A Tx Sync has occurred since the last read of the Status Register.
• RXSYN: Receive Sync
0 = An Rx Sync has not occurred since the last read of the Status Register.
1 = An Rx Sync has occurred since the last read of the Status Register.
• TXEN: Transmit Enable
0 = Transmit is disabled.
1 = Transmit is enabled.
• RXEN: Receive Enable
0 = Receive is disabled.
1 = Receive is enabled.
439
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.14 SSC Interrupt Enable Register
Name: SSC_IER
Access Type: Write-only
• TXRDY: Transmit Ready Interrupt Enable
0 = No effect.
1 = Enables the Transmit Ready Interrupt.
• TXEMPTY: Transmit Empty Interrupt Enable
0 = No effect.
1 = Enables the Transmit Empty Interrupt.
• ENDTX: End of Transmission Interrupt Enable
0 = No effect.
1 = Enables the End of Transmission Interrupt.
• TXBUFE: Transmit Buffer Empty Interrupt Enable
0 = No effect.
1 = Enables the Transmit Buffer Empty Interrupt
• RXRDY: Receive Ready Interrupt Enable
0 = No effect.
1 = Enables the Receive Ready Interrupt.
• OVRUN: Receive Overrun Interrupt Enable
0 = No effect.
1 = Enables the Receive Overrun Interrupt.
• ENDRX: End of Reception Interrupt Enable
0 = No effect.
1 = Enables the End of Reception Interrupt.
• RXBUFF: Receive Buffer Full Interrupt Enable
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––RXSYNTXSYN CP1 CP0
76543210
RXBUFF ENDRX OVRUN RXRDY TXBUFE ENDTX TXEMPTY TXRDY
440
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
0 = No effect.
1 = Enables the Receive Buffer Full Interrupt.
• CP0: Compare 0 Interrupt Enable
0 = No effect.
1 = Enables the Compare 0 Interrupt.
• CP1: Compare 1 Interrupt Enable
0 = No effect.
1 = Enables the Compare 1 Interrupt.
• TXSYN: Tx Sync Interrupt Enable
0 = No effect.
1 = Enables the Tx Sync Interrupt.
• RXSYN: Rx Sync Interrupt Enable
0 = No effect.
1 = Enables the Rx Sync Interrupt.
441
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.15 SSC Interrupt Disable Register
Name: SSC_IDR
Access Type: Write-only
• TXRDY: Transmit Ready Interrupt Disable
0 = No effect.
1 = Disables the Transmit Ready Interrupt.
• TXEMPTY: Transmit Empty Interrupt Disable
0 = No effect.
1 = Disables the Transmit Empty Interrupt.
• ENDTX: End of Transmission Interrupt Disable
0 = No effect.
1 = Disables the End of Transmission Interrupt.
• TXBUFE: Transmit Buffer Empty Interrupt Disable
0 = No effect.
1 = Disables the Transmit Buffer Empty Interrupt.
• RXRDY: Receive Ready Interrupt Disable
0 = No effect.
1 = Disables the Receive Ready Interrupt.
• OVRUN: Receive Overrun Interrupt Disable
0 = No effect.
1 = Disables the Receive Overrun Interrupt.
• ENDRX: End of Reception Interrupt Disable
0 = No effect.
1 = Disables the End of Reception Interrupt.
• RXBUFF: Receive Buffer Full Interrupt Disable
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––RXSYNTXSYN CP1 CP0
76543210
RXBUFF ENDRX OVRUN RXRDY TXBUFE ENDTX TXEMPTY TXRDY
442
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
0 = No effect.
1 = Disables the Receive Buffer Full Interrupt.
• CP0: Compare 0 Interrupt Disable
0 = No effect.
1 = Disables the Compare 0 Interrupt.
• CP1: Compare 1 Interrupt Disable
0 = No effect.
1 = Disables the Compare 1 Interrupt.
• TXSYN: Tx Sync Interrupt Enable
0 = No effect.
1 = Disables the Tx Sync Interrupt.
• RXSYN: Rx Sync Interrupt Enable
0 = No effect.
1 = Disables the Rx Sync Interrupt.
443
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
32.8.16 SSC Interrupt Mask Register
Name: SSC_IMR
Access Type: Read-only
• TXRDY: Transmit Ready Interrupt Mask
0 = The Transmit Ready Interrupt is disabled.
1 = The Transmit Ready Interrupt is enabled.
• TXEMPTY: Transmit Empty Interrupt Mask
0 = The Transmit Empty Interrupt is disabled.
1 = The Transmit Empty Interrupt is enabled.
• ENDTX: End of Transmission Interrupt Mask
0 = The End of Transmission Interrupt is disabled.
1 = The End of Transmission Interrupt is enabled.
• TXBUFE: Transmit Buffer Empty Interrupt Mask
0 = The Transmit Buffer Empty Interrupt is disabled.
1 = The Transmit Buffer Empty Interrupt is enabled.
• RXRDY: Receive Ready Interrupt Mask
0 = The Receive Ready Interrupt is disabled.
1 = The Receive Ready Interrupt is enabled.
• OVRUN: Receive Overrun Interrupt Mask
0 = The Receive Overrun Interrupt is disabled.
1 = The Receive Overrun Interrupt is enabled.
• ENDRX: End of Reception Interrupt Mask
0 = The End of Reception Interrupt is disabled.
1 = The End of Reception Interrupt is enabled.
• RXBUFF: Receive Buffer Full Interrupt Mask
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––RXSYNTXSYN CP1 CP0
76543210
RXBUF ENDRX OVRUN RXRDY TXBUFE ENDTX TXEMPTY TXRDY
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0 = The Receive Buffer Full Interrupt is disabled.
1 = The Receive Buffer Full Interrupt is enabled.
• CP0: Compare 0 Interrupt Mask
0 = The Compare 0 Interrupt is disabled.
1 = The Compare 0 Interrupt is enabled.
• CP1: Compare 1 Interrupt Mask
0 = The Compare 1 Interrupt is disabled.
1 = The Compare 1 Interrupt is enabled.
• TXSYN: Tx Sync Interrupt Mask
0 = The Tx Sync Interrupt is disabled.
1 = The Tx Sync Interrupt is enabled.
• RXSYN: Rx Sync Interrupt Mask
0 = The Rx Sync Interrupt is disabled.
1 = The Rx Sync Interrupt is enabled.
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446
SAM7S Series [DATASHEET]
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447
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33. Timer Counter (TC)
33.1 Overview
The Timer Counter (TC) includes three identical 16-bit Timer Counter channels.
Each channel can be independently programmed to perform a wide range of functions including frequency mea-
surement, event counting, interval measurement, pulse generation, delay timing and pulse width modulation.
Each channel has three external clock inputs, five internal clock inputs and two multi-purpose input/output signals
which can be configured by the user. Each channel drives an internal interrupt signal which can be programmed to
generate processor interrupts.
The Timer Counter block has two global registers which act upon all three TC channels.
The Block Control Register allows the three channels to be started simultaneously with the same instruction.
The Block Mode Register defines the external clock inputs for each channel, allowing them to be chained.
Table 33-1 gives the assignment of the device Timer Counter clock inputs common to Timer Counter 0 to 2
Table 33-1. Timer Counter Clock Assignment
Name Definition
TIMER_CLOCK1 MCK/2
TIMER_CLOCK2 MCK/8
TIMER_CLOCK3 MCK/32
TIMER_CLOCK4 MCK/128
TIMER_CLOCK5 MCK/1024
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33.2 Block Diagram
Figure 33-1. Timer Counter Block Diagram
Timer/Counter
Channel 0
Timer/Counter
Channel 1
Timer/Counter
Channel 2
SYNC
Parallel I/O
Controller
TC1XC1S
TC0XC0S
TC2XC2S
INT0
INT1
INT2
TIOA0
TIOA1
TIOA2
TIOB0
TIOB1
TIOB2
XC0
XC1
XC2
XC0
XC1
XC2
XC0
XC1
XC2
TCLK0
TCLK1
TCLK2
TCLK0
TCLK1
TCLK2
TCLK0
TCLK1
TCLK2
TIOA1
TIOA2
TIOA0
TIOA2
TIOA0
TIOA1
Advanced
Interrupt
Controller
TCLK0
TCLK1
TCLK2
TIOA0
TIOB0
TIOA1
TIOB1
TIOA2
TIOB2
Timer Counter
TIOA
TIOB
TIOA
TIOB
TIOA
TIOB
SYNC
SYNC
TIMER_CLOCK2
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
TIMER_CLOCK1
Table 33-2. Signal Name Description
Block/Channel Signal Name Description
Channel Signal
XC0, XC1, XC2 External Clock Inputs
TIOA Capture Mode: Timer Counter Input
Waveform Mode: Timer Counter Output
TIOB Capture Mode: Timer Counter Input
Waveform Mode: Timer Counter Input/Output
INT Interrupt Signal Output
SYNC Synchronization Input Signal
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33.3 Pin Name List
33.4 Product Dependencies
33.4.1 I/O Lines
The pins used for interfacing the compliant external devices may be multiplexed with PIO lines. The programmer
must first program the PIO controllers to assign the TC pins to their peripheral functions.
33.4.2 Power Management
The TC is clocked through the Power Management Controller (PMC), thus the programmer must first configure the
PMC to enable the Timer Counter clock.
33.4.3 Interrupt
The TC has an interrupt line connected to the Advanced Interrupt Controller (AIC). Handling the TC interrupt
requires programming the AIC before configuring the TC.
Table 33-3. TC pin list
Pin Name Description Type
TCLK0-TCLK2 External Clock Input Input
TIOA0-TIOA2 I/O Line A I/O
TIOB0-TIOB2 I/O Line B I/O
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33.5 Functional Description
33.5.1 TC Description
The three channels of the Timer Counter are independent and identical in operation. The registers for channel pro-
gramming are listed in Table 33-4 on page 463.
33.5.2 16-bit Counter
Each channel is organized around a 16-bit counter. The value of the counter is incremented at each positive edge
of the selected clock. When the counter has reached the value 0xFFFF and passes to 0x0000, an overflow occurs
and the COVFS bit in TC_SR (Status Register) is set.
The current value of the counter is accessible in real time by reading the Counter Value Register, TC_CV. The
counter can be reset by a trigger. In this case, the counter value passes to 0x0000 on the next valid edge of the
selected clock.
33.5.3 Clock Selection
At block level, input clock signals of each channel can either be connected to the external inputs TCLK0, TCLK1 or
TCLK2, or be connected to the internal I/O signals TIOA0, TIOA1 or TIOA2 for chaining by programming the
TC_BMR (Block Mode). See Figure 33-2 on page 451.
Each channel can independently select an internal or external clock source for its counter:
• Internal clock signals: TIMER_CLOCK1, TIMER_CLOCK2, TIMER_CLOCK3, TIMER_CLOCK4,
TIMER_CLOCK5
• External clock signals: XC0, XC1 or XC2
This selection is made by the TCCLKS bits in the TC Channel Mode Register.
The selected clock can be inverted with the CLKI bit in TC_CMR. This allows counting on the opposite edges of the
clock.
The burst function allows the clock to be validated when an external signal is high. The BURST parameter in the
Mode Register defines this signal (none, XC0, XC1, XC2). See Figure 33-3 on page 451
Note: In all cases, if an external clock is used, the duration of each of its levels must be longer than the master clock period.
The external clock frequency must be at least 2.5 times lower than the master clock
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Figure 33-2. Clock Chaining Selection
Figure 33-3. Clock Selection
Timer/Counter
Channel 0
SYNC
TC0XC0S
TIOA0
TIOB0
XC0
XC1 = TCLK1
XC2 = TCLK2
TCLK0
TIOA1
TIOA2
Timer/Counter
Channel 1
SYNC
TC1XC1S
TIOA1
TIOB1
XC0 = TCLK2
XC1
XC2 = TCLK2
TCLK1
TIOA0
TIOA2
Timer/Counter
Channel 2
SYNC
TC2XC2S
TIOA2
TIOB2
XC0 = TCLK0
XC1 = TCLK1
XC2
TCLK2
TIOA0
TIOA1
TIMER_CLOCK1
TIMER_CLOCK2
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
XC0
XC1
XC2
TCCLKS
CLKI
BURST
1
Selected
Clock
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33.5.4 Clock Control
The clock of each counter can be controlled in two different ways: it can be enabled/disabled and started/stopped.
See Figure 33-4.
• The clock can be enabled or disabled by the user with the CLKEN and the CLKDIS commands in the Control
Register. In Capture Mode it can be disabled by an RB load event if LDBDIS is set to 1 in TC_CMR. In
Waveform Mode, it can be disabled by an RC Compare event if CPCDIS is set to 1 in TC_CMR. When
disabled, the start or the stop actions have no effect: only a CLKEN command in the Control Register can re-
enable the clock. When the clock is enabled, the CLKSTA bit is set in the Status Register.
• The clock can also be started or stopped: a trigger (software, synchro, external or compare) always starts the
clock. The clock can be stopped by an RB load event in Capture Mode (LDBSTOP = 1 in TC_CMR) or a RC
compare event in Waveform Mode (CPCSTOP = 1 in TC_CMR). The start and the stop commands have effect
only if the clock is enabled.
Figure 33-4. Clock Control
33.5.5 TC Operating Modes
Each channel can independently operate in two different modes:
• Capture Mode provides measurement on signals.
• Waveform Mode provides wave generation.
The TC Operating Mode is programmed with the WAVE bit in the TC Channel Mode Register.
In Capture Mode, TIOA and TIOB are configured as inputs.
In Waveform Mode, TIOA is always configured to be an output and TIOB is an output if it is not selected to be the
external trigger.
33.5.6 Trigger
A trigger resets the counter and starts the counter clock. Three types of triggers are common to both modes, and a
fourth external trigger is available to each mode.
The following triggers are common to both modes:
• Software Trigger: Each channel has a software trigger, available by setting SWTRG in TC_CCR.
QS
R
S
R
Q
CLKSTA CLKEN CLKDIS
Stop
Event
Disable
Event
Counter
Clock
Selected
Clock Trigger
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• SYNC: Each channel has a synchronization signal SYNC. When asserted, this signal has the same effect as a
software trigger. The SYNC signals of all channels are asserted simultaneously by writing TC_BCR (Block
Control) with SYNC set.
• Compare RC Trigger: RC is implemented in each channel and can provide a trigger when the counter value
matches the RC value if CPCTRG is set in TC_CMR.
The channel can also be configured to have an external trigger. In Capture Mode, the external trigger signal can be
selected between TIOA and TIOB. In Waveform Mode, an external event can be programmed on one of the follow-
ing signals: TIOB, XC0, XC1 or XC2. This external event can then be programmed to perform a trigger by setting
ENETRG in TC_CMR.
If an external trigger is used, the duration of the pulses must be longer than the master clock period in order to be
detected.
Regardless of the trigger used, it will be taken into account at the following active edge of the selected clock. This
means that the counter value can be read differently from zero just after a trigger, especially when a low frequency
signal is selected as the clock.
33.5.7 Capture Operating Mode
This mode is entered by clearing the WAVE parameter in TC_CMR (Channel Mode Register).
Capture Mode allows the TC channel to perform measurements such as pulse timing, frequency, period, duty cycle
and phase on TIOA and TIOB signals which are considered as inputs.
Figure 33-5 shows the configuration of the TC channel when programmed in Capture Mode.
33.5.8 Capture Registers A and B
Registers A and B (RA and RB) are used as capture registers. This means that they can be loaded with the counter
value when a programmable event occurs on the signal TIOA.
The LDRA parameter in TC_CMR defines the TIOA edge for the loading of register A, and the LDRB parameter
defines the TIOA edge for the loading of Register B.
RA is loaded only if it has not been loaded since the last trigger or if RB has been loaded since the last loading of
RA.
RB is loaded only if RA has been loaded since the last trigger or the last loading of RB.
Loading RA or RB before the read of the last value loaded sets the Overrun Error Flag (LOVRS) in TC_SR (Status
Register). In this case, the old value is overwritten.
33.5.9 Trigger Conditions
In addition to the SYNC signal, the software trigger and the RC compare trigger, an external trigger can be defined.
The ABETRG bit in TC_CMR selects TIOA or TIOB input signal as an external trigger. The ETRGEDG parameter
defines the edge (rising, falling or both) detected to generate an external trigger. If ETRGEDG = 0 (none), the
external trigger is disabled.
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SAM7S Series [DATASHEET]
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Figure 33-5. Capture Mode
TIMER_CLOCK1
TIMER_CLOCK2
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
XC0
XC1
XC2
TCCLKS
CLKI
QS
R
S
R
Q
CLKSTA CLKEN CLKDIS
BURST
TIOB
Register C
Capture
Register A
Capture
Register B Compare RC =
16-bit Counter
ABETRG
SWTRG
ETRGEDG CPCTRG
TC1_IMR
Trig
LDRBS
LDRAS
ETRGS
TC1_SR
LOVRS
COVFS
SYNC
1
MTIOB
TIOA
MTIOA
LDRA
LDBSTOP
If RA is not loaded
or RB is Loaded If RA is Loaded
LDBDIS
CPCS
INT
Edge
Detector
Edge
Detector
LDRB
Edge
Detector
CLK OVF
RESET
Timer/Counter Channel
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6175M–ATARM–26-Oct-12
33.5.10 Waveform Operating Mode
Waveform operating mode is entered by setting the WAVE parameter in TC_CMR (Channel Mode Register).
In Waveform Operating Mode the TC channel generates 1 or 2 PWM signals with the same frequency and inde-
pendently programmable duty cycles, or generates different types of one-shot or repetitive pulses.
In this mode, TIOA is configured as an output and TIOB is defined as an output if it is not used as an external event
(EEVT parameter in TC_CMR).
Figure 33-6 shows the configuration of the TC channel when programmed in Waveform Operating Mode.
33.5.11 Waveform Selection
Depending on the WAVSEL parameter in TC_CMR (Channel Mode Register), the behavior of TC_CV varies.
With any selection, RA, RB and RC can all be used as compare registers.
RA Compare is used to control the TIOA output, RB Compare is used to control the TIOB output (if correctly config-
ured) and RC Compare is used to control TIOA and/or TIOB outputs.
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Figure 33-6. Waveform Mode
TCCLKS
CLKI
QS
R
S
R
Q
CLKSTA CLKEN CLKDIS
CPCDIS
BURST
TIOB
Register A Register B Register C
Compare RA = Compare RB = Compare RC =
CPCSTOP
16-bit Counter
EEVT
EEVTEDG
SYNC
SWTRG
ENETRG
WAVSEL
TC1_IMR
Trig
ACPC
ACPA
AEEVT
ASWTRG
BCPC
BCPB
BEEVT
BSWTRG
TIOA
MTIOA
TIOB
MTIOB
CPAS
COVFS
ETRGS
TC1_SR
CPCS
CPBS
CLK
OVF
RESET
Output Controller
Output Controller
INT
1
Edge
Detector
Timer/Counter Channel
TIMER_CLOCK1
TIMER_CLOCK2
TIMER_CLOCK3
TIMER_CLOCK4
TIMER_CLOCK5
XC0
XC1
XC2
WAVSEL
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33.5.11.1 WAVSEL = 00
When WAVSEL = 00, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF has been reached, the
value of TC_CV is reset. Incrementation of TC_CV starts again and the cycle continues. See Figure 33-7.
An external event trigger or a software trigger can reset the value of TC_CV. It is important to note that the trigger
may occur at any time. See Figure 33-8.
RC Compare cannot be programmed to generate a trigger in this configuration. At the same time, RC Compare
can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable the counter clock (CPCDIS = 1 in
TC_CMR).
Figure 33-7. WAVSEL= 00 without trigger
Figure 33-8. WAVSEL= 00 with trigger
Time
Counter Value
RC
RB
RA
TIOB
TIOA
Counter cleared by compare match with 0xFFFF
0xFFFF
Waveform Examples
Time
Counter Value
RC
RB
RA
TIOB
TIOA
Counter cleared by compare match with 0xFFFF
0xFFFF
Waveform Examples
Counter cleared by trigger
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33.5.11.2 WAVSEL = 10
When WAVSEL = 10, the value of TC_CV is incremented from 0 to the value of RC, then automatically reset on a
RC Compare. Once the value of TC_CV has been reset, it is then incremented and so on. See Figure 33-9.
It is important to note that TC_CV can be reset at any time by an external event or a software trigger if both are pro-
grammed correctly. See Figure 33-10.
In addition, RC Compare can stop the counter clock (CPCSTOP = 1 in TC_CMR) and/or disable the counter clock
(CPCDIS = 1 in TC_CMR).
Figure 33-9. WAVSEL = 10 Without Trigger
Figure 33-10. WAVSEL = 10 With Trigger
Time
Counter Value
R
C
R
B
R
A
TIOB
TIOA
Counter cleared by compare match with RC
0xFFFF
Waveform Examples
Time
Counter Value
R
C
R
B
R
A
TIOB
TIOA
Counter cleared by compare match with RC
0xFFFF
Waveform Examples
Counter cleared by trigger
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33.5.11.3 WAVSEL = 01
When WAVSEL = 01, the value of TC_CV is incremented from 0 to 0xFFFF. Once 0xFFFF is reached, the value of
TC_CV is decremented to 0, then re-incremented to 0xFFFF and so on. See Figure 33-11.
A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while
TC_CV is incrementing, TC_CV then decrements. If a trigger is received while TC_CV is decrementing, TC_CV
then increments. See Figure 33-12.
RC Compare cannot be programmed to generate a trigger in this configuration.
At the same time, RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock
(CPCDIS = 1).
Figure 33-11. WAVSEL = 01 Without Trigger
Figure 33-12. WAVSEL = 01 With Trigger
Time
Counter Value
RC
RB
RA
TIOB
TIOA
Counter decremented by compare match with 0xFFFF
0xFFFF
Waveform Examples
Time
Counter Value
R
C
R
B
R
A
TIOB
TIOA
Counter cleared by compare match with RC
0xFFFF
Waveform Examples
Counter cleared by trigger
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33.5.11.4 WAVSEL = 11
When WAVSEL = 11, the value of TC_CV is incremented from 0 to RC. Once RC is reached, the value of TC_CV
is decremented to 0, then re-incremented to RC and so on. See Figure 33-13.
A trigger such as an external event or a software trigger can modify TC_CV at any time. If a trigger occurs while
TC_CV is incrementing, TC_CV then decrements. If a trigger is received while TC_CV is decrementing, TC_CV
then increments. See Figure 33-14.
RC Compare can stop the counter clock (CPCSTOP = 1) and/or disable the counter clock (CPCDIS = 1).
Figure 33-13. WAVSEL = 11 Without Trigger
Figure 33-14. WAVSEL = 11 With Trigger
Time
Counter Value
RC
RB
RA
TIOB
TIOA
Counter decremented by compare match with RC
0xFFFF
Waveform Examples
Time
Counter Value
TIOB
TIOA
Counter decremented by compare match with RC
0xFFFF
Waveform Examples
Counter decremented
by trigger
Counter incremented
by trigger
RC
RB
RA
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33.5.12 External Event/Trigger Conditions
An external event can be programmed to be detected on one of the clock sources (XC0, XC1, XC2) or TIOB. The
external event selected can then be used as a trigger.
The EEVT parameter in TC_CMR selects the external trigger. The EEVTEDG parameter defines the trigger edge
for each of the possible external triggers (rising, falling or both). If EEVTEDG is cleared (none), no external event is
defined.
If TIOB is defined as an external event signal (EEVT = 0), TIOB is no longer used as an output and the compare
register B is not used to generate waveforms and subsequently no IRQs. In this case the TC channel can only gen-
erate a waveform on TIOA.
When an external event is defined, it can be used as a trigger by setting bit ENETRG in TC_CMR.
As in Capture Mode, the SYNC signal and the software trigger are also available as triggers. RC Compare can also
be used as a trigger depending on the parameter WAVSEL.
33.5.13 Output Controller
The output controller defines the output level changes on TIOA and TIOB following an event. TIOB control is used
only if TIOB is defined as output (not as an external event).
The following events control TIOA and TIOB: software trigger, external event and RC compare. RA compare con-
trols TIOA and RB compare controls TIOB. Each of these events can be programmed to set, clear or toggle the
output as defined in the corresponding parameter in TC_CMR.
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33.6 Timer Counter (TC) User Interface
Notes: 1. Channel index ranges from 0 to 2.
2. Read-only if WAVE = 0
Table 33-4. Register Mapping
Offset(1) Register Name Access Reset
0x00 + channel * 0x40 + 0x00 Channel Control Register TC_CCR Write-only –
0x00 + channel * 0x40 + 0x04 Channel Mode Register TC_CMR Read-write 0
0x00 + channel * 0x40 + 0x08 Reserved
0x00 + channel * 0x40 + 0x0C Reserved
0x00 + channel * 0x40 + 0x10 Counter Value TC_CV Read-only 0
0x00 + channel * 0x40 + 0x14 Register A TC_RA Read-write(2) 0
0x00 + channel * 0x40 + 0x18 Register B TC_RB Read-write(2) 0
0x00 + channel * 0x40 + 0x1C Register C TC_RC Read-write 0
0x00 + channel * 0x40 + 0x20 Status Register TC_SR Read-only 0
0x00 + channel * 0x40 + 0x24 Interrupt Enable Register TC_IER Write-only –
0x00 + channel * 0x40 + 0x28 Interrupt Disable Register TC_IDR Write-only –
0x00 + channel * 0x40 + 0x2C Interrupt Mask Register TC_IMR Read-only 0
0xC0 Block Control Register TC_BCR Write-only –
0xC4 Block Mode Register TC_BMR Read-write 0
0xFC Reserved – – –
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33.6.1 TC Block Control Register
Register Name: TC_BCR
Access Type: Write-only
• SYNC: Synchro Command
0 = No effect.
1 = Asserts the SYNC signal which generates a software trigger simultaneously for each of the channels.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––––SYNC
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33.6.2 TC Block Mode Register
Register Name: TC_BMR
Access Type: Read-write
• TC0XC0S: External Clock Signal 0 Selection
• TC1XC1S: External Clock Signal 1 Selection
• TC2XC2S: External Clock Signal 2 Selection
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
– – TC2XC2S TC1XC1S TC0XC0S
TC0XC0S Signal Connected to XC0
00TCLK0
0 1 none
10TIOA1
11TIOA2
TC1XC1S Signal Connected to XC1
00TCLK1
0 1 none
10TIOA0
11TIOA2
TC2XC2S Signal Connected to XC2
00TCLK2
0 1 none
10TIOA0
11TIOA1
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33.6.3 TC Channel Control Register
Register Name: TC_CCRx [x=0..2]
Access Type: Write-only
• CLKEN: Counter Clock Enable Command
0 = No effect.
1 = Enables the clock if CLKDIS is not 1.
• CLKDIS: Counter Clock Disable Command
0 = No effect.
1 = Disables the clock.
• SWTRG: Software Trigger Command
0 = No effect.
1 = A software trigger is performed: the counter is reset and the clock is started.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
–––––SWTRGCLKDISCLKEN
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33.6.4 TC Channel Mode Register: Capture Mode
Register Name: TC_CMRx [x=0..2] (WAVE = 0)
Access Type: Read-write
• TCCLKS: Clock Selection
• CLKI: Clock Invert
0 = Counter is incremented on rising edge of the clock.
1 = Counter is incremented on falling edge of the clock.
• BURST: Burst Signal Selection
• LDBSTOP: Counter Clock Stopped with RB Loading
0 = Counter clock is not stopped when RB loading occurs.
1 = Counter clock is stopped when RB loading occurs.
• LDBDIS: Counter Clock Disable with RB Loading
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
– – – – LDRB LDRA
15 14 13 12 11 10 9 8
WAVE CPCTRG – – – ABETRG ETRGEDG
76543210
LDBDIS LDBSTOP BURST CLKI TCCLKS
TCCLKS Clock Selected
0 0 0 TIMER_CLOCK1
0 0 1 TIMER_CLOCK2
0 1 0 TIMER_CLOCK3
0 1 1 TIMER_CLOCK4
1 0 0 TIMER_CLOCK5
101XC0
110XC1
111XC2
BURST
0 0 The clock is not gated by an external signal.
0 1 XC0 is ANDed with the selected clock.
1 0 XC1 is ANDed with the selected clock.
1 1 XC2 is ANDed with the selected clock.
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0 = Counter clock is not disabled when RB loading occurs.
1 = Counter clock is disabled when RB loading occurs.
• ETRGEDG: External Trigger Edge Selection
• ABETRG: TIOA or TIOB External Trigger Selection
0 = TIOB is used as an external trigger.
1 = TIOA is used as an external trigger.
• CPCTRG: RC Compare Trigger Enable
0 = RC Compare has no effect on the counter and its clock.
1 = RC Compare resets the counter and starts the counter clock.
•WAVE
0 = Capture Mode is enabled.
1 = Capture Mode is disabled (Waveform Mode is enabled).
• LDRA: RA Loading Selection
• LDRB: RB Loading Selection
ETRGEDG Edge
0 0 none
0 1 rising edge
1 0 falling edge
1 1 each edge
LDRA Edge
0 0 none
0 1 rising edge of TIOA
1 0 falling edge of TIOA
1 1 each edge of TIOA
LDRB Edge
0 0 none
0 1 rising edge of TIOA
1 0 falling edge of TIOA
1 1 each edge of TIOA
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33.6.5 TC Channel Mode Register: Waveform Mode
Register Name: TC_CMRx [x=0..2] (WAVE = 1)
Access Type: Read-write
• TCCLKS: Clock Selection
• CLKI: Clock Invert
0 = Counter is incremented on rising edge of the clock.
1 = Counter is incremented on falling edge of the clock.
• BURST: Burst Signal Selection
• CPCSTOP: Counter Clock Stopped with RC Compare
0 = Counter clock is not stopped when counter reaches RC.
1 = Counter clock is stopped when counter reaches RC.
• CPCDIS: Counter Clock Disable with RC Compare
31 30 29 28 27 26 25 24
BSWTRG BEEVT BCPC BCPB
23 22 21 20 19 18 17 16
ASWTRG AEEVT ACPC ACPA
15 14 13 12 11 10 9 8
WAVE WAVSEL ENETRG EEVT EEVTEDG
76543210
CPCDIS CPCSTOP BURST CLKI TCCLKS
TCCLKS Clock Selected
0 0 0 TIMER_CLOCK1
0 0 1 TIMER_CLOCK2
0 1 0 TIMER_CLOCK3
0 1 1 TIMER_CLOCK4
1 0 0 TIMER_CLOCK5
101XC0
110XC1
111XC2
BURST
0 0 The clock is not gated by an external signal.
0 1 XC0 is ANDed with the selected clock.
1 0 XC1 is ANDed with the selected clock.
1 1 XC2 is ANDed with the selected clock.
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0 = Counter clock is not disabled when counter reaches RC.
1 = Counter clock is disabled when counter reaches RC.
• EEVTEDG: External Event Edge Selection
• EEVT: External Event Selection
Note: 1. If TIOB is chosen as the external event signal, it is configured as an input and no longer generates waveforms and subse-
quently no IRQs.
• ENETRG: External Event Trigger Enable
0 = The external event has no effect on the counter and its clock. In this case, the selected external event only controls the
TIOA output.
1 = The external event resets the counter and starts the counter clock.
• WAVSEL: Waveform Selection
•WAVE
0 = Waveform Mode is disabled (Capture Mode is enabled).
1 = Waveform Mode is enabled.
• ACPA: RA Compare Effect on TIOA
EEVTEDG Edge
0 0 none
0 1 rising edge
1 0 falling edge
1 1 each edge
EEVT Signal selected as external event TIOB Direction
0 0 TIOB input (1)
0 1 XC0 output
1 0 XC1 output
1 1 XC2 output
WAVSEL Effect
0 0 UP mode without automatic trigger on RC Compare
1 0 UP mode with automatic trigger on RC Compare
0 1 UPDOWN mode without automatic trigger on RC Compare
1 1 UPDOWN mode with automatic trigger on RC Compare
ACPA Effect
0 0 none
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SAM7S Series [DATASHEET]
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• ACPC: RC Compare Effect on TIOA
• AEEVT: External Event Effect on TIOA
• ASWTRG: Software Trigger Effect on TIOA
• BCPB: RB Compare Effect on TIOB
• BCPC: RC Compare Effect on TIOB
0 1 set
1 0 clear
1 1 toggle
ACPC Effect
0 0 none
0 1 set
1 0 clear
1 1 toggle
AEEVT Effect
0 0 none
0 1 set
1 0 clear
11toggle
ASWTRG Effect
0 0 none
0 1 set
1 0 clear
1 1 toggle
BCPB Effect
0 0 none
0 1 set
1 0 clear
11toggle
BCPC Effect
0 0 none
ACPA Effect
472
SAM7S Series [DATASHEET]
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• BEEVT: External Event Effect on TIOB
• BSWTRG: Software Trigger Effect on TIOB
0 1 set
1 0 clear
1 1 toggle
BEEVT Effect
0 0 none
0 1 set
1 0 clear
1 1 toggle
BSWTRG Effect
0 0 none
01set
1 0 clear
11toggle
BCPC Effect
473
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33.6.6 TC Counter Value Register
Register Name: TC_CVx [x=0..2]
Access Type: Read-only
• CV: Counter Value
CV contains the counter value in real time.
33.6.7 TC Register A
Register Name: TC_RAx [x=0..2]
Access Type: Read-only if WAVE = 0, Read-write if WAVE = 1
• RA: Register A
RA contains the Register A value in real time.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
CV
76543210
CV
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
RA
76543210
RA
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33.6.8 TC Register B
Register Name: TC_RBx [x=0..2]
Access Type: Read-only if WAVE = 0, Read-write if WAVE = 1
• RB: Register B
RB contains the Register B value in real time.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
RB
76543210
RB
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33.6.9 TC Register C
Register Name: TC_RCx [x=0..2]
Access Type: Read-write
• RC: Register C
RC contains the Register C value in real time.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
RC
76543210
RC
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33.6.10 TC Status Register
Register Name: TC_SRx [x=0..2]
Access Type: Read-only
• COVFS: Counter Overflow Status
0 = No counter overflow has occurred since the last read of the Status Register.
1 = A counter overflow has occurred since the last read of the Status Register.
• LOVRS: Load Overrun Status
0 = Load overrun has not occurred since the last read of the Status Register or WAVE = 1.
1 = RA or RB have been loaded at least twice without any read of the corresponding register since the last read of the Sta-
tus Register, if WAVE = 0.
• CPAS: RA Compare Status
0 = RA Compare has not occurred since the last read of the Status Register or WAVE = 0.
1 = RA Compare has occurred since the last read of the Status Register, if WAVE = 1.
• CPBS: RB Compare Status
0 = RB Compare has not occurred since the last read of the Status Register or WAVE = 0.
1 = RB Compare has occurred since the last read of the Status Register, if WAVE = 1.
• CPCS: RC Compare Status
0 = RC Compare has not occurred since the last read of the Status Register.
1 = RC Compare has occurred since the last read of the Status Register.
• LDRAS: RA Loading Status
0 = RA Load has not occurred since the last read of the Status Register or WAVE = 1.
1 = RA Load has occurred since the last read of the Status Register, if WAVE = 0.
• LDRBS: RB Loading Status
0 = RB Load has not occurred since the last read of the Status Register or WAVE = 1.
1 = RB Load has occurred since the last read of the Status Register, if WAVE = 0.
• ETRGS: External Trigger Status
0 = External trigger has not occurred since the last read of the Status Register.
1 = External trigger has occurred since the last read of the Status Register.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
–––––MTIOBMTIOACLKSTA
15 14 13 12 11 10 9 8
––––––––
76543210
ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS
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SAM7S Series [DATASHEET]
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• CLKSTA: Clock Enabling Status
0 = Clock is disabled.
1 = Clock is enabled.
• MTIOA: TIOA Mirror
0 = TIOA is low. If WAVE = 0, this means that TIOA pin is low. If WAVE = 1, this means that TIOA is driven low.
1 = TIOA is high. If WAVE = 0, this means that TIOA pin is high. If WAVE = 1, this means that TIOA is driven high.
• MTIOB: TIOB Mirror
0 = TIOB is low. If WAVE = 0, this means that TIOB pin is low. If WAVE = 1, this means that TIOB is driven low.
1 = TIOB is high. If WAVE = 0, this means that TIOB pin is high. If WAVE = 1, this means that TIOB is driven high.
478
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33.6.11 TC Interrupt Enable Register
Register Name: TC_IERx [x=0..2]
Access Type: Write-only
• COVFS: Counter Overflow
0 = No effect.
1 = Enables the Counter Overflow Interrupt.
• LOVRS: Load Overrun
0 = No effect.
1 = Enables the Load Overrun Interrupt.
• CPAS: RA Compare
0 = No effect.
1 = Enables the RA Compare Interrupt.
• CPBS: RB Compare
0 = No effect.
1 = Enables the RB Compare Interrupt.
• CPCS: RC Compare
0 = No effect.
1 = Enables the RC Compare Interrupt.
• LDRAS: RA Loading
0 = No effect.
1 = Enables the RA Load Interrupt.
• LDRBS: RB Loading
0 = No effect.
1 = Enables the RB Load Interrupt.
• ETRGS: External Trigger
0 = No effect.
1 = Enables the External Trigger Interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS
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33.6.12 TC Interrupt Disable Register
Register Name: TC_IDRx [x=0..2]
Access Type: Write-only
• COVFS: Counter Overflow
0 = No effect.
1 = Disables the Counter Overflow Interrupt.
• LOVRS: Load Overrun
0 = No effect.
1 = Disables the Load Overrun Interrupt (if WAVE = 0).
• CPAS: RA Compare
0 = No effect.
1 = Disables the RA Compare Interrupt (if WAVE = 1).
• CPBS: RB Compare
0 = No effect.
1 = Disables the RB Compare Interrupt (if WAVE = 1).
• CPCS: RC Compare
0 = No effect.
1 = Disables the RC Compare Interrupt.
• LDRAS: RA Loading
0 = No effect.
1 = Disables the RA Load Interrupt (if WAVE = 0).
• LDRBS: RB Loading
0 = No effect.
1 = Disables the RB Load Interrupt (if WAVE = 0).
• ETRGS: External Trigger
0 = No effect.
1 = Disables the External Trigger Interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS
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33.6.13 TC Interrupt Mask Register
Register Name: TC_IMRx [x=0..2]
Access Type: Read-only
• COVFS: Counter Overflow
0 = The Counter Overflow Interrupt is disabled.
1 = The Counter Overflow Interrupt is enabled.
• LOVRS: Load Overrun
0 = The Load Overrun Interrupt is disabled.
1 = The Load Overrun Interrupt is enabled.
• CPAS: RA Compare
0 = The RA Compare Interrupt is disabled.
1 = The RA Compare Interrupt is enabled.
• CPBS: RB Compare
0 = The RB Compare Interrupt is disabled.
1 = The RB Compare Interrupt is enabled.
• CPCS: RC Compare
0 = The RC Compare Interrupt is disabled.
1 = The RC Compare Interrupt is enabled.
• LDRAS: RA Loading
0 = The Load RA Interrupt is disabled.
1 = The Load RA Interrupt is enabled.
• LDRBS: RB Loading
0 = The Load RB Interrupt is disabled.
1 = The Load RB Interrupt is enabled.
• ETRGS: External Trigger
0 = The External Trigger Interrupt is disabled.
1 = The External Trigger Interrupt is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
ETRGS LDRBS LDRAS CPCS CPBS CPAS LOVRS COVFS
481
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34. Pulse Width Modulation Controller (PWM)
34.1 overview
The PWM macrocell controls several channels independently. Each channel controls one square output waveform.
Characteristics of the output waveform such as period, duty-cycle and polarity are configurable through the user
interface. Each channel selects and uses one of the clocks provided by the clock generator. The clock generator
provides several clocks resulting from the division of the PWM macrocell master clock.
All PWM macrocell accesses are made through APB mapped registers.
Channels can be synchronized, to generate non overlapped waveforms. All channels integrate a double buffering
system in order to prevent an unexpected output waveform while modifying the period or the duty-cycle.
34.2 Block Diagram
Figure 34-1. Pulse Width Modulation Controller Block Diagram
PWM
Controller
APB
PWMx
PWMx
PWMx
Channel
Update
Duty Cycle
Counter
PWM0
Channel
PIO
AIC
PMC MCK Clock Generator APB Interface Interrupt Generator
Clock
Selector
Period
Comparator
Update
Duty Cycle
Counter
Clock
Selector
Period
Comparator
PWM0
PWM0
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34.3 I/O Lines Description
Each channel outputs one waveform on one external I/O line.
34.4 Product Dependencies
34.4.1 I/O Lines
The pins used for interfacing the PWM may be multiplexed with PIO lines. The programmer must first program the
PIO controller to assign the desired PWM pins to their peripheral function. If I/O lines of the PWM are not used by
the application, they can be used for other purposes by the PIO controller.
All of the PWM outputs may or may not be enabled. If an application requires only four channels, then only four
PIO lines will be assigned to PWM outputs.
34.4.2 Power Management
The PWM is not continuously clocked. The programmer must first enable the PWM clock in the Power Manage-
ment Controller (PMC) before using the PWM. However, if the application does not require PWM operations, the
PWM clock can be stopped when not needed and be restarted later. In this case, the PWM will resume its opera-
tions where it left off.
34.4.3 Interrupt Sources
The PWM interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using the
PWM interrupt requires the AIC to be programmed first. Note that it is not recommended to use the PWM interrupt
line in edge sensitive mode.
34.5 Functional Description
The PWM macrocell is primarily composed of a clock generator module and 4 channels.
– Clocked by the system clock, MCK, the clock generator module provides 13 clocks.
– Each channel can independently choose one of the clock generator outputs.
– Each channel generates an output waveform with attributes that can be defined independently for each
channel through the user interface registers.
Table 34-1. I/O Line Description
Name Description Type
PWMx PWM Waveform Output for channel x Output
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34.5.1 PWM Clock Generator
Figure 34-2. Functional View of the Clock Generator Block Diagram
Caution: Before using the PWM macrocell, the programmer must first enable the PWM clock in the Power Man-
agement Controller (PMC).
The PWM macrocell master clock, MCK, is divided in the clock generator module to provide different clocks avail-
able for all channels. Each channel can independently select one of the divided clocks.
The clock generator is divided in three blocks:
– a modulo n counter which provides 11 clocks: FMCK, FMCK/2, FMCK/4, FMCK/8, FMCK/16, FMCK/32,
FMCK/64, FMCK/128, FMCK/256, FMCK/512, FMCK/1024
– two linear dividers (1, 1/2, 1/3, ... 1/255) that provide two separate clocks: clkA and clkB
Each linear divider can independently divide one of the clocks of the modulo n counter. The selection of the clock
to be divided is made according to the PREA (PREB) field of the PWM Mode register (PWM_MR). The resulting
clock clkA (clkB) is the clock selected divided by DIVA (DIVB) field value in the PWM Mode register (PWM_MR).
After a reset of the PWM controller, DIVA (DIVB) and PREA (PREB) in the PWM Mode register are set to 0. This
implies that after reset clkA (clkB) are turned off.
modulo n counter
MCK
MCK/2
MCK/4
MCK/16
MCK/32
MCK/64
MCK/8
Divider A clkA
DIVA
PWM_MR
MCK
MCK/128
MCK/256
MCK/512
MCK/1024
PREA
Divider B clkB
DIVB
PWM_MR
PREB
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At reset, all clocks provided by the modulo n counter are turned off except clock “clk”. This situation is also true
when the PWM master clock is turned off through the Power Management Controller.
34.5.2 PWM Channel
34.5.2.1 Block Diagram
Figure 34-3. Functional View of the Channel Block Diagram
Each of the 4 channels is composed of three blocks:
• A clock selector which selects one of the clocks provided by the clock generator described in Section 34.5.1
“PWM Clock Generator” on page 483.
• An internal counter clocked by the output of the clock selector. This internal counter is incremented or
decremented according to the channel configuration and comparators events. The size of the internal counter is
16 bits.
• A comparator used to generate events according to the internal counter value. It also computes the PWMx
output waveform according to the configuration.
34.5.2.2 Waveform Properties
The different properties of output waveforms are:
•the internal clock selection. The internal channel counter is clocked by one of the clocks provided by the clock
generator described in the previous section. This channel parameter is defined in the CPRE field of the
PWM_CMRx register. This field is reset at 0.
•the waveform period. This channel parameter is defined in the CPRD field of the PWM_CPRDx register.
- If the waveform is left aligned, then the output waveform period depends on the counter source clock and can
be calculated:
By using the Master Clock (MCK) divided by an X given prescaler value
(with X being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024), the resulting period formula will be:
By using a Master Clock divided by one of both DIVA or DIVB divider, the formula becomes, respectively:
or
If the waveform is center aligned then the output waveform period depends on the counter source clock and can
be calculated:
By using the Master Clock (MCK) divided by an X given prescaler value
Comparator PWMx
output waveform
Internal
Counter
Clock
Selector
inputs
from clock
generator
inputs from
APB bus
Channel
XCPRD×()
MCK
----------------------------------
CRPD DIVA×()
MCK
---------------------------------------------
CRPD DIVAB×()
MCK
-------------------------------------------------
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(with X being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024). The resulting period formula will be:
By using a Master Clock divided by one of both DIVA or DIVB divider, the formula becomes, respectively:
or
•the waveform duty cycle. This channel parameter is defined in the CDTY field of the PWM_CDTYx register.
If the waveform is left aligned then:
If the waveform is center aligned, then:
•the waveform polarity. At the beginning of the period, the signal can be at high or low level. This property is
defined in the CPOL field of the PWM_CMRx register. By default the signal starts by a low level.
•the waveform alignment. The output waveform can be left or center aligned. Center aligned waveforms can be
used to generate non overlapped waveforms. This property is defined in the CALG field of the PWM_CMRx
register. The default mode is left aligned.
Figure 34-4. Non Overlapped Center Aligned Waveforms
Note: See Figure 34-5 on page 486 for a detailed description of center aligned waveforms.
When center aligned, the internal channel counter increases up to CPRD and.decreases down to 0. This ends the
period.
When left aligned, the internal channel counter increases up to CPRD and is reset. This ends the period.
Thus, for the same CPRD value, the period for a center aligned channel is twice the period for a left aligned
channel.
Waveforms are fixed at 0 when:
• CDTY = CPRD and CPOL = 0
• CDTY = 0 and CPOL = 1
Waveforms are fixed at 1 (once the channel is enabled) when:
• CDTY = 0 and CPOL = 0
• CDTY = CPRD and CPOL = 1
2XCPRD××()
MCK
--------------------------------------------
2CPRD DIVA××()
MCK
-------------------------------------------------------
2CPRD×DIVB×()
MCK
-------------------------------------------------------
duty cycle period 1 fchannel_x_clock CDTY×⁄–()
period
--------------------------------------------------------------------------------------------------------------=
duty cycle period 2⁄()1 fchannel_x_clock CDTY×⁄–())
period 2⁄()
---------------------------------------------------------------------------------------------------------------------------------=
PWM0
PWM1
Period
No overlap
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The waveform polarity must be set before enabling the channel. This immediately affects the channel output level.
Changes on channel polarity are not taken into account while the channel is enabled.
Figure 34-5. Waveform Properties
PWM_MCKx
CHIDx(PWM_SR)
Center Aligned
CPRD(PWM_CPRDx)
CDTY(PWM_CDTYx)
PWM_CCNTx
Output Waveform PWMx
CPOL(PWM_CMRx) = 0
Output Waveform PWMx
CPOL(PWM_CMRx) = 1
CHIDx(PWM_ISR)
Left Aligned
CPRD(PWM_CPRDx)
CDTY(PWM_CDTYx)
PWM_CCNTx
Output Waveform PWMx
CPOL(PWM_CMRx) = 0
Output Waveform PWMx
CPOL(PWM_CMRx) = 1
CHIDx(PWM_ISR)
CALG(PWM_CMRx) = 0
CALG(PWM_CMRx) = 1
Period
Period
CHIDx(PWM_ENA)
CHIDx(PWM_DIS)
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34.5.3 PWM Controller Operations
34.5.3.1 Initialization
Before enabling the output channel, this channel must have been configured by the software application:
• Configuration of the clock generator if DIVA and DIVB are required
• Selection of the clock for each channel (CPRE field in the PWM_CMRx register)
• Configuration of the waveform alignment for each channel (CALG field in the PWM_CMRx register)
• Configuration of the period for each channel (CPRD in the PWM_CPRDx register). Writing in PWM_CPRDx
Register is possible while the channel is disabled. After validation of the channel, the user must use
PWM_CUPDx Register to update PWM_CPRDx as explained below.
• Configuration of the duty cycle for each channel (CDTY in the PWM_CDTYx register). Writing in PWM_CDTYx
Register is possible while the channel is disabled. After validation of the channel, the user must use
PWM_CUPDx Register to update PWM_CDTYx as explained below.
• Configuration of the output waveform polarity for each channel (CPOL in the PWM_CMRx register)
• Enable Interrupts (Writing CHIDx in the PWM_IER register)
• Enable the PWM channel (Writing CHIDx in the PWM_ENA register)
It is possible to synchronize different channels by enabling them at the same time by means of writing simultane-
ously several CHIDx bits in the PWM_ENA register.
• In such a situation, all channels may have the same clock selector configuration and the same period specified.
34.5.3.2 Source Clock Selection Criteria
The large number of source clocks can make selection difficult. The relationship between the value in the Period
Register (PWM_CPRDx) and the Duty Cycle Register (PWM_CDTYx) can help the user in choosing. The event
number written in the Period Register gives the PWM accuracy. The Duty Cycle quantum cannot be lower than
1/PWM_CPRDx value. The higher the value of PWM_CPRDx, the greater the PWM accuracy.
For example, if the user sets 15 (in decimal) in PWM_CPRDx, the user is able to set a value between 1 up to 14 in
PWM_CDTYx Register. The resulting duty cycle quantum cannot be lower than 1/15 of the PWM period.
34.5.3.3 Changing the Duty Cycle or the Period
It is possible to modulate the output waveform duty cycle or period.
To prevent unexpected output waveform, the user must use the update register (PWM_CUPDx) to change wave-
form parameters while the channel is still enabled. The user can write a new period value or duty cycle value in the
update register (PWM_CUPDx). This register holds the new value until the end of the current cycle and updates
the value for the next cycle. Depending on the CPD field in the PWM_CMRx register, PWM_CUPDx either updates
PWM_CPRDx or PWM_CDTYx. Note that even if the update register is used, the period must not be smaller than
the duty cycle.
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Figure 34-6. Synchronized Period or Duty Cycle Update
To prevent overwriting the PWM_CUPDx by software, the user can use status events in order to synchronize his
software. Two methods are possible. In both, the user must enable the dedicated interrupt in PWM_IER at PWM
Controller level.
The first method (polling method) consists of reading the relevant status bit in PWM_ISR Register according to the
enabled channel(s). See Figure 34-7.
The second method uses an Interrupt Service Routine associated with the PWM channel.
Note: Reading the PWM_ISR register automatically clears CHIDx flags.
Figure 34-7. Polling Method
Note: Polarity and alignment can be modified only when the channel is disabled.
PWM_CUPDx Value
PWM_CPRDx PWM_CDTYx
End of Cycle
PWM_CMRx. CPD
User's Writing
10
Writing in PWM_CUPDx
The last write has been taken into account
CHIDx = 1
Writing in CPD field
Update of the Period or Duty Cycle
PWM_ISR Read
Acknowledgement and clear previous register state
YES
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34.5.3.4 Interrupts
Depending on the interrupt mask in the PWM_IMR register, an interrupt is generated at the end of the correspond-
ing channel period. The interrupt remains active until a read operation in the PWM_ISR register occurs.
A channel interrupt is enabled by setting the corresponding bit in the PWM_IER register. A channel interrupt is dis-
abled by setting the corresponding bit in the PWM_IDR register.
34.6 Pulse Width Modulation Controller (PWM) User Interface
Note: 1. Some registers are indexed with “ch_num” index ranging from 0 to X-1.
Table 34-2. Register Mapping
Offset(1) Register Name Access Reset
0x00 PWM Mode Register PWM_MR Read/Write 0
0x04 PWM Enable Register PWM_ENA Write-only -
0x08 PWM Disable Register PWM_DIS Write-only -
0x0C PWM Status Register PWM_SR Read-only 0
0x10 PWM Interrupt Enable Register PWM_IER Write-only -
0x14 PWM Interrupt Disable Register PWM_IDR Write-only -
0x18 PWM Interrupt Mask Register PWM_IMR Read-only 0
0x1C PWM Interrupt Status Register PWM_ISR Read-only 0
0x4C - 0xFC Reserved – – –
0x100 - 0x1FC Reserved
0x200 + ch_num * 0x20 + 0x00 PWM Channel Mode Register PWM_CMR Read/Write 0x0
0x200 + ch_num * 0x20 + 0x04 PWM Channel Duty Cycle Register PWM_CDTY Read/Write 0x0
0x200 + ch_num * 0x20 + 0x08 PWM Channel Period Register PWM_CPRD Read/Write 0x0
0x200 + ch_num * 0x20 + 0x0C PWM Channel Counter Register PWM_CCNT Read-only 0x0
0x200 + ch_num * 0x20 + 0x10 PWM Channel Update Register PWM_CUPD Write-only -
490
SAM7S Series [DATASHEET]
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34.6.1 PWM Mode Register
Register Name: PWM_MR
Access Type: Read/Write
• DIVA, DIVB: CLKA, CLKB Divide Factor
• PREA, PREB
31 30 29 28 27 26 25 24
–––– PREB
23 22 21 20 19 18 17 16
DIVB
15 14 13 12 11 10 9 8
–––– PREA
76543210
DIVA
DIVA, DIVB CLKA, CLKB
0 CLKA, CLKB clock is turned off
1 CLKA, CLKB clock is clock selected by PREA, PREB
2-255 CLKA, CLKB clock is clock selected by PREA, PREB divided by DIVA, DIVB factor.
PREA, PREB Divider Input Clock
0000MCK.
0001MCK/2
0010MCK/4
0011MCK/8
0100MCK/16
0101MCK/32
0110MCK/64
0111MCK/128
1000MCK/256
1001MCK/512
1010MCK/1024
Other Reserved
491
SAM7S Series [DATASHEET]
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34.6.2 PWM Enable Register
Register Name: PWM_ENA
Access Type: Write-only
• CHIDx: Channel ID
0 = No effect.
1 = Enable PWM output for channel x.
34.6.3 PWM Disable Register
Register Name: PWM_DIS
Access Type: Write-only
• CHIDx: Channel ID
0 = No effect.
1 = Disable PWM output for channel x.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
492
SAM7S Series [DATASHEET]
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34.6.4 PWM Status Register
Register Name: PWM_SR
Access Type: Read-only
• CHIDx: Channel ID
0 = PWM output for channel x is disabled.
1 = PWM output for channel x is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
493
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
34.6.5 PWM Interrupt Enable Register
Register Name: PWM_IER
Access Type: Write-only
• CHIDx: Channel ID.
0 = No effect.
1 = Enable interrupt for PWM channel x.
34.6.6 PWM Interrupt Disable Register
Register Name: PWM_IDR
Access Type: Write-only
• CHIDx: Channel ID.
0 = No effect.
1 = Disable interrupt for PWM channel x.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
494
SAM7S Series [DATASHEET]
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34.6.7 PWM Interrupt Mask Register
Register Name: PWM_IMR
Access Type: Read-only
• CHIDx: Channel ID.
0 = Interrupt for PWM channel x is disabled.
1 = Interrupt for PWM channel x is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
495
SAM7S Series [DATASHEET]
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34.6.8 PWM Interrupt Status Register
Register Name: PWM_ISR
Access Type: Read-only
• CHIDx: Channel ID
0 = No new channel period has been achieved since the last read of the PWM_ISR register.
1 = At least one new channel period has been achieved since the last read of the PWM_ISR register.
Note: Reading PWM_ISR automatically clears CHIDx flags.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––CHID3CHID2CHID1CHID0
496
SAM7S Series [DATASHEET]
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34.6.9 PWM Channel Mode Register
Register Name: PWM_CMR[0..X-1]
Access Type: Read/Write
• CPRE: Channel Pre-scaler
• CALG: Channel Alignment
0 = The period is left aligned.
1 = The period is center aligned.
• CPOL: Channel Polarity
0 = The output waveform starts at a low level.
1 = The output waveform starts at a high level.
• CPD: Channel Update Period
0 = Writing to the PWM_CUPDx will modify the duty cycle at the next period start event.
1 = Writing to the PWM_CUPDx will modify the period at the next period start event.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––CPDCPOLCALG
76543210
–––– CPRE
CPRE Channel Pre-scaler
0000MCK
0001MCK/2
0010MCK/4
0011MCK/8
0100MCK/16
0101MCK/32
0110MCK/64
0111MCK/128
1000MCK/256
1001MCK/512
1010MCK/1024
1011CLKA
1100CLKB
Other Reserved
497
SAM7S Series [DATASHEET]
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34.6.10 PWM Channel Duty Cycle Register
Register Name: PWM_CDTY[0..X-1]
Access Type: Read/Write
Only the first 16 bits (internal channel counter size) are significant.
• CDTY: Channel Duty Cycle
Defines the waveform duty cycle. This value must be defined between 0 and CPRD (PWM_CPRx).
31 30 29 28 27 26 25 24
CDTY
23 22 21 20 19 18 17 16
CDTY
15 14 13 12 11 10 9 8
CDTY
76543210
CDTY
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SAM7S Series [DATASHEET]
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34.6.11 PWM Channel Period Register
Register Name: PWM_CPRD[0..X-1]
Access Type: Read/Write
Only the first 16 bits (internal channel counter size) are significant.
• CPRD: Channel Period
If the waveform is left-aligned, then the output waveform period depends on the counter source clock and can be
calculated:
– By using the Master Clock (MCK) divided by an X given prescaler value (with X being 1, 2, 4, 8, 16, 32, 64, 128,
256, 512, or 1024). The resulting period formula will be:
– By using a Master Clock divided by one of both DIVA or DIVB divider, the formula becomes, respectively:
or
If the waveform is center-aligned, then the output waveform period depends on the counter source clock and can be
calculated:
– By using the Master Clock (MCK) divided by an X given prescaler value (with X being 1, 2, 4, 8, 16, 32, 64, 128,
256, 512, or 1024). The resulting period formula will be:
– By using a Master Clock divided by one of both DIVA or DIVB divider, the formula becomes, respectively:
or
31 30 29 28 27 26 25 24
CPRD
23 22 21 20 19 18 17 16
CPRD
15 14 13 12 11 10 9 8
CPRD
76543210
CPRD
XCPRD×()
MCK
----------------------------------
CRPD DIVA×()
MCK
---------------------------------------------
CRPD DIVAB×()
MCK
-------------------------------------------------
2XCPRD××()
MCK
--------------------------------------------
2CPRD DIVA××()
MCK
-------------------------------------------------------
2CPRD×DIVB×()
MCK
-------------------------------------------------------
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SAM7S Series [DATASHEET]
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34.6.12 PWM Channel Counter Register
Register Name: PWM_CCNT[0..X-1]
Access Type: Read-only
• CNT: Channel Counter Register
Internal counter value. This register is reset when:
• the channel is enabled (writing CHIDx in the PWM_ENA register).
• the counter reaches CPRD value defined in the PWM_CPRDx register if the waveform is left aligned.
34.6.13 PWM Channel Update Register
Register Name: PWM_CUPD[0..X-1]
Access Type: Write-only
This register acts as a double buffer for the period or the duty cycle. This prevents an unexpected waveform when modify-
ing the waveform period or duty-cycle.
Only the first 16 bits (internal channel counter size) are significant.
31 30 29 28 27 26 25 24
CNT
23 22 21 20 19 18 17 16
CNT
15 14 13 12 11 10 9 8
CNT
76543210
CNT
31 30 29 28 27 26 25 24
CUPD
23 22 21 20 19 18 17 16
CUPD
15 14 13 12 11 10 9 8
CUPD
76543210
CUPD
CPD (PWM_CMRx Register)
0The duty-cycle (CDTC in the PWM_CDRx register) is updated with the CUPD value at the
beginning of the next period.
1The period (CPRD in the PWM_CPRx register) is updated with the CUPD value at the beginning
of the next period.
500
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501
SAM7S Series [DATASHEET]
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35. USB Device Port (UDP)
35.1 Overview
The USB Device Port (UDP) is compliant with the Universal Serial Bus (USB) V2.0 full-speed device specification.
Each endpoint can be configured in one of several USB transfer types. It can be associated with one or two banks
of a dual-port RAM used to store the current data payload. If two banks are used, one DPR bank is read or written
by the processor, while the other is read or written by the USB device peripheral. This feature is mandatory for iso-
chronous endpoints. Thus the device maintains the maximum bandwidth (1M bytes/s) by working with endpoints
with two banks of DPR.
Suspend and resume are automatically detected by the USB device, which notifies the processor by raising an
interrupt. Depending on the product, an external signal can be used to send a wake up to the USB host controller.
35.2 Block Diagram
Figure 35-1. Block Diagram
Access to the UDP is via the APB bus interface. Read and write to the data FIFO are done by reading and writing
8-bit values to APB registers.
Table 35-1. USB Endpoint Description
Endpoint Number Mnemonic Dual-Bank Max. Endpoint Size Endpoint Type
0 EP0 No 8 Control/Bulk/Interrupt
1 EP1 Yes 64 Bulk/Iso/Interrupt
2 EP2 Yes 64 Bulk/Iso/Interrupt
3 EP3 No 64 Control/Bulk/Interrupt
Atmel Bridge
12 MHz
Suspend/Resume Logic
W
r
a
p
p
e
r
W
r
a
p
p
e
r
U
s
e
r
I
n
t
e
r
f
a
c
e
Serial
Interface
Engine
SIE
MCK
Master Clock
Domain
Dual
Port
RAM
FIFO
UDPCK
Recovered 12 MHz
Domain
udp_int
USB Device
Embedded
USB
Transceiver
DP
DM
external_resume
APB
to
MCU
Bus
txoen
eopn
txd
rxdm
rxd
rxdp
502
SAM7S Series [DATASHEET]
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The UDP peripheral requires two clocks: one peripheral clock used by the Master Clock domain (MCK) and a 48
MHz clock (UDPCK) used by the 12 MHz domain.
A USB 2.0 full-speed pad is embedded and controlled by the Serial Interface Engine (SIE).
The signal external_resume is optional. It allows the UDP peripheral to wake up once in system mode. The host is
then notified that the device asks for a resume. This optional feature must be also negotiated with the host during
the enumeration.
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35.3 Product Dependencies
For further details on the USB Device hardware implementation, see the specific Product Properties document.
The USB physical transceiver is integrated into the product. The bidirectional differential signals DP and DM are
available from the product boundary.
Two I/O lines may be used by the application:
• One to check that VBUS is still available from the host. Self-powered devices may use this entry to be notified
that the host has been powered off. In this case, the board pullup on DP must be disabled in order to prevent
feeding current to the host.
• One to control the board pullup on DP. Thus, when the device is ready to communicate with the host, it activates
its DP pullup through this control line.
35.3.1 I/O Lines
DP and DM are not controlled by any PIO controllers. The embedded USB physical transceiver is controlled by the
USB device peripheral.
To reserve an I/O line to check VBUS, the programmer must first program the PIO controller to assign this I/O in
input PIO mode.
To reserve an I/O line to control the board pullup, the programmer must first program the PIO controller to assign
this I/O in output PIO mode.
35.3.2 Power Management
The USB device peripheral requires a 48 MHz clock. This clock must be generated by a PLL with an accuracy of ±
0.25%.
Thus, the USB device receives two clocks from the Power Management Controller (PMC): the master clock, MCK,
used to drive the peripheral user interface, and the UDPCK, used to interface with the bus USB signals (recovered
12 MHz domain).
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any
read/write operations to the UDP registers including the UDP_TXCV register.
35.3.3 Interrupt
The USB device interface has an interrupt line connected to the Advanced Interrupt Controller (AIC).
Handling the USB device interrupt requires programming the AIC before configuring the UDP.
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35.4 Typical Connection
Figure 35-2. Board Schematic to Interface USB Device Peripheral
35.4.1 USB Device Transceiver
The USB device transceiver is embedded in the product. A few discrete components are required as follows:
• the application detects all device states as defined in chapter 9 of the USB specification;
– pullup enable/disable
–VBUS monitoring
• to reduce power consumption the host is disconnected
• for line termination.
Pullup enable/disable is done through a MOSFET controlled by a PIO. The pullup is enabled when the PIO drives
a 0. Thus PIO default state to 1 corresponds to a pullup disable. Once the pullup is enabled, the host will force a
device reset 100 ms later. Bus powered devices must connect the pullup within 100 ms.
35.4.2 VBUS Monitoring
VBUS monitoring is required to detect host connection. VBUS monitoring is done using a standard PIO with inter-
nal pullup disabled. When the host is switched off, it should be considered as a disconnect, the pullup must be
disabled in order to prevent powering the host through the pull-up resistor.
When the host is disconnected and the transceiver is enabled, then DDP and DDM are floating. This may lead to
over consumption. A solution is to connect 330 KΩ pulldowns on DP and DM. These pulldowns do not alter DDP
and DDM signal integrity.
A termination serial resistor must be connected to DP and DM. The resistor value is defined in the electrical speci-
fication of the product (REXT).
3V3
R
EXT
DDM
DDP
PIO
PIO 27 K
47 K
330 K
Type B
Connector
12
34
5V Bus Monitoring
Pullup Control
R
EXT
330 K
1.5K
0: Enable
1: Disable
505
SAM7S Series [DATASHEET]
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35.5 Functional Description
35.5.1 USB V2.0 Full-speed Introduction
The USB V2.0 full-speed provides communication services between host and attached USB devices. Each device
is offered with a collection of communication flows (pipes) associated with each endpoint. Software on the host
communicates with a USB device through a set of communication flows.
Figure 35-3. Example of USB V2.0 Full-speed Communication Control
The Control Transfer endpoint EP0 is always used when a USB device is first configured (USB v. 2.0 specifications).
35.5.1.1 USB V2.0 Full-speed Transfer Types
A communication flow is carried over one of four transfer types defined by the USB device.
35.5.1.2 USB Bus Transactions
Each transfer results in one or more transactions over the USB bus. There are three kinds of transactions flowing
across the bus in packets:
1. Setup Transaction
2. Data IN Transaction
3. Data OUT Transaction
EP0
USB Host V2.0
Software Client
Data Flow: Control Transfer
EP1
EP2
USB Device 2.0
Data Flow: Isochronous or Bulk In Transfer
Data Flow: Isochronous or Bulk Out Transfer
USB Device endpoint configuration requires that
in the first instance Control Transfer must be EP0.
Table 35-2. USB Communication Flow
Transfer Direction Bandwidth Supported Endpoint Size Error Detection Retrying
Control Bidirectional Not guaranteed 8, 16, 32, 64 Yes Automatic
Isochronous Unidirectional Guaranteed 64 Yes No
Interrupt Unidirectional Not guaranteed ≤ 64 Yes Yes
Bulk Unidirectional Not guaranteed 8, 16, 32, 64 Yes Yes
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35.5.1.3 USB Transfer Event Definitions
As indicated below, transfers are sequential events carried out on the USB bus.
Notes: 1. Control transfer must use endpoints with no ping-pong attributes.
2. Isochronous transfers must use endpoints with ping-pong attributes.
3. Control transfers can be aborted using a stall handshake.
A status transaction is a special type of host-to-device transaction used only in a control transfer. The control trans-
fer must be performed using endpoints with no ping-pong attributes. According to the control sequence (read or
write), the USB device sends or receives a status transaction.
Table 35-3. USB Transfer Events
Control Transfers(1) (3)
• Setup transaction > Data IN transactions > Status
OUT transaction
• Setup transaction > Data OUT transactions > Status
IN transaction
• Setup transaction > Status IN transaction
Interrupt IN Transfer
(device toward host)
• Data IN transaction > Data IN transaction
Interrupt OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction
Isochronous IN Transfer(2)
(device toward host)
• Data IN transaction > Data IN transaction
Isochronous OUT Transfer(2)
(host toward device)
• Data OUT transaction > Data OUT transaction
Bulk IN Transfer
(device toward host)
• Data IN transaction > Data IN transaction
Bulk OUT Transfer
(host toward device)
• Data OUT transaction > Data OUT transaction
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Figure 35-4. Control Read and Write Sequences
Notes: 1. During the Status IN stage, the host waits for a zero length packet (Data IN transaction with no data) from the
device using DATA1 PID. Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0, for more informa-
tion on the protocol layer.
2. During the Status OUT stage, the host emits a zero length packet to the device (Data OUT transaction with no
data).
35.5.2 Handling Transactions with USB V2.0 Device Peripheral
35.5.2.1 Setup Transaction
Setup is a special type of host-to-device transaction used during control transfers. Control transfers must be per-
formed using endpoints with no ping-pong attributes. A setup transaction needs to be handled as soon as possible
by the firmware. It is used to transmit requests from the host to the device. These requests are then handled by the
USB device and may require more arguments. The arguments are sent to the device by a Data OUT transaction
which follows the setup transaction. These requests may also return data. The data is carried out to the host by the
next Data IN transaction which follows the setup transaction. A status transaction ends the control transfer.
When a setup transfer is received by the USB endpoint:
• The USB device automatically acknowledges the setup packet
• RXSETUP is set in the UDP_ CSRx register
• An endpoint interrupt is generated while the RXSETUP is not cleared. This interrupt is carried out to the
microcontroller if interrupts are enabled for this endpoint.
Thus, firmware must detect the RXSETUP polling the UDP_ CSRx or catching an interrupt, read the setup packet
in the FIFO, then clear the RXSETUP. RXSETUP cannot be cleared before the setup packet has been read in the
FIFO. Otherwise, the USB device would accept the next Data OUT transfer and overwrite the setup packet in the
FIFO.
Control Read Setup TX Data OUT TX Data OUT TX
Data Stage
Control Write
Setup Stage
Setup Stage
Setup TX
Setup TX
No Data
Control
Data IN TX Data IN TX
Status Stage
Status Stage
Status IN TX
Status OUT TX
Status IN TX
Data Stage
Setup Stage Status Stage
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SAM7S Series [DATASHEET]
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Figure 35-5. Setup Transaction Followed by a Data OUT Transaction
35.5.2.2 Data IN Transaction
Data IN transactions are used in control, isochronous, bulk and interrupt transfers and conduct the transfer of data
from the device to the host. Data IN transactions in isochronous transfer must be done using endpoints with ping-
pong attributes.
35.5.2.3 Using Endpoints Without Ping-pong Attributes
To perform a Data IN transaction using a non ping-pong endpoint:
1. The application checks if it is possible to write in the FIFO by polling TXPKTRDY in the endpoint’s UDP_
CSRx register (TXPKTRDY must be cleared).
2. The application writes the first packet of data to be sent in the endpoint’s FIFO, writing zero or more byte
values in the endpoint’s UDP_ FDRx register,
3. The application notifies the USB peripheral it has finished by setting the TXPKTRDY in the endpoint’s
UDP_ CSRx register.
4. The application is notified that the endpoint’s FIFO has been released by the USB device when TXCOMP
in the endpoint’s UDP_ CSRx register has been set. Then an interrupt for the corresponding endpoint is
pending while TXCOMP is set.
5. The microcontroller writes the second packet of data to be sent in the endpoint’s FIFO, writing zero or
more byte values in the endpoint’s UDP_ FDRx register,
6. The microcontroller notifies the USB peripheral it has finished by setting the TXPKTRDY in the endpoint’s
UDP_ CSRx register.
7. The application clears the TXCOMP in the endpoint’s UDP_ CSRx.
After the last packet has been sent, the application must clear TXCOMP once this has been set.
TXCOMP is set by the USB device when it has received an ACK PID signal for the Data IN packet. An interrupt is
pending while TXCOMP is set.
Warning: TX_COMP must be cleared after TX_PKTRDY has been set.
Note: Refer to Chapter 8 of the Universal Serial Bus Specification, Rev 2.0, for more information on the Data IN protocol
layer.
RX_Data_BKO
(UDP_CSRx)
ACK
PID
Data OUT
Data OUT
PID
NAK
PID
ACK
PID
Data Setup
Setup
PID
USB
Bus Packets
RXSETUP Flag
Set by USB Device Cleared by Firmware
Set by USB
Device Peripheral
FIFO (DPR)
Content Data Setup Data
XX XX OUT
Interrupt Pending
Setup Received Setup Handled by Firmware Data Out Received
Data OUT
Data OUT
PID
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SAM7S Series [DATASHEET]
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Figure 35-6. Data IN Transfer for Non Ping-pong Endpoint
35.5.2.4 Using Endpoints With Ping-pong Attribute
The use of an endpoint with ping-pong attributes is necessary during isochronous transfer. This also allows han-
dling the maximum bandwidth defined in the USB specification during bulk transfer. To be able to guarantee a
constant or the maximum bandwidth, the microcontroller must prepare the next data payload to be sent while the
current one is being sent by the USB device. Thus two banks of memory are used. While one is available for the
microcontroller, the other one is locked by the USB device.
Figure 35-7. Bank Swapping Data IN Transfer for Ping-pong Endpoints
When using a ping-pong endpoint, the following procedures are required to perform Data IN transactions:
1. The microcontroller checks if it is possible to write in the FIFO by polling TXPKTRDY to be cleared in the
endpoint’s UDP_ CSRx register.
2. The microcontroller writes the first data payload to be sent in the FIFO (Bank 0), writing zero or more byte
values in the endpoint’s UDP_ FDRx register.
USB Bus Packets Data IN 2
Data IN NAK
ACK
Data IN 1
FIFO (DPR)
Content Data IN 2Load In ProgressData IN 1
Cleared by Firmware
DPR access by the firmware
Payload in FIFO
TXCOMP Flag
(UDP_CSRx)
TXPKTRDY Flag
(UDP_CSRx)
PID
Data IN Data IN
PIDPID PIDPID ACK
PID
Prevous Data IN TX Microcontroller Load Data in FIFO Data is Sent on USB Bus
Interrupt
Pending
Interrupt Pending
Set by the firmware Set by the firmware
Cleared by
Firmware
Cleared by Hw
Cleared by Hw
DPR access by the hardware
USB Device USB Bus
Read
Write
Read and Write at the Same Time
1st Data Payload
2nd Data Payload
3rd Data Payload
3rd Data Payload
2nd Data Payload
1st Data Payload
Data IN Packet
Data IN Packet
Data IN Packet
Microcontroller
Endpoint 1
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 1
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SAM7S Series [DATASHEET]
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3. The microcontroller notifies the USB peripheral it has finished writing in Bank 0 of the FIFO by setting the
TXPKTRDY in the endpoint’s UDP_ CSRx register.
4. Without waiting for TXPKTRDY to be cleared, the microcontroller writes the second data payload to be
sent in the FIFO (Bank 1), writing zero or more byte values in the endpoint’s UDP_ FDRx register.
5. The microcontroller is notified that the first Bank has been released by the USB device when TXCOMP in
the endpoint’s UDP_ CSRx register is set. An interrupt is pending while TXCOMP is being set.
6. Once the microcontroller has received TXCOMP for the first Bank, it notifies the USB device that it has
prepared the second Bank to be sent, raising TXPKTRDY in the endpoint’s UDP_ CSRx register.
7. At this step, Bank 0 is available and the microcontroller can prepare a third data payload to be sent.
Figure 35-8. Data IN Transfer for Ping-pong Endpoint
Warning: There is software critical path due to the fact that once the second bank is filled, the driver has to wait for
TX_COMP to set TX_PKTRDY. If the delay between receiving TX_COMP is set and TX_PKTRDY is set too long,
some Data IN packets may be NACKed, reducing the bandwidth.
Warning: TX_COMP must be cleared after TX_PKTRDY has been set.
35.5.2.5 Data OUT Transaction
Data OUT transactions are used in control, isochronous, bulk and interrupt transfers and conduct the transfer of
data from the host to the device. Data OUT transactions in isochronous transfers must be done using endpoints
with ping-pong attributes.
35.5.2.6 Data OUT Transaction Without Ping-pong Attributes
To perform a Data OUT transaction, using a non ping-pong endpoint:
1. The host generates a Data OUT packet.
2. This packet is received by the USB device endpoint. While the FIFO associated to this endpoint is being
used by the microcontroller, a NAK PID is returned to the host. Once the FIFO is available, data are writ-
ten to the FIFO by the USB device and an ACK is automatically carried out to the host.
Data INData IN
Read by USB Device
Read by USB Device
Bank 1
Bank 0
FIFO (DPR)
TXCOMP Flag
(UDP_CSRx) Interrupt Cleared by Firmware
Set by USB
Device
TXPKTRDY Flag
(UDP_MCSRx)
ACK
PID Data IN
PID ACK
PID
Set by Firmware,
Data Payload Written in FIFO Bank 1
Cleared by USB Device,
Data Payload Fully Transmitted
Data IN
PID
USB Bus
Packets
Set by USB Device
Set by Firmware,
Data Payload Written in FIFO Bank 0
Written by
FIFO (DPR)
Microcontroller
Written by
Microcontroller
Written by
Microcontroller
Microcontroller
Load Data IN Bank 0
Microcontroller Load Data IN Bank 1
USB Device Send Bank 0
Microcontroller Load Data IN Bank 0
USB Device Send Bank 1
Interrupt Pending
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3. The microcontroller is notified that the USB device has received a data payload polling RX_DATA_BK0 in
the endpoint’s UDP_ CSRx register. An interrupt is pending for this endpoint while RX_DATA_BK0 is set.
4. The number of bytes available in the FIFO is made available by reading RXBYTECNT in the endpoint’s
UDP_ CSRx register.
5. The microcontroller carries out data received from the endpoint’s memory to its memory. Data received is
available by reading the endpoint’s UDP_ FDRx register.
6. The microcontroller notifies the USB device that it has finished the transfer by clearing RX_DATA_BK0 in
the endpoint’s UDP_ CSRx register.
7. A new Data OUT packet can be accepted by the USB device.
Figure 35-9. Data OUT Transfer for Non Ping-pong Endpoints
An interrupt is pending while the flag RX_DATA_BK0 is set. Memory transfer between the USB device, the FIFO
and microcontroller memory can not be done after RX_DATA_BK0 has been cleared. Otherwise, the USB device
would accept the next Data OUT transfer and overwrite the current Data OUT packet in the FIFO.
35.5.2.7 Using Endpoints With Ping-pong Attributes
During isochronous transfer, using an endpoint with ping-pong attributes is obligatory. To be able to guarantee a
constant bandwidth, the microcontroller must read the previous data payload sent by the host, while the current
data payload is received by the USB device. Thus two banks of memory are used. While one is available for the
microcontroller, the other one is locked by the USB device.
ACK
PID
Data OUTNAK PIDPIDPIDPIDPID Data OUT2ACKData OUT Data OUT 1
USB Bus
Packets
RX_DATA_BK0
Set by USB Device Cleared by Firmware,
Data Payload Written in FIFO
FIFO (DPR)
Content
Written by USB Device Microcontroller Read
Data OUT 1 Data OUT 1 Data OUT 2
Host Resends the Next Data Payload
Microcontroller Transfers Data
Host Sends Data Payload
Data OUT2 Data OUT2
Host Sends the Next Data Payload
Written by USB Device
(UDP_CSRx)
Interrupt Pending
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Figure 35-10. Bank Swapping in Data OUT Transfers for Ping-pong Endpoints
When using a ping-pong endpoint, the following procedures are required to perform Data OUT transactions:
1. The host generates a Data OUT packet.
2. This packet is received by the USB device endpoint. It is written in the endpoint’s FIFO Bank 0.
3. The USB device sends an ACK PID packet to the host. The host can immediately send a second Data
OUT packet. It is accepted by the device and copied to FIFO Bank 1.
4. The microcontroller is notified that the USB device has received a data payload, polling RX_DATA_BK0 in
the endpoint’s UDP_ CSRx register. An interrupt is pending for this endpoint while RX_DATA_BK0 is set.
5. The number of bytes available in the FIFO is made available by reading RXBYTECNT in the endpoint’s
UDP_ CSRx register.
6. The microcontroller transfers out data received from the endpoint’s memory to the microcontroller’s mem-
ory. Data received is made available by reading the endpoint’s UDP_ FDRx register.
7. The microcontroller notifies the USB peripheral device that it has finished the transfer by clearing
RX_DATA_BK0 in the endpoint’s UDP_ CSRx register.
8. A third Data OUT packet can be accepted by the USB peripheral device and copied in the FIFO Bank 0.
9. If a second Data OUT packet has been received, the microcontroller is notified by the flag RX_DATA_BK1
set in the endpoint’s UDP_ CSRx register. An interrupt is pending for this endpoint while RX_DATA_BK1 is
set.
10. The microcontroller transfers out data received from the endpoint’s memory to the microcontroller’s mem-
ory. Data received is available by reading the endpoint’s UDP_ FDRx register.
11. The microcontroller notifies the USB device it has finished the transfer by clearing RX_DATA_BK1 in the
endpoint’s UDP_ CSRx register.
12. A fourth Data OUT packet can be accepted by the USB device and copied in the FIFO Bank 0.
USB Device USB Bus
Read
Write
Write and Read at the Same Time
1st Data Payload
2nd Data Payload
3rd Data Payload
3rd Data Payload
2nd Data Payload
1st Data Payload
Data IN Packet
Data IN Packet
Data IN Packet
Microcontroller
Endpoint 1
Bank 0
Endpoint 1
Bank 1
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 0
Endpoint 1
Bank 1
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Figure 35-11. Data OUT Transfer for Ping-pong Endpoint
Note: An interrupt is pending while the RX_DATA_BK0 or RX_DATA_BK1 flag is set.
Warning: When RX_DATA_BK0 and RX_DATA_BK1 are both set, there is no way to determine which one to clear
first. Thus the software must keep an internal counter to be sure to clear alternatively RX_DATA_BK0 then
RX_DATA_BK1. This situation may occur when the software application is busy elsewhere and the two banks are
filled by the USB host. Once the application comes back to the USB driver, the two flags are set.
35.5.2.8 Stall Handshake
A stall handshake can be used in one of two distinct occasions. (For more information on the stall handshake, refer
to Chapter 8 of the Universal Serial Bus Specification, Rev 2.0.)
• A functional stall is used when the halt feature associated with the endpoint is set. (Refer to Chapter 9 of the
Universal Serial Bus Specification, Rev 2.0, for more information on the halt feature.)
• To abort the current request, a protocol stall is used, but uniquely with control transfer.
The following procedure generates a stall packet:
1. The microcontroller sets the FORCESTALL flag in the UDP_ CSRx endpoint’s register.
2. The host receives the stall packet.
3. The microcontroller is notified that the device has sent the stall by polling the STALLSENT to be set. An
endpoint interrupt is pending while STALLSENT is set. The microcontroller must clear STALLSENT to
clear the interrupt.
When a setup transaction is received after a stall handshake, STALLSENT must be cleared in order to prevent
interrupts due to STALLSENT being set.
A
P
Data OUT PID
ACK Data OUT 3
Data OUT
Data OUT 2
Data OUT
Data OUT 1
PID
Data OUT 3Data OUT 1Data OUT1
Data OUT 2 Data OUT 2
PID PID PID
ACK
Cleared by Firmware
USB Bus
Packets
RX_DATA_BK0 Flag
RX_DATA_BK1 Flag
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 1
FIFO (DPR)
Bank 0
Bank 1
Write by USB Device Write In Progress
Read By Microcontroller
Read By Microcontroller
Set by USB Device,
Data Payload Written
in FIFO Endpoint Bank 0
Host Sends First Data Payload
Microcontroller Reads Data 1 in Bank 0,
Host Sends Second Data Payload
Microcontroller Reads Data2 in Bank 1,
Host Sends Third Data Payload
Cleared by Firmware
Write by USB Device
FIFO (DPR)
(UDP_CSRx)
(UDP_CSRx)
Interrupt Pending
Interrupt Pending
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Figure 35-12. Stall Handshake (Data IN Transfer)
Figure 35-13. Stall Handshake (Data OUT Transfer)
Data IN Stall PIDPID
USB Bus
Packets
Cleared by Firmware
Set by Firmware
FORCESTALL
STALLSENT
Set by
USB Device
Cleared by Firmware
Interrupt Pending
Data OUT PID Stall PID
Data OUT
USB Bus
Packets
Cleared by Firmware
Set by Firmware
FORCESTALL
STALLSENT
Set by USB Device
Interrupt Pending
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35.5.3 Controlling Device States
A USB device has several possible states. Refer to Chapter 9 of the Universal Serial Bus Specification, Rev 2.0.
Figure 35-14. USB Device State Diagram
Movement from one state to another depends on the USB bus state or on standard requests sent through control
transactions via the default endpoint (endpoint 0).
After a period of bus inactivity, the USB device enters Suspend Mode. Accepting Suspend/Resume requests from
the USB host is mandatory. Constraints in Suspend Mode are very strict for bus-powered applications; devices
may not consume more than 500 µA on the USB bus.
While in Suspend Mode, the host may wake up a device by sending a resume signal (bus activity) or a USB device
may send a wake up request to the host, e.g., waking up a PC by moving a USB mouse.
The wake up feature is not mandatory for all devices and must be negotiated with the host.
35.5.3.1 Not Powered State
Self powered devices can detect 5V VBUS using a PIO as described in the typical connection section. When the
device is not connected to a host, device power consumption can be reduced by disabling MCK for the UDP, dis-
abling UDPCK and disabling the transceiver. DDP and DDM lines are pulled down by 330 KΩ resistors.
Attached
Suspended
Suspended
Suspended
Suspended
Hub Reset
or
Deconfigured
Hub
Configured
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Reset
Reset
Address
Assigned
Device
Deconfigured
Device
Configured
Powered
Default
Address
Configured
Power
Interruption
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35.5.3.2 Entering Attached State
When no device is connected, the USB DP and DM signals are tied to GND by 15 KΩ pull-down resistors inte-
grated in the hub downstream ports. When a device is attached to a hub downstream port, the device connects a
1.5 KΩ pull-up resistor on DP. The USB bus line goes into IDLE state, DP is pulled up by the device 1.5 KΩ resistor
to 3.3V and DM is pulled down by the 15 KΩ resistor of the host.
Warning: To write to the UDP_TXVC register, MCK clock must be enabled on the UDP. This is done in the Power
Management Controller.
After pullup connection, the device enters the powered state. In this state, the UDPCK and MCK must be enabled
in the Power Management Controller. The transceiver can remain disabled.
35.5.3.3 From Powered State to Default State
After its connection to a USB host, the USB device waits for an end-of-bus reset. The unmaskable flag END-
BUSRES is set in the register UDP_ISR and an interrupt is triggered.
Once the ENDBUSRES interrupt has been triggered, the device enters Default State. In this state, the UDP soft-
ware must:
• Enable the default endpoint, setting the EPEDS flag in the UDP_CSR[0] register and, optionally, enabling the
interrupt for endpoint 0 by writing 1 to the UDP_IER register. The enumeration then begins by a control transfer.
• Configure the interrupt mask register which has been reset by the USB reset detection
• Enable the transceiver clearing the TXVDIS flag in the UDP_TXVC register.
In this state UDPCK and MCK must be enabled.
Warning: Each time an ENDBUSRES interrupt is triggered, the Interrupt Mask Register and UDP_CSR registers
have been reset.
35.5.3.4 From Default State to Address State
After a set address standard device request, the USB host peripheral enters the address state.
Warning: Before the device enters in address state, it must achieve the Status IN transaction of the control trans-
fer, i.e., the UDP device sets its new address once the TXCOMP flag in the UDP_CSR[0] register has been
received and cleared.
To move to address state, the driver software sets the FADDEN flag in the UDP_GLB_STAT register, sets its new
address, and sets the FEN bit in the UDP_FADDR register.
35.5.3.5 From Address State to Configured State
Once a valid Set Configuration standard request has been received and acknowledged, the device enables end-
points corresponding to the current configuration. This is done by setting the EPEDS and EPTYPE fields in the
UDP_CSRx registers and, optionally, enabling corresponding interrupts in the UDP_IER register.
35.5.3.6 Entering in Suspend State
When a Suspend (no bus activity on the USB bus) is detected, the RXSUSP signal in the UDP_ISR register is set.
This triggers an interrupt if the corresponding bit is set in the UDP_IMR register.This flag is cleared by writing to the
UDP_ICR register. Then the device enters Suspend Mode.
In this state bus powered devices must drain less than 500uA from the 5V VBUS. As an example, the microcon-
troller switches to slow clock, disables the PLL and main oscillator, and goes into Idle Mode. It may also switch off
other devices on the board.
The USB device peripheral clocks can be switched off. Resume event is asynchronously detected. MCK and
UDPCK can be switched off in the Power Management controller and the USB transceiver can be disabled by set-
ting the TXVDIS field in the UDP_TXVC register.
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Warning: Read, write operations to the UDP registers are allowed only if MCK is enabled for the UDP peripheral.
Switching off MCK for the UDP peripheral must be one of the last operations after writing to the and acknowledg-
ing the RXSUSP.
35.5.3.7 Receiving a Host Resume
In suspend mode, a resume event on the USB bus line is detected asynchronously, transceiver and clocks are dis-
abled (however the pullup shall not be removed).
Once the resume is detected on the bus, the WAKEUP signal in the UDP_ISR is set. It may generate an interrupt if
the corresponding bit in the UDP_IMR register is set. This interrupt may be used to wake up the core, enable PLL
and main oscillators and configure clocks.
Warning: Read, write operations to the UDP registers are allowed only if MCK is enabled for the UDP peripheral.
MCK for the UDP must be enabled before clearing the WAKEUP bit in the UDP_ICR register and clearing TXVDIS
in the UDP_TXVC register.
35.5.3.8 Sending a Device Remote Wakeup
In Suspend state it is possible to wake up the host sending an external resume.
• The device must wait at least 5 ms after being entered in suspend before sending an external resume.
• The device has 10 ms from the moment it starts to drain current and it forces a K state to resume the host.
• The device must force a K state from 1 to 15 ms to resume the host
To force a K state to the bus (DM at 3.3V and DP tied to GND), it is possible to use a transistor to connect a pullup
on DM. The K state is obtained by disabling the pullup on DP and enabling the pullup on DM. This should be under
the control of the application.
Figure 35-15. Board Schematic to Drive a K State
3V3
PIO
1.5 K
0: Force Wake UP (K State)
1: Normal Mode
DM
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35.6 USB Device Port (UDP) User Interface
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any read/write
operations to the UDP registers including the UDP_TXCV register.
Notes: 1. Reset values are not defined for UDP_ISR.
2. See Warning above the ”Register Mapping” on this page.
Table 35-4. Register Mapping
Offset Register Name Access Reset
0x000 Frame Number Register UDP_FRM_NUM Read-only 0x0000_0000
0x004 Global State Register UDP_GLB_STAT Read-write 0x0000_0000
0x008 Function Address Register UDP_FADDR Read-write 0x0000_0100
0x00C Reserved – – –
0x010 Interrupt Enable Register UDP_IER Write-only
0x014 Interrupt Disable Register UDP_IDR Write-only
0x018 Interrupt Mask Register UDP_IMR Read-only 0x0000_1200
0x01C Interrupt Status Register UDP_ISR Read-only –(1)
0x020 Interrupt Clear Register UDP_ICR Write-only
0x024 Reserved – – –
0x028 Reset Endpoint Register UDP_RST_EP Read-write
0x02C Reserved – – –
0x030 + 0x4 * (ept_num - 1) Endpoint Control and Status Register UDP_CSR Read-write 0x0000_0000
0x050 + 0x4 * (ept_num - 1) Endpoint FIFO Data Register UDP_FDR Read-write 0x0000_0000
0x070 Reserved – – –
0x074 Transceiver Control Register UDP_TXVC(2) Read-write 0x0000_0000
0x078 - 0xFC Reserved – – –
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35.6.1 UDP Frame Number Register
Register Name: UDP_ FRM_NUM
Access Type: Read-only
• FRM_NUM[10:0]: Frame Number as Defined in the Packet Field Formats
This 11-bit value is incremented by the host on a per frame basis. This value is updated at each start of frame.
Value Updated at the SOF_EOP (Start of Frame End of Packet).
• FRM_ERR: Frame Error
This bit is set at SOF_EOP when the SOF packet is received containing an error.
This bit is reset upon receipt of SOF_PID.
• FRM_OK: Frame OK
This bit is set at SOF_EOP when the SOF packet is received without any error.
This bit is reset upon receipt of SOF_PID (Packet Identification).
In the Interrupt Status Register, the SOF interrupt is updated upon receiving SOF_PID. This bit is set without waiting for
EOP.
Note: In the 8-bit Register Interface, FRM_OK is bit 4 of FRM_NUM_H and FRM_ERR is bit 3 of FRM_NUM_L.
31 30 29 28 27 26 25 24
--- --- --- --- --- --- --- ---
23 22 21 20 19 18 17 16
––––––FRM_OKFRM_ERR
15 14 13 12 11 10 9 8
––––– FRM_NUM
76543210
FRM_NUM
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35.6.2 UDP Global State Register
Register Name: UDP_ GLB_STAT
Access Type: Read-write
This register is used to get and set the device state as specified in Chapter 9 of the USB Serial Bus Specification, Rev.2.0.
• FADDEN: Function Address Enable
Read:
0 = Device is not in address state.
1 = Device is in address state.
Write:
0 = No effect, only a reset can bring back a device to the default state.
1 = Sets device in address state. This occurs after a successful Set Address request. Beforehand, the UDP_ FADDR regis-
ter must have been initialized with Set Address parameters. Set Address must complete the Status Stage before setting
FADDEN. Refer to chapter 9 of the Universal Serial Bus Specification, Rev. 2.0 for more details.
• CONFG: Configured
Read:
0 = Device is not in configured state.
1 = Device is in configured state.
Write:
0 = Sets device in a non configured state
1 = Sets device in configured state.
The device is set in configured state when it is in address state and receives a successful Set Configuration request. Refer
to Chapter 9 of the Universal Serial Bus Specification, Rev. 2.0 for more details.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––CONFGFADDEN
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35.6.3 UDP Function Address Register
Register Name: UDP_ FADDR
Access Type: Read-write
• FADD[6:0]: Function Address Value
The Function Address Value must be programmed by firmware once the device receives a set address request from the
host, and has achieved the status stage of the no-data control sequence. Refer to the Universal Serial Bus Specification,
Rev. 2.0 for more information. After power up or reset, the function address value is set to 0.
• FEN: Function Enable
Read:
0 = Function endpoint disabled.
1 = Function endpoint enabled.
Write:
0 = Disables function endpoint.
1 = Default value.
The Function Enable bit (FEN) allows the microcontroller to enable or disable the function endpoints. The microcontroller
sets this bit after receipt of a reset from the host. Once this bit is set, the USB device is able to accept and transfer data
packets from and to the host.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––––FEN
76543210
–FADD
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35.6.4 UDP Interrupt Enable Register
Register Name: UDP_ IER
Access Type: Write-only
• EP0INT: Enable Endpoint 0 Interrupt
• EP1INT: Enable Endpoint 1 Interrupt
• EP2INT: Enable Endpoint 2Interrupt
• EP3INT: Enable Endpoint 3 Interrupt
0 = No effect.
1 = Enables corresponding Endpoint Interrupt.
• RXSUSP: Enable UDP Suspend Interrupt
0 = No effect.
1 = Enables UDP Suspend Interrupt.
• RXRSM: Enable UDP Resume Interrupt
0 = No effect.
1 = Enables UDP Resume Interrupt.
• SOFINT: Enable Start Of Frame Interrupt
0 = No effect.
1 = Enables Start Of Frame Interrupt.
• WAKEUP: Enable UDP bus Wakeup Interrupt
0 = No effect.
1 = Enables USB bus Interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
– – WAKEUP – SOFINT – RXRSM RXSUSP
76543210
EP3INT EP2INT EP1INT EP0INT
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35.6.5 UDP Interrupt Disable Register
Register Name: UDP_ IDR
Access Type: Write-only
• EP0INT: Disable Endpoint 0 Interrupt
• EP1INT: Disable Endpoint 1 Interrupt
• EP2INT: Disable Endpoint 2 Interrupt
• EP3INT: Disable Endpoint 3 Interrupt
0 = No effect.
1 = Disables corresponding Endpoint Interrupt.
• RXSUSP: Disable UDP Suspend Interrupt
0 = No effect.
1 = Disables UDP Suspend Interrupt.
• RXRSM: Disable UDP Resume Interrupt
0 = No effect.
1 = Disables UDP Resume Interrupt.
• SOFINT: Disable Start Of Frame Interrupt
0 = No effect.
1 = Disables Start Of Frame Interrupt
• WAKEUP: Disable USB Bus Interrupt
0 = No effect.
1 = Disables USB Bus Wakeup Interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
– – WAKEUP – SOFINT – RXRSM RXSUSP
76543210
EP3INT EP2INT EP1INT EP0INT
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35.6.6 UDP Interrupt Mask Register
Register Name: UDP_ IMR
Access Type: Read-only
• EP0INT: Mask Endpoint 0 Interrupt
• EP1INT: Mask Endpoint 1 Interrupt
• EP2INT: Mask Endpoint 2 Interrupt
• EP3INT: Mask Endpoint 3 Interrupt
0 = Corresponding Endpoint Interrupt is disabled.
1 = Corresponding Endpoint Interrupt is enabled.
• RXSUSP: Mask UDP Suspend Interrupt
0 = UDP Suspend Interrupt is disabled.
1 = UDP Suspend Interrupt is enabled.
• RXRSM: Mask UDP Resume Interrupt.
0 = UDP Resume Interrupt is disabled.
1 = UDP Resume Interrupt is enabled.
• SOFINT: Mask Start Of Frame Interrupt
0 = Start of Frame Interrupt is disabled.
1 = Start of Frame Interrupt is enabled.
• BIT12: UDP_IMR Bit 12
Bit 12 of UDP_IMR cannot be masked and is always read at 1
• WAKEUP: USB Bus WAKEUP Interrupt
0 = USB Bus Wakeup Interrupt is disabled.
1 = USB Bus Wakeup Interrupt is enabled.
Note: When the USB block is in suspend mode, the application may power down the USB logic. In this case, any USB HOST resume
request that is made must be taken into account and, thus, the reset value of the RXRSM bit of the register UDP_ IMR is
enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
– – WAKEUP BIT12 SOFINT – RXRSM RXSUSP
76543210
EP3INT EP2INT EP1INT EP0INT
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35.6.7 UDP Interrupt Status Register
Register Name: UDP_ ISR
Access Type: Read-only
• EP0INT: Endpoint 0 Interrupt Status
• EP1INT: Endpoint 1 Interrupt Status
• EP2INT: Endpoint 2 Interrupt Status
• EP3INT: Endpoint 3 Interrupt Status
0 = No Endpoint0 Interrupt pending.
1 = Endpoint0 Interrupt has been raised.
Several signals can generate this interrupt. The reason can be found by reading UDP_ CSR0:
RXSETUP set to 1
RX_DATA_BK0 set to 1
RX_DATA_BK1 set to 1
TXCOMP set to 1
STALLSENT set to 1
EP0INT is a sticky bit. Interrupt remains valid until EP0INT is cleared by writing in the corresponding UDP_ CSR0 bit.
• RXSUSP: UDP Suspend Interrupt Status
0 = No UDP Suspend Interrupt pending.
1 = UDP Suspend Interrupt has been raised.
The USB device sets this bit when it detects no activity for 3ms. The USB device enters Suspend mode.
• RXRSM: UDP Resume Interrupt Status
0 = No UDP Resume Interrupt pending.
1 =UDP Resume Interrupt has been raised.
The USB device sets this bit when a UDP resume signal is detected at its port.
After reset, the state of this bit is undefined, the application must clear this bit by setting the RXRSM flag in the UDP_ ICR
register.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
– – WAKEUP ENDBUSRES SOFINT – RXRSM RXSUSP
76543210
EP3INT EP2INT EP1INT EP0INT
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• SOFINT: Start of Frame Interrupt Status
0 = No Start of Frame Interrupt pending.
1 = Start of Frame Interrupt has been raised.
This interrupt is raised each time a SOF token has been detected. It can be used as a synchronization signal by using
isochronous endpoints.
• ENDBUSRES: End of BUS Reset Interrupt Status
0 = No End of Bus Reset Interrupt pending.
1 = End of Bus Reset Interrupt has been raised.
This interrupt is raised at the end of a UDP reset sequence. The USB device must prepare to receive requests on the end-
point 0. The host starts the enumeration, then performs the configuration.
• WAKEUP: UDP Resume Interrupt Status
0 = No Wakeup Interrupt pending.
1 = A Wakeup Interrupt (USB Host Sent a RESUME or RESET) occurred since the last clear.
After reset the state of this bit is undefined, the application must clear this bit by setting the WAKEUP flag in the UDP_ ICR
register.
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35.6.8 UDP Interrupt Clear Register
Register Name: UDP_ ICR
Access Type: Write-only
• RXSUSP: Clear UDP Suspend Interrupt
0 = No effect.
1 = Clears UDP Suspend Interrupt.
• RXRSM: Clear UDP Resume Interrupt
0 = No effect.
1 = Clears UDP Resume Interrupt.
• SOFINT: Clear Start Of Frame Interrupt
0 = No effect.
1 = Clears Start Of Frame Interrupt.
• ENDBUSRES: Clear End of Bus Reset Interrupt
0 = No effect.
1 = Clears End of Bus Reset Interrupt.
• WAKEUP: Clear Wakeup Interrupt
0 = No effect.
1 = Clears Wakeup Interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
– – WAKEUP ENDBUSRES SOFINT – RXRSM RXSUSP
76543210
––––––––
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35.6.9 UDP Reset Endpoint Register
Register Name: UDP_ RST_EP
Access Type: Read-write
• EP0: Reset Endpoint 0
• EP1: Reset Endpoint 1
• EP2: Reset Endpoint 2
• EP3: Reset Endpoint 3
This flag is used to reset the FIFO associated with the endpoint and the bit RXBYTECOUNT in the register UDP_CSRx.It
also resets the data toggle to DATA0. It is useful after removing a HALT condition on a BULK endpoint. Refer to Chapter
5.8.5 in the USB Serial Bus Specification, Rev.2.0.
Warning: This flag must be cleared at the end of the reset. It does not clear UDP_ CSRx flags.
0 = No reset.
1 = Forces the corresponding endpoint FIF0 pointers to 0, therefore RXBYTECNT field is read at 0 in UDP_ CSRx register.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
EP3 EP2 EP1 EP0
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35.6.10 UDP Endpoint Control and Status Register
Register Name: UDP_ CSRx [x = 0..Y]
Access Type: Read-write
WARNING: Due to synchronization between MCK and UDPCK, the software application must wait for the end of the write
operation before executing another write by polling the bits which must be set/cleared.
//! Clear flags of UDP UDP_CSR register and waits for synchronization
#define Udp_ep_clr_flag(pInterface, endpoint, flags) { \
pInterface->UDP_CSR[endpoint] &= ~(flags); \
while ( (pInterface->UDP_CSR[endpoint] & (flags)) == (flags) ); \
}
//! Set flags of UDP UDP_CSR register and waits for synchronization
#define Udp_ep_set_flag(pInterface, endpoint, flags) { \
pInterface->UDP_CSR[endpoint] |= (flags); \
while ( (pInterface->UDP_CSR[endpoint] & (flags)) != (flags) ); \
}
Note: In a preemptive environment, set or clear the flag and wait for a time of 1 UDPCK clock cycle and 1peripheral clock cycle. How-
ever, RX_DATA_BLK0, TXPKTRDY, RX_DATA_BK1 require wait times of 3 UDPCK clock cycles and 3 peripheral clock cycles
before accessing DPR.
• TXCOMP: Generates an IN Packet with Data Previously Written in the DPR
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Clear the flag, clear the interrupt.
1 = No effect.
Read (Set by the USB peripheral):
0 = Data IN transaction has not been acknowledged by the Host.
1 = Data IN transaction is achieved, acknowledged by the Host.
After having issued a Data IN transaction setting TXPKTRDY, the device firmware waits for TXCOMP to be sure that the
host has acknowledged the transaction.
• RX_DATA_BK0: Receive Data Bank 0
31 30 29 28 27 26 25 24
––––– RXBYTECNT
23 22 21 20 19 18 17 16
RXBYTECNT
15 14 13 12 11 10 9 8
EPEDS – – – DTGLE EPTYPE
76543210
DIR RX_DATA_
BK1
FORCE
STALL TXPKTRDY STALLSENT
ISOERROR RXSETUP RX_DATA_
BK0 TXCOMP
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This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Notify USB peripheral device that data have been read in the FIFO's Bank 0.
1 = To leave the read value unchanged.
Read (Set by the USB peripheral):
0 = No data packet has been received in the FIFO's Bank 0.
1 = A data packet has been received, it has been stored in the FIFO's Bank 0.
When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to
the microcontroller memory. The number of bytes received is available in RXBYTCENT field. Bank 0 FIFO values are read
through the UDP_ FDRx register. Once a transfer is done, the device firmware must release Bank 0 to the USB peripheral
device by clearing RX_DATA_BK0.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• RXSETUP: Received Setup
This flag generates an interrupt while it is set to one.
Read:
0 = No setup packet available.
1 = A setup data packet has been sent by the host and is available in the FIFO.
Write:
0 = Device firmware notifies the USB peripheral device that it has read the setup data in the FIFO.
1 = No effect.
This flag is used to notify the USB device firmware that a valid Setup data packet has been sent by the host and success-
fully received by the USB device. The USB device firmware may transfer Setup data from the FIFO by reading the UDP_
FDRx register to the microcontroller memory. Once a transfer has been done, RXSETUP must be cleared by the device
firmware.
Ensuing Data OUT transaction is not accepted while RXSETUP is set.
• STALLSENT: Stall Sent (Control, Bulk Interrupt Endpoints)/ISOERROR (Isochronous Endpoints)
This flag generates an interrupt while it is set to one.
STALLSENT: This ends a STALL handshake.
Read:
0 = The host has not acknowledged a STALL.
1 = Host has acknowledged the stall.
Write:
0 = Resets the STALLSENT flag, clears the interrupt.
1 = No effect.
This is mandatory for the device firmware to clear this flag. Otherwise the interrupt remains.
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Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL
handshake.
ISOERROR: A CRC error has been detected in an isochronous transfer.
Read:
0 = No error in the previous isochronous transfer.
1 = CRC error has been detected, data available in the FIFO are corrupted.
Write:
0 = Resets the ISOERROR flag, clears the interrupt.
1 = No effect.
• TXPKTRDY: Transmit Packet Ready
This flag is cleared by the USB device.
This flag is set by the USB device firmware.
Read:
0 = Can be set to one to send the FIFO data.
1 = The data is waiting to be sent upon reception of token IN.
Write:
0 = Can be written if old value is zero.
1 = A new data payload is has been written in the FIFO by the firmware and is ready to be sent.
This flag is used to generate a Data IN transaction (device to host). Device firmware checks that it can write a data payload
in the FIFO, checking that TXPKTRDY is cleared. Transfer to the FIFO is done by writing in the UDP_ FDRx register. Once
the data payload has been transferred to the FIFO, the firmware notifies the USB device setting TXPKTRDY to one. USB
bus transactions can start. TXCOMP is set once the data payload has been received by the host.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• FORCESTALL: Force Stall (used by Control, Bulk and Isochronous Endpoints)
Read:
0 = Normal state.
1 = Stall state.
Write:
0 = Return to normal state.
1 = Send STALL to the host.
Refer to chapters 8.4.5 and 9.4.5 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the STALL
handshake.
Control endpoints: During the data stage and status stage, this bit indicates that the microcontroller cannot complete the
request.
Bulk and interrupt endpoints: This bit notifies the host that the endpoint is halted.
The host acknowledges the STALL, device firmware is notified by the STALLSENT flag.
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• RX_DATA_BK1: Receive Data Bank 1 (only used by endpoints with ping-pong attributes)
This flag generates an interrupt while it is set to one.
Write (Cleared by the firmware):
0 = Notifies USB device that data have been read in the FIFO’s Bank 1.
1 = To leave the read value unchanged.
Read (Set by the USB peripheral):
0 = No data packet has been received in the FIFO's Bank 1.
1 = A data packet has been received, it has been stored in FIFO's Bank 1.
When the device firmware has polled this bit or has been interrupted by this signal, it must transfer data from the FIFO to
microcontroller memory. The number of bytes received is available in RXBYTECNT field. Bank 1 FIFO values are read
through UDP_ FDRx register. Once a transfer is done, the device firmware must release Bank 1 to the USB device by
clearing RX_DATA_BK1.
After setting or clearing this bit, a wait time of 3 UDPCK clock cycles and 3 peripheral clock cycles is required before
accessing DPR.
• DIR: Transfer Direction (only available for control endpoints)
Read-write
0 = Allows Data OUT transactions in the control data stage.
1 = Enables Data IN transactions in the control data stage.
Refer to Chapter 8.5.3 of the Universal Serial Bus Specification, Rev. 2.0 for more information on the control data stage.
This bit must be set before UDP_ CSRx/RXSETUP is cleared at the end of the setup stage. According to the request sent
in the setup data packet, the data stage is either a device to host (DIR = 1) or host to device (DIR = 0) data transfer. It is not
necessary to check this bit to reverse direction for the status stage.
• EPTYPE[2:0]: Endpoint Type
• DTGLE: Data Toggle
Read-only
0 = Identifies DATA0 packet.
1 = Identifies DATA1 packet.
Read-write
000 Control
001 Isochronous OUT
101 Isochronous IN
010 Bulk OUT
110 Bulk IN
011 Interrupt OUT
111 Interrupt IN
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Refer to Chapter 8 of the Universal Serial Bus Specification, Rev. 2.0 for more information on DATA0, DATA1 packet
definitions.
• EPEDS: Endpoint Enable Disable
Read:
0 = Endpoint disabled.
1 = Endpoint enabled.
Write:
0 = Disables endpoint.
1 = Enables endpoint.
Control endpoints are always enabled. Reading or writing this field has no effect on control endpoints.
Note: After reset, all endpoints are configured as control endpoints (zero).
• RXBYTECNT[10:0]: Number of Bytes Available in the FIFO
Read-only
When the host sends a data packet to the device, the USB device stores the data in the FIFO and notifies the microcon-
troller. The microcontroller can load the data from the FIFO by reading RXBYTECENT bytes in the UDP_ FDRx register.
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35.6.11 UDP FIFO Data Register
Register Name: UDP_ FDRx [x = 0..Y]
Access Type: Read-write
• FIFO_DATA[7:0]: FIFO Data Value
The microcontroller can push or pop values in the FIFO through this register.
RXBYTECNT in the corresponding UDP_ CSRx register is the number of bytes to be read from the FIFO (sent by the host).
The maximum number of bytes to write is fixed by the Max Packet Size in the Standard Endpoint Descriptor. It can not be
more than the physical memory size associated to the endpoint. Refer to the Universal Serial Bus Specification, Rev. 2.0
for more information.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
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FIFO_DATA
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35.6.12 UDP Transceiver Control Register
Register Name: UDP_ TXVC
Access Type: Read-write
WARNING: The UDP peripheral clock in the Power Management Controller (PMC) must be enabled before any read/write
operations to the UDP registers including the UDP_TXCV register.
• TXVDIS: Transceiver Disable
When UDP is disabled, power consumption can be reduced significantly by disabling the embedded transceiver. This can
be done by setting TXVDIS field.
To enable the transceiver, TXVDIS must be cleared.
NOTE: If the USB pullup is not connected on DP, the user should not write in any UDP register other than the UDP_ TXVC
register. This is because if DP and DM are floating at 0, or pulled down, then SE0 is received by the device with the conse-
quence of a USB Reset.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––– TXVDIS
76543210
––––––––
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36. Analog-to-Digital Converter (ADC)
36.1 Overview
The ADC is based on a Successive Approximation Register (SAR) 10-bit Analog-to-Digital Converter (ADC). It also
integrates an 8-to-1 analog multiplexer, making possible the analog-to-digital conversions of 8 analog lines. The
conversions extend from 0V to ADVREF.
The ADC supports an 8-bit or 10-bit resolution mode, and conversion results are reported in a common register for
all channels, as well as in a channel-dedicated register. Software trigger, external trigger on rising edge of the
ADTRG pin or internal triggers from Timer Counter output(s) are configurable.
The ADC also integrates a Sleep Mode and a conversion sequencer and connects with a PDC channel. These fea-
tures reduce both power consumption and processor intervention.
Finally, the user can configure ADC timings, such as Startup Time and Sample & Hold Time.
36.2 Block Diagram
Figure 36-1. Analog-to-Digital Converter Block Diagram
ADC Interrupt
ADTRG
VDDIN
ADVREF
GND
Trigger
Selection Control
Logic
Successive
Approximation
Register
Analog-to-Digital
Converter
Timer
Counter
Channels
User
Interface
AIC
Peripheral Bridge
APB
PDC
ASB
Dedicated
Analog
Inputs
Analog Inputs
Multiplexed
with I/O lines
AD-
AD-
AD-
PIO
AD-
AD-
AD-
ADC Controller
PMC
MCK
ADC cell
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36.3 Signal Description
36.4 Product Dependencies
36.4.1 Power Management
The ADC Controller clock (MCK) is always clocked.
36.4.2 Interrupt Sources
The ADC interrupt line is connected on one of the internal sources of the Advanced Interrupt Controller. Using the
ADC interrupt requires the AIC to be programmed first.
36.4.3 Analog Inputs
The analog input pins can be multiplexed with PIO lines. In this case, the assignment of the ADC input is automat-
ically done as soon as the corresponding channel is enabled by writing the register ADC_CHER. By default, after
reset, the PIO line is configured as input with its pull-up enabled and the ADC input is connected to the GND.
36.4.4 I/O Lines
The pin ADTRG may be shared with other peripheral functions through the PIO Controller. In this case, the PIO
Controller should be set accordingly to assign the pin ADTRG to the ADC function.
36.4.5 Timer Triggers
Timer Counters may or may not be used as hardware triggers depending on user requirements. Thus, some or all
of the timer counters may be non-connected.
36.4.6 Conversion Performances
For performance and electrical characteristics of the ADC, see the DC Characteristics section.
Table 36-1. ADC Pin Description
Pin Name Description
ADVREF Reference voltage
AD0 - AD7Analog input channels
ADTRG External trigger
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36.5 Functional Description
36.5.1 Analog-to-digital Conversion
The ADC uses the ADC Clock to perform conversions. Converting a single analog value to a 10-bit digital data
requires Sample and Hold Clock cycles as defined in the field SHTIM of the “ADC Mode Register” on page 548 and
10 ADC Clock cycles. The ADC Clock frequency is selected in the PRESCAL field of the Mode Register
(ADC_MR).
The ADC clock range is between MCK/2, if PRESCAL is 0, and MCK/128, if PRESCAL is set to 63 (0x3F). PRES-
CAL must be programmed in order to provide an ADC clock frequency according to the parameters given in the
Product definition section.
36.5.2 Conversion Reference
The conversion is performed on a full range between 0V and the reference voltage pin ADVREF. Analog inputs
between these voltages convert to values based on a linear conversion.
36.5.3 Conversion Resolution
The ADC supports 8-bit or 10-bit resolutions. The 8-bit selection is performed by setting the bit LOWRES in the
ADC Mode Register (ADC_MR). By default, after a reset, the resolution is the highest and the DATA field in the
data registers is fully used. By setting the bit LOWRES, the ADC switches in the lowest resolution and the conver-
sion results can be read in the eight lowest significant bits of the data registers. The two highest bits of the DATA
field in the corresponding ADC_CDR register and of the LDATA field in the ADC_LCDR register read 0.
Moreover, when a PDC channel is connected to the ADC, 10-bit resolution sets the transfer request sizes to 16-bit.
Setting the bit LOWRES automatically switches to 8-bit data transfers. In this case, the destination buffers are
optimized.
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36.5.4 Conversion Results
When a conversion is completed, the resulting 10-bit digital value is stored in the Channel Data Register
(ADC_CDR) of the current channel and in the ADC Last Converted Data Register (ADC_LCDR).
The channel EOC bit in the Status Register (ADC_SR) is set and the DRDY is set. In the case of a connected PDC
channel, DRDY rising triggers a data transfer request. In any case, either EOC and DRDY can trigger an interrupt.
Reading one of the ADC_CDR registers clears the corresponding EOC bit. Reading ADC_LCDR clears the DRDY
bit and the EOC bit corresponding to the last converted channel.
Figure 36-2. EOCx and DRDY Flag Behavior
Conversion Time
Read the ADC_CDRx
EOCx
DRDY
Read the ADC_LCDR
CHx
(ADC_CHSR)
(ADC_SR)
(ADC_SR)
Write the ADC_CR
with START = 1
Conversion Time
Write the ADC_CR
with START = 1
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If the ADC_CDR is not read before further incoming data is converted, the corresponding Overrun Error (OVRE)
flag is set in the Status Register (ADC_SR).
In the same way, new data converted when DRDY is high sets the bit GOVRE (General Overrun Error) in
ADC_SR.
The OVRE and GOVRE flags are automatically cleared when ADC_SR is read.
Figure 36-3. GOVRE and OVREx Flag Behavior
Warning: If the corresponding channel is disabled during a conversion or if it is disabled and then reenabled during
a conversion, its associated data and its corresponding EOC and OVRE flags in ADC_SR are unpredictable.
EOC0
GOVRE
CH0
(ADC_CHSR)
(ADC_SR)
(ADC_SR)
ADTRG
EOC1
CH1
(ADC_CHSR)
(ADC_SR)
OVRE0
(ADC_SR)
Undefined Data Data A Data B
ADC_LCDR
Undefined Data Data A
ADC_CDR0
Undefined Data Data B
ADC_CDR1
Data C
Data C
Conversion
Conversion
Read ADC_SR
DRDY
(ADC_SR)
Read ADC_CDR1
Read ADC_CDR0
Conversion
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36.5.5 Conversion Triggers
Conversions of the active analog channels are started with a software or a hardware trigger. The software trigger is
provided by writing the Control Register (ADC_CR) with the bit START at 1.
The hardware trigger can be one of the TIOA outputs of the Timer Counter channels, or the external trigger input of
the ADC (ADTRG). The hardware trigger is selected with the field TRGSEL in the Mode Register (ADC_MR). The
selected hardware trigger is enabled with the bit TRGEN in the Mode Register (ADC_MR).
If a hardware trigger is selected, the start of a conversion is triggered after a delay starting at each rising edge of
the selected signal. Due to asynchronism handling, the delay may vary in a range of 2 MCK clock periods to 1 ADC
clock period.
If one of the TIOA outputs is selected, the corresponding Timer Counter channel must be programmed in Wave-
form Mode.
Only one start command is necessary to initiate a conversion sequence on all the channels. The ADC hardware
logic automatically performs the conversions on the active channels, then waits for a new request. The Channel
Enable (ADC_CHER) and Channel Disable (ADC_CHDR) Registers enable the analog channels to be enabled or
disabled independently.
If the ADC is used with a PDC, only the transfers of converted data from enabled channels are performed and the
resulting data buffers should be interpreted accordingly.
Warning: Enabling hardware triggers does not disable the software trigger functionality. Thus, if a hardware trigger
is selected, the start of a conversion can be initiated either by the hardware or the software trigger.
36.5.6 Sleep Mode and Conversion Sequencer
The ADC Sleep Mode maximizes power saving by automatically deactivating the ADC when it is not being used for
conversions. Sleep Mode is selected by setting the bit SLEEP in the Mode Register ADC_MR.
The SLEEP mode is automatically managed by a conversion sequencer, which can automatically process the con-
versions of all channels at lowest power consumption.
When a start conversion request occurs, the ADC is automatically activated. As the analog cell requires a start-up
time, the logic waits during this time and starts the conversion on the enabled channels. When all conversions are
complete, the ADC is deactivated until the next trigger. Triggers occurring during the sequence are not taken into
account.
The conversion sequencer allows automatic processing with minimum processor intervention and optimized power
consumption. Conversion sequences can be performed periodically using a Timer/Counter output. The periodic
acquisition of several samples can be processed automatically without any intervention of the processor thanks to
the PDC.
Note: The reference voltage pins always remain connected in normal mode as in sleep mode.
trigger
start
delay
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36.5.7 ADC Timings
Each ADC has its own minimal Startup Time that is programmed through the field STARTUP in the Mode Register
ADC_MR.
In the same way, a minimal Sample and Hold Time is necessary for the ADC to guarantee the best converted final
value between two channels selection. This time has to be programmed through the bitfield SHTIM in the Mode
Register ADC_MR.
Warning: No input buffer amplifier to isolate the source is included in the ADC. This must be taken into consider-
ation to program a precise value in the SHTIM field. See the section, ADC Characteristics in the product datasheet.
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36.6 Analog-to-Digital Converter (ADC) User Interface
Table 36-2. Register Mapping
Offset Register Name Access Reset
0x00 Control Register ADC_CR Write-only –
0x04 Mode Register ADC_MR Read-write 0x00000000
0x08 Reserved – – –
0x0C Reserved – – –
0x10 Channel Enable Register ADC_CHER Write-only –
0x14 Channel Disable Register ADC_CHDR Write-only –
0x18 Channel Status Register ADC_CHSR Read-only 0x00000000
0x1C Status Register ADC_SR Read-only 0x000C0000
0x20 Last Converted Data Register ADC_LCDR Read-only 0x00000000
0x24 Interrupt Enable Register ADC_IER Write-only –
0x28 Interrupt Disable Register ADC_IDR Write-only –
0x2C Interrupt Mask Register ADC_IMR Read-only 0x00000000
0x30 Channel Data Register 0 ADC_CDR0 Read-only 0x00000000
0x34 Channel Data Register 1 ADC_CDR1 Read-only 0x00000000
... ... ... ... ...
0x4C Channel Data Register 7 ADC_CDR7 Read-only 0x00000000
0x50 - 0xFC Reserved – – –
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36.6.1 ADC Control Register
Register Name: ADC_CR
Access Type: Write-only
• SWRST: Software Reset
0 = No effect.
1 = Resets the ADC simulating a hardware reset.
• START: Start Conversion
0 = No effect.
1 = Begins analog-to-digital conversion.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
––––––STARTSWRST
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36.6.2 ADC Mode Register
Register Name: ADC_MR
Access Type: Read/Write
• TRGEN: Trigger Enable
• TRGSEL: Trigger Selection
• LOWRES: Resolution
• SLEEP: Sleep Mode
31 30 29 28 27 26 25 24
–––– SHTIM
23 22 21 20 19 18 17 16
–STARTUP
15 14 13 12 11 10 9 8
PRESCAL
76543210
– – SLEEP LOWRES TRGSEL TRGEN
TRGEN Selected TRGEN
0 Hardware triggers are disabled. Starting a conversion is only possible by software.
1 Hardware trigger selected by TRGSEL field is enabled.
TRGSEL Selected TRGSEL
0 0 0 TIOA Ouput of the Timer Counter Channel 0
0 0 1 TIOA Ouput of the Timer Counter Channel 1
0 1 0 TIOA Ouput of the Timer Counter Channel 2
011Reserved
100Reserved
101Reserved
1 1 0 External trigger
111Reserved
LOWRES Selected Resolution
0 10-bit resolution
1 8-bit resolution
SLEEP Selected Mode
0 Normal Mode
1 Sleep Mode
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• PRESCAL: Prescaler Rate Selection
ADCClock = MCK / ( (PRESCAL+1) * 2 )
• STARTUP: Start Up Time
Startup Time = (STARTUP+1) * 8 / ADCClock
• SHTIM: Sample & Hold Time
Sample & Hold Time = SHTIM/ADCClock
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36.6.3 ADC Channel Enable Register
Register Name: ADC_CHER
Access Type: Write-only
• CHx: Channel x Enable
0 = No effect.
1 = Enables the corresponding channel.
36.6.4 ADC Channel Disable Register
Register Name: ADC_CHDR
Access Type: Write-only
• CHx: Channel x Disable
0 = No effect.
1 = Disables the corresponding channel.
Warning: If the corresponding channel is disabled during a conversion or if it is disabled then reenabled during a conver-
sion, its associated data and its corresponding EOC and OVRE flags in ADC_SR are unpredictable.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
76543210
CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
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CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0
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36.6.5 ADC Channel Status Register
Register Name: ADC_CHSR
Access Type: Read-only
• CHx: Channel x Status
0 = Corresponding channel is disabled.
1 = Corresponding channel is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
––––––––
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CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0
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36.6.6 ADC Status Register
Register Name: ADC_SR
Access Type: Read-only
• EOCx: End of Conversion x
0 = Corresponding analog channel is disabled, or the conversion is not finished.
1 = Corresponding analog channel is enabled and conversion is complete.
• OVREx: Overrun Error x
0 = No overrun error on the corresponding channel since the last read of ADC_SR.
1 = There has been an overrun error on the corresponding channel since the last read of ADC_SR.
• DRDY: Data Ready
0 = No data has been converted since the last read of ADC_LCDR.
1 = At least one data has been converted and is available in ADC_LCDR.
• GOVRE: General Overrun Error
0 = No General Overrun Error occurred since the last read of ADC_SR.
1 = At least one General Overrun Error has occurred since the last read of ADC_SR.
• ENDRX: End of RX Buffer
0 = The Receive Counter Register has not reached 0 since the last write in ADC_RCR or ADC_RNCR.
1 = The Receive Counter Register has reached 0 since the last write in ADC_RCR or ADC_RNCR.
• RXBUFF: RX Buffer Full
0 = ADC_RCR or ADC_RNCR have a value other than 0.
1 = Both ADC_RCR and ADC_RNCR have a value of 0.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––RXBUFFENDRXGOVREDRDY
15 14 13 12 11 10 9 8
OVRE7 OVRE6 OVRE5 OVRE4 OVRE3 OVRE2 OVRE1 OVRE0
76543210
EOC7 EOC6 EOC5 EOC4 EOC3 EOC2 EOC1 EOC0
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36.6.7 ADC Last Converted Data Register
Register Name: ADC_LCDR
Access Type: Read-only
• LDATA: Last Data Converted
The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conver-
sion is completed.
36.6.8 ADC Interrupt Enable Register
Register Name: ADC_IER
Access Type: Write-only
• EOCx: End of Conversion Interrupt Enable x
• OVREx: Overrun Error Interrupt Enable x
• DRDY: Data Ready Interrupt Enable
• GOVRE: General Overrun Error Interrupt Enable
• ENDRX: End of Receive Buffer Interrupt Enable
• RXBUFF: Receive Buffer Full Interrupt Enable
0 = No effect.
1 = Enables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––– LDATA
76543210
LDATA
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––RXBUFFENDRXGOVREDRDY
15 14 13 12 11 10 9 8
OVRE7 OVRE6 OVRE5 OVRE4 OVRE3 OVRE2 OVRE1 OVRE0
76543210
EOC7 EOC6 EOC5 EOC4 EOC3 EOC2 EOC1 EOC0
554
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
36.6.9 ADC Interrupt Disable Register
Register Name: ADC_IDR
Access Type: Write-only
• EOCx: End of Conversion Interrupt Disable x
• OVREx: Overrun Error Interrupt Disable x
• DRDY: Data Ready Interrupt Disable
• GOVRE: General Overrun Error Interrupt Disable
• ENDRX: End of Receive Buffer Interrupt Disable
• RXBUFF: Receive Buffer Full Interrupt Disable
0 = No effect.
1 = Disables the corresponding interrupt.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––RXBUFFENDRXGOVREDRDY
15 14 13 12 11 10 9 8
OVRE7 OVRE6 OVRE5 OVRE4 OVRE3 OVRE2 OVRE1 OVRE0
76543210
EOC7 EOC6 EOC5 EOC4 EOC3 EOC2 EOC1 EOC0
555
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
36.6.10 ADC Interrupt Mask Register
Register Name: ADC_IMR
Access Type: Read-only
• EOCx: End of Conversion Interrupt Mask x
• OVREx: Overrun Error Interrupt Mask x
• DRDY: Data Ready Interrupt Mask
• GOVRE: General Overrun Error Interrupt Mask
• ENDRX: End of Receive Buffer Interrupt Mask
• RXBUFF: Receive Buffer Full Interrupt Mask
0 = The corresponding interrupt is disabled.
1 = The corresponding interrupt is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––RXBUFFENDRXGOVREDRDY
15 14 13 12 11 10 9 8
OVRE7 OVRE6 OVRE5 OVRE4 OVRE3 OVRE2 OVRE1 OVRE0
76543210
EOC7 EOC6 EOC5 EOC4 EOC3 EOC2 EOC1 EOC0
556
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
36.6.11 ADC Channel Data Register
Register Name: ADC_CDRx
Access Type: Read-only
• DATA: Converted Data
The analog-to-digital conversion data is placed into this register at the end of a conversion and remains until a new conver-
sion is completed. The Convert Data Register (CDR) is only loaded if the corresponding analog channel is enabled.
31 30 29 28 27 26 25 24
––––––––
23 22 21 20 19 18 17 16
––––––––
15 14 13 12 11 10 9 8
–––––– DATA
76543210
DATA
557
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37. SAM7S Electrical Characteristics
37.1 Absolute Maximum Ratings
Table 37-1. Absolute Maximum Ratings*
Operating Temperature (Industrial) ...... ..........-40°C to + 85°C*NOTICE: Stresses beyond those listed under “Absolute Maxi-
mum Ratings” may cause permanent damage to
the device. This is a stress rating only and func-
tional operation of the device at these or other con-
ditions beyond those indicated in the operational
sections of this specification is not implied. Expo-
sure to absolute maximum rating conditions for
extended periods may affect device reliability.
Storage Temperature ..... ...............................-60°C to + 150°C
Voltage on Input Pins
with Respect to Ground ..... ..............................-0.3V to + 5.5V
Maximum Operating Voltage
(VDDCORE, and VDDPLL)................. ..............................2.0V
Maximum Operating Voltage
(VDDIO, VDDIN and VDDFLASH)........................................4.0V
Total DC Output Current on all I/O lines
48-lead LQFP/QFN package...........................................100 mA
64-lead LQFP/QFN package...........................................150 mA
558
SAM7S Series [DATASHEET]
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37.2 DC Characteristics
The following characteristics are applicable to the operating temperature range: TA = -40°C to 85°C unless otherwise
specified.
Table 37-2. DC Characteristics
Symbol Parameter Conditions Min Typ Max Units
VVDDCORE DC Supply Core 1.65 1.95 V
VVDDPLL DC Supply PLL 1.65 1.95 V
VVDDIO DC Supply I/Os 3.0 3.6 V
1.65 1.95 V
VVDDFLASH DC Supply Flash 3.0 3.6 V
VIL Input Low-level Voltage VVDDIO from 3.0V to 3.6V -0.3 0.8 V
VVDDIO from 1.65V to 1.95V -0.3 0.45 V
VIH Input High-level Voltage VVDDIO from 3.0V to 3.6V 2.0 5.5 V
VVDDIO from 1.65V to 1.95V 0.6 x VVDDIO 5.5 V
VOL Output Low-level Voltage
IO = 8 mA, VVDDIO from 3.0V to 3.6V 0.4 V
IO = 0.3 mA, (CMOS) VVDDIO from 3.0V to 3.6V 0.1 V
IO = 1.5 mA, VVDDIO from 1.65V to 1.95V 0.2 V
IO = 0.3 mA, (CMOS) VVDDIO from 1.65V to 1.95V 0.1 V
VOH Output High-level Voltage
IO = 8 mA, VVDDIO from 3.0V to 3.6V VDDIO - 0.4 V
IO = 0.3 mA, (CMOS) VVDDIO from 3.0V to 3.6V VDDIO - 0.1 V
IO = 1.5 mA, VVDDIO from 1.65V to 1.95V VDDIO - 0.2 V
IO = 0.3 mA, VVDDIO (CMOS) from 1.65V to 1.95V VDDIO - 0.1 V
ILEAK Input Leakage Current
PA0-PA3, Pull-up resistors disabled
(Typ: TA = 25°C, Max: TA = 85°C) 40 400 nA
Other PIOs, Pull-up resistors disabled
(Typ: TA = 25°C, Max: TA = 85°C) 20 200 nA
IPULLUP Input Pull-up Current
PA17-PA20, VVDDIO from 3.0V to 3.6V,
PAx connected to ground 10 20.6 60 µA
PA17-PA20, VVDDIO from 1.65V to 1.95V,
PAx connected to ground 2.46 5.15 11.5 µA
Other PIOs and NRST, VVDDIO from 3.0V to 3.6V,
PAx connected to ground 143 321 600 µA
Other PIOs and NRST, VVDDIO from 1.65V to 1.95V,
PAx connected to ground 25 75 100 µA
IPULLDOWN
Input Pull-down Current,
(TST, ERASE, JTAGSEL)
VVDDIO from 3.0V to 3.6V,
Pins connected to VVDDIO
135 295 550 µA
VVDDIO from 1.65V to 1.95V,
Pins connected to VVDDIO
30 67 130 µA
CIN Input Capacitance 48 or 64 LQFP Package 13.9 pF
559
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Note that even during startup, VVDDFLASH must always be superior or equal to VVDDCORE.
ISC
Static Current
(SAM7S64/321/32/
161/16)
On VVDDCORE = 1.85V,
MCK = 500Hz TA = 25°C 4.0 15
µA
All inputs driven at 1
(including TMS, TDI, TCK, NRST)
Flash in standby mode
All peripherals off.
TA = 85°C 25 100
ISC Static Current
(SAM7S256/128)
On VVDDCORE = 1.85V,
MCK = 500Hz TA = 25°C 4.0 20
µA
All inputs driven at 1
(including TMS, TDI, TCK, NRST)
Flash in standby mode
All peripherals off
TA = 85°C 35 150
ISC Static Current
(SAM7S512)
On VVDDCORE = 1.85V,
MCK = 500Hz TA = 25°C 6.0 30
µA
All inputs driven at 1
(including TMS, TDI, TCK, NRST)
Flash in standby mode
All peripherals off
TA = 85°C 45 200
IOOutput Current
PA 0 -PA 3 , V VDDIO from 3.0V to 3.6V 16 mA
PA 0 -PA 3 , V VDDIO from 1.65V to 1.95V 3 mA
PA17-PA20, VVDDIO from 3.0V to 3.6V 2 mA
PA17-PA20,VVDDIO from 1.65V to 1.95V 0.5 mA
Other PIOs, VVDDIO from 3.0V to 3.6V 8 mA
Other PIOs, VVDDIO from 1.65V to 1.95V 1.5 mA
TSLOPE Supply Core Slope 6 V/ms
Table 37-3. 1.8V Voltage Regulator Characteristics
Symbol Parameter Conditions Min Typ Max Units
VVDDIN Supply Voltage 3.0 3.3 3.6 V
VVDDOUT Output Voltage IO = 20 mA 1.81 1.85 1.89 V
IVDDIN Current consumption After startup, no load 90 µA
After startup, Idle mode, no load 25 µA
TSTART Startup Time Cload = 2.2 µF, after VDDIN > 2.7V 150 µS
IOMaximum DC Output Current VDDIN = 3.3V 100 mA
IOMaximum DC Output Current VDDIN = 3.3V, in Idle Mode 1 mA
Table 37-2. DC Characteristics (Continued)
560
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.3 Power Consumption
• Typical power consumption of PLLs, Slow Clock and Main Oscillator.
Table 37-4. Brownout Detector Characteristics
Symbol Parameter Conditions Min Typ Max Units
VBOT- Threshold Level Falling edge 1.65 1.68 1.71 V
VHYST Hysteresis VHYST = VBOT+ - VBOT- 50 65 mV
IDD Current Consumption BOD on (GPNVM0 bit active) 12 18 µA
BOD off (GPNVM0 bit inactive) 1 µA
TSTART Startup Time 100 200 µs
Table 37-5. DC Flash Characteristics SAM7S64/321/32/161/16
Symbol Parameter Conditions Min Max Units
TPU Power-up delay 45 µS
ISB Standby current
@25°C
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
4
7µA
@85°C
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
10
30 µA
ICC Active current
Random Read @ 30MHz
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
3.0
0.4 mA
Write
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
400
2.2
µA
mA
Table 37-6. DC Flash Characteristics SAM7S512/256/128
Symbol Parameter Conditions Min Max Units
TPU Power-up delay 45 µS
ISB Standby current
@25°C
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
5
10 µA
@85°C
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
10
120 µA
ICC Active current
Random Read @ 30MHz
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
3.0
0.8 mA
Write
(one bank for SAM7S512)
onto VDDCORE = 1.8V
onto VDDFLASH = 3.3V
400
5.5
µA
mA
561
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• Power consumption of power supply in two different modes: Active and ultra Low-power.
• Power consumption by peripheral: calculated as the difference in current measurement after having enabled
then disabled the corresponding clock.
37.3.1 Power Consumption Versus Modes
The values in Table 37-7 and Table 37-8 on page 566 are measured values of the power consumption with operat-
ing conditions as follows:
•V
DDIO = VDDIN = VDDFLASH= 3.3V
•V
DDCORE = VDDPLL = 1.85V
•T
A = 25°C
• There is no consumption on the I/Os of the device
Figure 37-1. Measure Schematics:
1.8V
VDDIN
Voltage
Regulator
VDDOUT
VDDCORE
VDDPLL
3.3V
VDDIO
VDDFLASH
AMP1
AMP2
562
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
These figures represent the power consumption typically measured on the power supplies..
Table 37-7. Power Consumption for Different Modes
Mode Conditions Consumption Unit
Active, running out of Flash, 8 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 8 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
7.6
4.4 mA
Active, running out of Flash, 8 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated
ARM Core clock is 8 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
8.4
8.2 mA
Active, running out of Flash, 16 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 16 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
12.3
12.1 mA
Active, running out of Flash, 16 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 16 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
13.5
13.3 mA
563
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Active, running out of Flash, 32 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 32 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
19.4
19.2 mA
Active, running out of Flash, 32 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 32 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
20.6
20.4 mA
Active, running out of Flash, 48 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 48 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
27.8
27.6 mA
Active, running out of Flash, 32 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 48 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
29.5
29.3 mA
Table 37-7. Power Consumption for Different Modes
Mode Conditions Consumption Unit
564
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Active, running out of Flash, 50 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 50 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
28.3
28.1 mA
Active, running out of Flash, 50 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 50 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
30.8
30.6 mA
Active, running out of Flash, 55 MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 55 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
31.7
31.5
mA
Active, running out of Flash, 55 MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is read.
PLL is activated.
ARM Core clock is 55 MHz.
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
33.3
33.1 mA
Table 37-7. Power Consumption for Different Modes
Mode Conditions Consumption Unit
565
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Note: 1. “Flash is in standby mode” means the Flash is not accessed at all.
Low power consumption figures found in the above table cannot be guaranteed when accessing the Flash in Ultra
Low Power Mode. In order to meet given low power consumption figures, it is recommended to either stop the pro-
cessor or jump to SRAM.
Active, Running out of SRAM, 1.1MHz
(SAM7S64/321/32/161/16)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is in standby mode.
PLL is de-activated.
Main oscillator is activated.
ARM Core clock is 1.1 MHz.
Running out of SRAM
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
1.12
1.06 mA
Active, Running out of SRAM, 1MHz
(SAM7S512/256/128)
Voltage regulator is on.
Brown Out Detector is activated.
Flash is in standby mode.
PLL is de-activated.
Main oscillator is activated.
ARM Core clock is 1 MHz.
Running out of SRAM
Analog-to-Digital Converter activated.
All peripheral clocks activated.
USB transceiver enabled.
onto AMP1
onto AMP2
1.06
0.99 mA
Ultra low power
Voltage regulator is in Low-power
mode.
Brown Out Detector is de-activated.
Flash is in standby mode.(1)
PLL is de-activated.
Main oscillator is activated.
ARM Core in idle mode.
MCK @ 500Hz.
Analog-to-Digital Converter de-
activated.
All peripheral clocks de-activated.
USB transceiver disabled.
DDM and DDP pins connected to
ground.
onto AMP1
onto AMP2
34.3
4.0 µA
Table 37-7. Power Consumption for Different Modes
Mode Conditions Consumption Unit
566
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.3.2 Peripheral Power Consumption in Active Mode
Note: 1. Note: VDDCORE = 1.85V, TA = 25°C
Table 37-8. Power Consumption on VDDCORE(1)
Peripheral Consumption (Typ) Unit
PIO Controller 12
µA/MHz
USART 28
UDP 20
PWM 16
TWI 5
SPI 16
SSC 32
Timer Counter Channels 6
ARM7TDMI 160
System Peripherals (SAM7S512/256/128) 190
System Peripherals (SAM7S64/321/32/161/16) 140
567
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.4 Crystal Oscillators Characteristics
37.4.1 RC Oscillator Characteristics
Table 37-9. RC Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(tCPRC) RC Oscillator Frequency VDDPLL = 1.65V 22 32 42 kHz
Duty Cycle 45 50 55 %
tST Startup Time VDDPLL = 1.65V 75 µs
IOSC Current Consumption After Startup Time 1.9 µA
568
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.4.2 Main Oscillator Characteristics
Notes: 1. CS is the shunt capacitance.
2. RS = 100-200 Ω; CSHUNT = 2.0 - 2.5 pF; CM = 2 – 1.5 fF (typ, worst case) using 1 K ohm serial resistor on xout.
3. RS = 50-100 Ω; CSHUNT = 2.0 - 2.5 pF; CM = 4 - 3 fF (typ, worst case).
4. RS = 25-50 Ω; CSHUNT = 2.5 - 3.0 pF; CM = 7 -5 fF (typ, worst case).
5. RS = 20-50 Ω; CSHUNT = 3.2 - 4.0 pF; CM = 10 - 8 fF (typ, worst case).
6. CL and CLEXT ∅
Table 37-10. Main Oscillator Characteristics
Symbol Parameter Conditions Min Typ Max Unit
1/(tCPMAIN) Crystal Oscillator Frequency 3 16 20 MHz
CL1, CL2 Internal Load Capacitance (CL1 = CL2)Integrated Load Capacitance
((XIN or XOUT)) 34 40 46 pF
CL (6) Equivalent Load Capacitance Integrated Load Capacitance
(XIN and XOUT in series) 17 20 23 pF
Duty Cycle 30 50 70 %
tST Startup Time
VDDPLL = 1.2 to 2V
CS = 3 pF(1) 1/(tCPMAIN) = 3 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 16 MHz
CS = 7 pF(1) 1/(tCPMAIN) = 20 MHz
14.5
1.4
1
ms
IDDST Standby Current Consumption Standby mode 1 µA
PON Drive level
@3 MHz
@8 MHz
@16 MHz
@20 MHz
15
30
50
50
µW
IDD ON Current dissipation
@3 MHz (2)
@8 MHz (3)
@16 MHz (4)
@20 MHz (5)
150
150
300
400
250
250
450
550
µA
CLEXT (6) Maximum external capacitor
on XIN and XOUT 10 pF
XIN XOUT
CLEXT
CL
CLEXT
SAM7S
569
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.4.3 Crystal Characteristics
37.4.4 XIN Clock Characteristics
Note: 1. These characteristics apply only when the Main Oscillator is in bypass mode (i.e., when MOSCEN = 0 and OSCBYPASS = 1
in the CKGR_MOR register, see the Clock Generator Main Oscillator Register.
Figure 37-2. XIN Clock Timing
Table 37-11. Crystal Characteristics
Symbol Parameter Conditions Min Typ Max Unit
ESR Equivalent Series Resistor Rs
Fundamental @3 MHz
Fundamental @8 MHz
Fundamental @16 MHz
Fundamental @20 MHz
200
100
80
50
W
CMMotional capacitance 8fF
CSHUNT Shunt capacitance 7pF
Table 37-12. XIN Clock Electrical Characteristics
Symbol Parameter Conditions Min Max Units
1/(tCPXIN) XIN Clock Frequency (1) 50.0 MHz
tCPXIN XIN Clock Period (1) 20.0 ns
tCHXIN XIN Clock High Half-period (1) 8.0 ns
tCLXIN XIN Clock Low Half-period (1) 8.0 ns
tCLCH Rise Time (1) 400
tCHCL Fall Time (1) 400
CIN XIN Input Capacitance (1) 46 pF
RIN XIN Pull-down Resistor (1) 500 kΩ
VXIN_IL VXIN Input Low-level Voltage (1) -0.3 0.3 x VDDPLL V
VXIN_IH VXIN Input High-level Voltage (1) 0.7 x VDDPLL 1.95 V
IDDBP Bypass Current Consumption (1) 15 µW/MHz
tCPXIN
tCPXIN
tCPXIN tCHXIN
tCLCH tCHCL
VXIN_IL
VXIN_IH
570
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.5 PLL Characteristics
Note: Startup time depends on PLL RC filter. A calculation tool is provided by Atmel.
37.6 Master Clock Characteristics
37.7 I/O Characteristics
Criteria used to define the maximum frequency of the I/Os:
• output duty cycle (30%-70%)
• minimum output swing: 100mV to VDDIO - 100mV
• Addition of rising and falling time inferior to 75% of the period
Table 37-13. Phase Lock Loop Characteristics
Symbol Parameter Conditions Min Typ Max Unit
FOUT
Output Frequency:
SAM7S64/32/312/161/16 Field out of CKGR_PLL is: 00 80 160 MHz
10 150 200 MHz
FOUT
Output Frequency:
SAM7S512/256/128 Field out of CKGR_PLL is: 00 80 160 MHz
10 150 180 MHz
FIN Input Frequency 1 32 MHz
IPLL Current Consumption Active mode 4 mA
Standby mode 1 µA
Table 37-14. Master Clock Waveform Parameters
Symbol Parameter Conditions Min Max Units
1/(tCPMCK) Master Clock Frequency 55 MHz
Table 37-15. I/O Characteristics
Symbol Parameter Conditions Min Max Units
FreqMaxI01 Pin Group 1 (1) frequency 3.3V domain (4) 12.5 MHz
1.8V domain (5) 4.5 MHz
PulseminHI01 Pin Group 1 (1) High Level Pulse Width 3.3V domain (4) 40 ns
1.8V domain (5) 110 ns
PulseminLI01 Pin Group 1 (1) Low Level Pulse Width 3.3V domain (4) 40 ns
1.8V domain (5) 110 ns
FreqMaxI02 Pin Group 2 (2) frequency 3.3V domain (4) 25 MHz
1.8V domain (5) 14 MHz
PulseminHI02 Pin Group 2 (2) High Level Pulse Width 3.3V domain (4) 20 ns
1.8V domain (5) 36 ns
571
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Notes: 1. Pin Group 1 = PA17 to PA20
2. Pin Group 2 = PA4 to PA16 and PA21 to PA31 (PA21 to PA31 are not present on SAM7S32)
3. Pin Group 3 = PA0 to PA3
4. 3.3V domain: VVDDIO from 3.0V to 3.6V, maximum external capacitor = 40pF
5. 1.8V domain: VVDDIO from 1.65V to 1.95V, maximum external capacitor = 20pF
PulseminLI02 Pin Group 2 (2) Low Level Pulse Width 3.3V domain (4) 20 ns
1.8V domain (5) 36 ns
FreqMaxI03 Pin Group 3 (3) frequency 3.3V domain (4) 30 MHz
1.8V domain (5) 11 MHz
PulseminHI03 Pin Group 3 (3) High Level Pulse Width 3.3V domain (4) 16.6 ns
1.8V domain (5) 45 ns
PulseminLI03 Pin Group 3 (3) Low Level Pulse Width 3.3V domain (4) 16.6 ns
1.8V domain (5) 45 ns
Table 37-15. I/O Characteristics (Continued)
Symbol Parameter Conditions Min Max Units
572
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
37.8 USB Transceiver Characteristics
37.8.1 Electrical Characteristics
37.8.2 Switching Characteristics
Table 37-16. Electrical Parameters
Symbol Parameter Conditions Min Typ Max Unit
Input Levels
VIL Low Level 0.8 V
VIH High Level 2.0 V
VDI Differential Input Sensitivity |(D+) - (D-)| 0.2 V
VCM
Differential Input Common
Mode Range 0.8 2.5 V
CIN Transceiver capacitance Capacitance to ground on each line 9.18 pF
I Hi-Z State Data Line Leakage 0V < VIN < 3.3V -10 +10 µA
REXT
Recommended External USB
Series Resistor In series with each USB pin with ±5% 27 Ω
Output Levels
VOL Low Level Output Measured with RL of 1.425 kOhm tied
to 3.6V 0.0 0.3 V
VOH High Level Output Measured with RL of 14.25 kOhm tied
to GND 2.8 3.6 V
VCRS
Output Signal Crossover
Voltage
Measure conditions described in
Figure 37-3 1.3 2.0 V
Consumption
IVDDIO Current Consumption Transceiver enabled in input mode
DDP=1 and DDM=0
105 200 µA
IVDDCORE Current Consumption 80 150 µA
Table 37-17. In Full Speed
Symbol Parameter Conditions Min Typ Max Unit
tFR Transition Rise Time CLOAD = 50 pF 4 20 ns
tFE Transition Fall Time CLOAD = 50 pF 4 20 ns
tFRFM Rise/Fall time Matching 90 111.11 %
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Figure 37-3. USB Data Signal Rise and Fall Times
10% 10%
90%
VCRS
tRtF
Differential
Data Lines
Rise Time Fall Time
Fosc = 6MHz/750kHz
REXT=27 ohms
Cload
Buffer
(b)
(a)
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37.9 ADC Characteristics
Notes: 1. Corresponds to 13 clock cycles at 5 MHz: 3 clock cycles for track and hold acquisition time and 10 clock cycles for
conversion.
2. Corresponds to 15 clock cycles at 8 MHz: 5 clock cycles for track and hold acquisition time and 10 clock cycles for
conversion.
The user can drive ADC input with impedance up to:
•Z
OUT ≤ (SHTIM -470) x 10 in 8-bit resolution mode
•Z
OUT ≤ (SHTIM -589) x 7.69 in 10-bit resolution mode
with SHTIM (Sample and Hold Time register) expressed in ns and ZOUT expressed in ohms.
Table 37-18. Channel Conversion Time and ADC Clock
Parameter Conditions Min Typ Max Units
ADC Clock Frequency 10-bit resolution mode 5 MHz
ADC Clock Frequency 8-bit resolution mode 8 MHz
Startup Time Return from Idle Mode 20 µs
Track and Hold Acquisition Time 600 ns
Conversion Time ADC Clock = 5 MHz 2 µs
Conversion Time ADC Clock = 8 MHz 1.25 µs
Throughput Rate ADC Clock = 5 MHz 384(1) kSPS
Throughput Rate ADC Clock = 8 MHz 533(2) kSPS
Table 37-19. External Voltage Reference Input
Parameter Conditions Min Typ Max Units
ADVREF Input Voltage Range 2.6 VDDIN V
ADVREF Input Voltage Range 8-bit resolution mode 2.5 VDDIN V
ADVREF Average Current On 13 samples with ADC Clock = 5 MHz 200 250 µA
Current Consumption on VDDIN 0.55 1 mA
Table 37-20. Analog Inputs
Parameter Min Typ Max Units
Input Voltage Range 0V
ADVREF
Input Leakage Current 1µA
Input Capacitance 12 14 pF
Table 37-21. Transfer Characteristics
Parameter Conditions Min Typ Max Units
Resolution 10 Bit
Integral Non-linearity ±2 LSB
Differential Non-linearity No missing code ±1 LSB
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For more information on data converter terminology, please refer to the application note: Data Converter Terminol-
ogy, Atmel lit° 6022.
Offset Error ±2 LSB
Gain Error ±2 LSB
Absolute Accuracy ±4 LSB
Table 37-21. Transfer Characteristics (Continued)
Parameter Conditions Min Typ Max Units
576
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37.10 AC Characteristics
37.10.1 SPI Characteristics
Figure 37-4. SPI Master mode with (CPOL = NCPHA = 0) or (CPOL= NCPHA= 1)
Figure 37-5. SPI Master mode with (CPOL=0 and NCPHA=1) or (CPOL=1 and NCPHA=0)
Figure 37-6. SPI Slave mode with (CPOL=0 and NCPHA=1) or (CPOL=1 and NCPHA=0)
SPCK
MISO
MOSI
SPI2
SPI0SPI1
SPCK
MISO
MOSI
SPI5
SPI3SPI4
SPCK
MISO
MOSI
SPI6
SPI7SPI8
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Figure 37-7. SPI Slave mode with (CPOL = NCPHA = 0) or (CPOL= NCPHA= 1)
Notes: 1. 3.3V domain: VVDDIO from 3.0V to 3.6V, maximum external capacitor = 40 pF.
2. 1.8V domain: VVDDIO from 1.65V to 1.95V, maximum external capacitor = 20 pF.
3. tCPMCK: Master Clock period in ns.
Note that in SPI master mode the ATSAM7S512/256/128/64/321/32 does not sample the data (MISO) on the
opposite edge where data clocks out (MOSI) but the same edge is used as shown in Figure 37-4 and Figure 37-5.
SPCK
MISO
MOSI
SPI9
SPI10 SPI11
Table 37-22. SPI Timings
Symbol Parameter Conditions Min Max Units
SPI0MISO Setup time before SPCK rises (master) 3.3V domain(1) 28.5 + (tCPMCK)/2(3) ns
1.8V domain(2) 38 + (tCPMCK)/2(3) ns
SPI1MISO Hold time after SPCK rises (master) 3.3V domain(1) 0ns
1.8V domain(2) 0ns
SPI2SPCK rising to MOSI Delay (master) 3.3V domain(1) 2ns
1.8V domain(2) 7ns
SPI3MISO Setup time before SPCK falls (master) 3.3V domain(1) 26.5 + (tCPMCK)/2(3) ns
1.8V domain(2) 44 + (tCPMCK)/2(3) ns
SPI4MISO Hold time after SPCK falls (master) 3.3V domain (1) 0ns
1.8V domain (2) 0ns
SPI5SPCK falling to MOSI Delay (master) 3.3V domain (1) 2ns
1.8V domain (2) 2.5 ns
SPI6SPCK falling to MISO Delay (slave) 3.3V domain (1) 28 ns
1.8V domain (2) 44 ns
SPI7MOSI Setup time before SPCK rises (slave) 3.3V domain (1) 2ns
1.8V domain (2) 3ns
SPI8MOSI Hold time after SPCK rises (slave) 3.3V domain (1) 3ns
1.8V domain (2) 2ns
SPI9SPCK rising to MISO Delay (slave) 3.3V domain (1) 28 ns
1.8V domain (2) 43 ns
SPI10 MOSI Setup time before SPCK falls (slave) 3.3V domain (1) 3ns
1.8V domain (2) 3ns
SPI11 MOSI Hold time after SPCK falls (slave) 3.3V domain (1) 3ns
1.8V domain (2) 2ns
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37.10.2 SSC Characteristics
Figure 37-8. SSC Transmitter, TK and TF in output
Figure 37-9. SSC Transmitter, TK in input and TF in output
Figure 37-10. SSC Transmitter, TK in output and TF in input
TK (CKI =1)
TF/TD
SSC0
TK (CKI =0)
TK (CKI =1)
TF/TD
SSC1
TK (CKI =0)
TK (CKI=1)
TF
SSC2
SSC
3
TK (CKI=0)
TD
SSC
4
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Figure 37-11. SSC Transmitter, TK and TF in input
Figure 37-12. SSC Receiver RK and RF in input
Figure 37-13. SSC Receiver, RK in input and RF in output
TK (CKI=0)
TF
SSC
5
SSC
6
TK (CKI=1)
TD
SSC
7
RK (CKI=1)
RF/RD
SSC
8
SSC
9
RK (CKI=0)
RK (CKI=0)
RD
SSC
8
SSC
9
RK (CKI=1)
RF
SSC
10
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Figure 37-14. SSC Receiver, RK and RF in output
Figure 37-15. SSC Receiver, RK in output and RF in input
RK (CKI=0)
RD
SSC
11
SSC
12
RK (CKI=1)
RF
SSC
13
RK (CKI=1)
RF/RD
SSC
11
SSC
12
RK (CKI=0)
Table 37-23. SSC Timings
Symbol Parameter Conditions Min Max Units
Transmitter
SSC0TK edge to TF/TD (TK output, TF output) 3.3V domain 0(2) 12.5(2) ns
1.8V domain 0(2) 31(2) ns
SSC1TK edge to TF/TD (TK input, TF output) 3.3V domain 5.5(2) 29.5(2) ns
1.8V domain 6.5(2) 56(2) ns
SSC2TF setup time before TK edge (TK output) 3.3V domain 17 - tCPMCK ns
1.8V domain 24.5 - tCPMCK ns
SSC3TF hold time after TK edge (TK output) 3.3V domain tCPMCK - 5 ns
1.8V domain tCPMCK - 6 ns
SSC4(1) TK edge to TF/TD (TK output, TF input) 3.3V domain 0 (+2*tCPMCK)(1)(2) 12.5(+2*tCPMCK)(1)(2) ns
1.8V domain 2(+2*tCPMCK)(1)(2) 31(+2*tCPMCK)(1)(2) ns
SSC5TF setup time before TK edge (TK input) 3.3V domain 0 ns
1.8V domain 0 ns
SSC6TF hold time after TK edge (TK input) 3.3V domain tCPMCK ns
1.8V domain tCPMCK ns
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Notes: 1. Timings SSC4 and SSC7 depend on the start condition. When STTDLY = 0 (Receive start delay) and START = 4, or 5 or 7
(Receive Start Selection), two Periods of the MCK must be added to timings.
2. For output signals (TF, TD, RF), Min and Max access times are defined. The Min access time is the time between the TK (or
RK) edge and the signal change. The Max access timing is the time between the TK edge and the signal stabilization. Figure
37-16 illustrates Min and Max accesses for SSC0. The same applies for SSC1, SSC4, and SSC7, SSC10 and SSC13.
3. 3.3V domain: VVDDIOfrom 3.0V to 3.6V, maximum external capacitor = 40 pF.
4. 1.8V domain: VVDDIOfrom 1.65V to 1.95V, maximum external capacitor = 20 pF.
5. tCPMCK: Master Clock period in ns
Figure 37-16. Min and Max access time of output signals
SSC7(1) TK edge to TF/TD (TK input, TF input) 3.3V domain 6 (+3*tCPMCK)(1)(2) 29.5 (+3*tCPMCK)(1)(2) ns
1.8V domain 10 (+3*tCPMCK)(1)(2) 56 (+3*tCPMCK)(1)(2) ns
Receiver
SSC8RF/RD setup time before RK edge (RK input) 3.3V domain 0 ns
1.8V domain 0 ns
SSC9RF/RD hold time after RK edge (RK input) 3.3V domain tCPMCK ns
1.8V domain tCPMCK ns
SSC10 RK edge to RF (RK input) 3.3V domain 6(2) 27(2) ns
1.8V domain 10.5(2) 58(2) ns
SSC11 RF/RD setup time before RK edge (RK output) 3.3V domain 26 - tCPMCK ns
1.8V domain 56.5 - tCPMCK ns
SSC12 RF/RD hold time after RK edge (RK output) 3.3V domain tCPMCK - 10 ns
1.8V domain tCPMCK - 5.5 ns
SSC13 RK edge to RF (RK output) 3.3V domain 0(2) 4(2) ns
1.8V domain 0(2) 12(2) ns
Table 37-23. SSC Timings (Continued)
Symbol Parameter Conditions Min Max Units
TK (CKI =0)
TF/TD
SSC
0min
TK (CKI =1)
SSC
0max
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37.10.3 Embedded Flash Characteristics
The maximum operating frequency is given in Table 37-24 but is limited by the Embedded Flash access time when the pro-
cessor is fetching code out of it. Table 37-24 gives the device maximum operating frequency depending on the FWS field of
the MC_FMR register. This field defines the number of wait states required to access the Embedded Flash Memory.
Notes: 1. FWS = Flash Wait States
2. It is not necessary to use 2 or 3 wait states because the flash can operate at maximum frequency with only 1 wait state.
Table 37-24. Embedded Flash Wait States
FWS(1) Read Operations Maximum Operating Frequency (MHz)
0 1 cycle 30
1 2 cycles 55
2(2) 3 cycles 55
3(2) 4 cycles 55
Table 37-25. AC Flash Characteristics
Parameter Conditions Min Max Units
Program Cycle Time per page including auto-erase 6 ms
per page without auto-erase 3 ms
Full Chip Erase 15 ms
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37.10.4 JTAG/ICE Timings
37.10.4.1 ICE Interface Signals
.
Note: 1. VVDDIO from 3.0V to 3.6V, maximum external capacitor = 40pF
Figure 37-17. ICE Interface Signals
Table 37-26. ICE Interface Timing Specification
Symbol Parameter Conditions Min Max Units
ICE0TCK Low Half-period (1) 51 ns
ICE1TCK High Half-period (1) 51 ns
ICE2TCK Period (1) 102 ns
ICE3TDI, TMS, Setup before TCK High (1) 0ns
ICE4TDI, TMS, Hold after TCK High (1) 3ns
ICE5TDO Hold Time (1) 13 ns
ICE6TCK Low to TDO Valid (1) 20 ns
TCK
ICE
3
ICE
4
ICE
6
TMS/TDI
TDO
ICE
5
ICE
1
ICE
2
ICE
0
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37.10.4.2 JTAG Interface Signals
.
Note: 1. VVDDIO from 3.0V to 3.6V, maximum external capacitor = 40pF
Figure 37-18. JTAG Interface Signals
Table 37-27. JTAG Interface Timing Specification
Symbol Parameter Conditions Min Max Units
JTAG0TCK Low Half-period (1) 6.5 ns
JTAG1TCK High Half-period (1) 5.5 ns
JTAG2TCK Period (1) 12 ns
JTAG3TDI, TMS Setup before TCK High (1) 2ns
JTAG4TDI, TMS Hold after TCK High (1) 3ns
JTAG5TDO Hold Time (1) 4ns
JTAG6TCK Low to TDO Valid (1) 16 ns
JTAG7Device Inputs Setup Time (1) 0ns
JTAG8Device Inputs Hold Time (1) 3ns
JTAG9Device Outputs Hold Time (1) 6ns
JTAG10 TCK to Device Outputs Valid (1) 18 ns
TCK
JTAG9
TMS/TDI
TDO
Device
Outputs
JTAG5
JTAG4
JTAG3
JTAG
0JTAG1
JTAG2
JTAG10
Device
Inputs
JTAG8
JTAG7
JTAG6
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38. Mechanical Characteristics
38.1 Package Drawings
The SAM7S series devices are available in LQFP and QFN package types.
38.2 LQFP Packages
Figure 38-1. 64- and 48-lead LQFP Package Drawing
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Table 38-1. 48-lead LQFP Package Dimensions (in mm)
Symbol Millimeter Inch
Min Nom Max Min Nom Max
A – –1.60– –0.063
A1 0.05 – 0.15 0.002 – 0.006
A2 1.35 1.40 1.45 0.053 0.055 0.057
D 9.00 BSC 0.354 BSC
D1 7.00 BSC 0.276 BSC
E 9.00 BSC 0.354 BSC
E1 7.00 BSC 0.276 BSC
R2 0.08 – 0.20 0.003 – 0.008
R1 0.08 – – 0.003 – –
q 0°3.5°7° 0°3.5°7°
θ10°––0°––
θ211° 12° 13° 11° 12° 13°
θ311° 12° 13° 11° 12° 13°
c 0.09 – 0.20 0.004 – 0.008
L 0.45 0.60 0.75 0.018 0.024 0.030
L1 1.00 REF 0.039 REF
S0.20– –0.008– –
b 0.17 0.20 0.27 0.007 0.008 0.011
e 0.50 BSC. 0.020 BSC.
D2 5.50 0.217
E2 5.50 0.217
Tolerances of Form and Position
aaa 0.20 0.008
bbb 0.20 0.008
ccc 0.08 0.003
ddd 0.08 0.003
587
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This package respects the recommendations of the NEMI User Group.
Table 38-2. 64-lead LQFP Package Dimensions (in mm)
Symbol Millimeter Inch
Min Nom Max Min Nom Max
A – –1.60– –0.063
A1 0.05 – 0.15 0.002 – 0.006
A2 1.35 1.40 1.45 0.053 0.055 0.057
D 12.00 BSC 0.472 BSC
D1 10.00 BSC 0.383 BSC
E 12.00 BSC 0.472 BSC
E1 10.00 BSC 0.383 BSC
R2 0.08 – 0.20 0.003 – 0.008
R1 0.08 – – 0.003 – –
q 0°3.5°7° 0°3.5°7°
θ10°––0°––
θ211° 12° 13° 11° 12° 13°
θ311° 12° 13° 11° 12° 13°
c 0.09 – 0.20 0.004 – 0.008
L 0.45 0.60 0.75 0.018 0.024 0.030
L1 1.00 REF 0.039 REF
S0.20– –0.008– –
b 0.17 0.20 0.27 0.007 0.008 0.011
e 0.50 BSC. 0.020 BSC.
D2 7.50 0.285
E2 7.50 0.285
Tolerances of Form and Position
aaa 0.20 0.008
bbb 0.20 0.008
ccc 0.08 0.003
ddd 0.08 0.003
Table 38-3. Device and LQFP Package Maximum Weight
SAM7S64/321/32/161/16 700 mg
SAM7S512/256/128 750 mg
Table 38-4. LQFP Package Reference
JEDEC Drawing Reference MS-026
JESD97 Classification e3
Table 38-5. LQFP and QFN Package Characteristics
Moisture Sensitivity Level 3
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38.3 QFN Packages
Figure 38-2. 48-pad QFN Package
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Table 38-6. 48-pad QFN Package Dimensions (in mm)
Symbol Millimeter Inch
Min Nom Max Min Nom Max
A – – 090 – – 0.035
A1 – – 0.050 – – 0.002
A2 – 0.65 0.70 – 0.026 0.028
A3 0.20 REF 0.008 REF
b 0.18 0.20 0.23 0.007 0.008 0.009
D 7.00 bsc 0.276 bsc
D2 5.45 5.60 5.75 0.215 0.220 0.226
E 7.00 bsc 0.276 bsc
E2 5.45 5.60 5.75 0.215 0.220 0.226
L 0.35 0.40 0.45 0.014 0.016 0.018
e 0.50 bsc 0.020 bsc
R 0.09 – – 0.004 – –
Tolerances of Form and Position
aaa 0.10 0.004
bbb 0.10 0.004
ccc 0.05 0.002
590
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Figure 38-3. 64-pad QFN Package Drawing
ll dimensions are in mm
eference : JEDEC Drawing MO-220
591
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This package respects the recommendations of the NEMI User Group.
Table 38-7. 64-pad QFN Package Dimensions (in mm)
Symbol Millimeter Inch
Min Nom Max Min Nom Max
A – – 090 – – 0.035
A1 – – 0.05 – – 0.001
A2 – 0.65 0.70 – 0.026 0.028
A3 0.20 REF 0.008 REF
b 0.23 0.25 0.28 0.009 0.010 0.011
D 9.00 bsc 0.354 bsc
D2 6.95 7.10 7.25 0.274 0.280 0.285
E 9.00 bsc 0.354 bsc
E2 6.95 7.10 7.25 0.274 0.280 0.285
L 0.35 0.40 0.45 0.014 0.016 0.018
e 0.50 bsc 0.020 bsc
R 0.125 – – 0.0005 – –
Tolerances of Form and Position
aaa 0.10 0.004
bbb 0.10 0.004
ccc 0.05 0.002
Table 38-8. Device and QFN Package Maximum Weight (Preliminary)
SAM7S32/161/16 200 mg
SAM7S512/256/128/64/321 280 mg
Table 38-9. QFN Package Reference
JEDEC Drawing Reference MO-220
JESD97 Classification e3
Table 38-10. QFN Package Characteristics
Moisture Sensitivity Level 3
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38.4 Soldering Profile
Table 38-11 gives the recommended soldering profile from J-STD-020C.
Note: The package is certified to be backward compatible with Pb/Sn soldering profile.
A maximum of three reflow passes is allowed per component.
Table 38-11. Soldering Profile
Profile Feature Green Package
Average Ramp-up Rate (217°C to Peak) 3°C/sec. max.
Preheat Temperature 175°C ±25°C 180 sec. max.
Temperature Maintained Above 217°C 60 sec. to 150 sec.
Time within 5°C of Actual Peak Temperature 20 sec. to 40 sec.
Peak Temperature Range 260°C
Ramp-down Rate 6°C/sec. max.
Time 25°C to Peak Temperature 8 min. max.
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39. SAM7S Ordering Information
Table 39-1. SAM7S Series Ordering Information
MLR A Ordering
Code
MLR B
Ordering Code
MLR C
Ordering Code
MLR D
Ordering Code Package
Package
Type
Temperature
Operating
Range
AT91SAM7S16-AU
AT91SAM7S16-MU –––
LQFP 48
QFN 48 Green Industrial
(-40
°
C to 85
°
C)
AT91SAM7S161-AU – – – LQFP 64 Green Industrial
(-40
°
C to 85
°
C)
AT91SAM7S32-AU-001
AT91SAM7S32-MU
AT91SAM7S32B-AU
AT91SAM7S32B-MU
LQFP 48
QFN 48 Green Industrial
(-40
°
C to 85
°
C)
AT91SAM7S321-AU
AT91SAM7S321-MU –––
LQFP 64
QFN 64 Green Industrial
(-40
°
C to 85
°
C)
–AT91SAM7S64B-AU
AT91SAM7S64B-MU
AT91SAM7S64C-AU
AT91SAM7S64C-MU – LQFP 64
QFN 64 Green Industrial
(-40
°
C to 85
°
C)
–AT91SAM7S128-AU-001
AT91SAM7S128-MU
AT91SAM7S128C-AU
AT91SAM7S128C-MU
AT91SAM7S128D-AU
AT91SAM7S128D-MU
LQFP 64
QFN 64 Green Industrial
(-40
°
C to 85
°
C)
–AT91SAM7S256-AU-001
AT91SAM7S256-MU
AT91SAM7S256C-AU
AT91SAM7S256C-MU
AT91SAM7S256D-AU
AT91SAM7S256D-MU
LQFP 64
QFN 64 Green Industrial
(-40
°
C to 85
°
C)
AT91SAM7S512-AU
AT91SAM7S512-MU
AT91SAM7S512B-AU
AT91SAM7S512B-MU ––
LQFP 64
QFN 64 Green Industrial
(-40
°
C to 85
°
C)
594
SAM7S Series [DATASHEET]
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595
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40. Errata
40.1 Marking
All devices are marked with the Atmel logo and the ordering code.
Additional marking may be in one of the following formats:
where
• “YY”: manufactory year
• “WW”: manufactory week
• “V”: revision
• “XXXXXXXXX”: lot number
where
• “ZZZZZZ”: manufacturing number
• “YY”: manufactory year
• “WW”: manufactory week
• “XXXXXXXXX”: lot number
YYWW V
XXXXXXXXX ARM
ZZZZZZ YYWW
XXXXXXXXX ARM
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SAM7S Series [DATASHEET]
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40.2 Errata Summary by Product and Revision or Manufacturing Number
Table 40-1. Errata Summary Table
SAM7Sx Product
Revision or Manufacturing Number
Errata
SAM7S512 rev A
SAM7S512 rev B
SAM7S256/128 58818C
SAM7S256/128 rev A
SAM7S256/128 rev B
SAM7S256/128 rev C
SAM7S256/128 rev D
SAM7S64/32 58814G
SAM7S64 rev A
SAM7S64 rev B
SAM7S64 rev C
SAM7S32 rev A
SAM7S32 rev B
SAM7S321 rev A
SAM7S161 rev A
SAM7S16 rev A
Part
Chip ID Wrong Chip ID Value XX
ADC DRDY Bit Cleared XXXXX XXX X X X
ADC DRDY not Cleared on Disable XXXXX XXX X X X
ADC DRDY Possibly Skipped due to CDR Read XXXXX XXX X X X
ADC Possible Skip on DRDY when Disabling a Channel XXXXX XXX X X X
ADC GOVRE Bit is not Updated XXXXX XXX X X X
ADC GOVRE Bit is not Set when Reading CDR XXXXX XXX X X X
ADC GOVRE Bit is not Set when Disabling a Channel XXXXX XXX X X X
ADC OVRE Flag Behavior XXXXX XXX X X X
ADC EOC Set although Channel Disabled XXXXX XXX X X X
ADC Spurious Clear of EOC Flag XXXXX XXX X X X
ADC Sleep Mode XXXXX XXX X X X
EFC Embedded Flash Access Time 1 XXX
Embedded Flash Access Time 2 X
JTAG Recommendation for TDI Pin X
MCK Limited Master Clock Frequency Ranges XX
NVM Bits Write/Erase Cycles Number XXX XXX X
PIO Leakage on PA17 - PA20 XXXX XX X
PIO Electrical Characteristics on NRST and PA0-PA16 and
PA21-31 XXXXXXXXXXX X X
PIO Drive Low NRST, PA0-PA16 and PA21-PA31 XXXXXXXXXXX X X
PMC Slow Clock Selected in PMC and a Transition Occurs on
PA 1 XX
PMC Programming CSS in PMC_MCKR Register XX
PWM Update when PWM_CCNTx = 0 or 1 XXXXXXXXXXX X X X
PWM Update when PWM_CPRDx = 0 XXXXXXXXXXX X X X
PWM Counter Start Value XXXXXXXXXXX X X X
PWM Constraints on Duty Cycle Value XXXXX XXX X X X
PWM Behavior of CHIDx Status Bits in the PWM_SR Register XXXXX XXX X X X
RTT Possible Event Loss when Reading RTT_SR XXXXXXXXX X X X
RTT RTT_VR May be Corrupted XX
SPI Software Reset Must be Written Twice XX X X X
SPI Pulse Generation on SPCK XXX X X
SPI Bad Behavior when CSAAT = 1 and SCBR = 1 XXXXX XXX X X
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40.3 Errata Organization by Product and Revision or Manufacturing Number
“SAM7S512 Errata - Revision A Parts” on page 599
“SAM7S512 Errata - Revision B Parts” on page 606
“SAM7S256 Errata - Manufacturing Number 58818C” on page 614
“SAM7S256 Errata - Revision A Parts” on page 624
SPI LASTXFER (Last Transfer) behavior XXXXX XXX X X
SPI SPCK Behavior in Master Mode XXXXX XXX X X
SPI Chip Select and Fixed Mode XXXXX XXX X X
SPI Baudrate Set to 1 XXXXX XXX X X
SPI Disable In Slave Mode XXXXX XXX X X
SPI Disable Issue XXX X X
SPI Software Reset and SPIEN Bit XXX X X
SPI CSAAT = 1 and Delay XXX X X
SPI Bad Serial Clock Generation on 2nd Chip Select XXXXX XXX X X X
SSC Periodic Transmission Limitations in Master Mode XXXXX XXX X X X
SSC Transmitter Limitations in Slave Mode XXXXX XXX X X X
SSC Transmitter Limitations in Slave Mode XXXXX XXX X X X
TWI Clock Divider XXXXX XXX X X
TWI Software Reset XXXXX XXX X X
TWI Disabling Does not Operate Correctly XXXXX XXX X X
TWI NACK Status Bit Lost XXXXX XXX X X
TWI Possible Receive Holding Register Corruption XXXXX XXX X X
USART Hardware Handshake XXX X X
USART CTS in Hardware Handshaking XXXXX XXX X X
USART Hardware Handshaking – Two Characters Sent XXXXX XXX X X
USART XOFF Character Bad Behavior XXXXX XXX X X
USART RXBRK Flag Error in Asynchronous Mode XXXXX
USART DCD is active High instead of Low XXXXXXXXXX X X X
Voltage
Regulator Current Consumption in Deep Mode XXX XXX X
Voltage
Regulator Load Versus Temperature XXX XXX X
WDT The Watchdog Timer May Lock the Device in a Reset
State XX
WDT The Watchdog Timer Status Register and Interrupt XX
Table 40-1. Errata Summary Table (Continued)
SAM7Sx Product
Revision or Manufacturing Number
Errata
SAM7S512 rev A
SAM7S512 rev B
SAM7S256/128 58818C
SAM7S256/128 rev A
SAM7S256/128 rev B
SAM7S256/128 rev C
SAM7S256/128 rev D
SAM7S64/32 58814G
SAM7S64 rev A
SAM7S64 rev B
SAM7S64 rev C
SAM7S32 rev A
SAM7S32 rev B
SAM7S321 rev A
SAM7S161 rev A
SAM7S16 rev A
Part
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“SAM7S256 Errata - Revision B Parts” on page 634
“SAM7S256 Errata - Revision C Parts” on page 642
“SAM7S256 Errata - Revision D Parts” on page 644
“SAM7S128 Errata - Manufacturing Number 58818C” on page 646
“SAM7S128 Errata - Revision A Parts” on page 656
“SAM7S128 Errata - Revision B Parts” on page 666
“SAM7S128 Errata - Revision C Parts” on page 674
“SAM7S128 Errata - Revision D Parts” on page 676
“SAM7S64 Errata - Manufacturing Number 58814G” on page 678
“SAM7S64 Errata - Revision A Parts” on page 688
“SAM7S64 Errata - Revision B Parts” on page 697
“SAM7S64 Errata - Revision C Parts” on page 706
“SAM7S321 Errata - Revision A Parts” on page 708
“SAM7S32 Errata - Manufacturing Number 58814G” on page 716
“SAM7S32 Errata - Revision A Parts” on page 725
“SAM7S32 Errata - Revision B Parts” on page 734
“SAM7S161 Errata - Revision A Parts” on page 742
“SAM7S16 Errata - Revision A Parts” on page 747
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40.4 SAM7S512 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S512 Revision A chip ID is: 0x270B 0A40.
40.4.1 Analog-to-Digital Converter (ADC)
40.4.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.4.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.4.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.4.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.4.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.4.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.4.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.4.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.4.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.4.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.4.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.4.2 Embedded Flash Controller (EFC)
40.4.2.1 EFC: Embedded Flash Access Time 1
The embedded Flash maximum access time is 20 MHz (instead of 30 MHz) at zero Wait State (FWS = 0).
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The maximum operating frequency with one Wait State (FWS = 1) is 48.1 MHz (instead of 55 MHz). Above 48.1
MHz and until 55 MHz, two Wait States (FWS = 2) are required.
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.4.3 Parallel Input/Output Controller (PIO)
40.4.3.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.4.3.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.4.3.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.4.4 Pulse Width Modulation Controller (PWM)
40.4.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.4.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.4.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.4.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.4.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.4.5 Real Time Timer (RTT)
40.4.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.4.6 Serial Peripheral Interface (SPI)
40.4.6.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRST in the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select).
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.4.6.2 SPI: Bad tx_ready Behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
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40.4.6.3 SPI: LASTXFER (Last Transfer) Behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.4.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.4.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.4.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.4.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.4.6.8 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
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Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.4.7 Synchronous Serial Controller (SSC)
40.4.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.4.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.4.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly. In the following schematic, TD, TK
and NRST are SAM7S signals, TXD is the delayed data to connect to the device.
40.4.8 Two-wire Interface (TWI)
40.4.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
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None.
40.4.8.2 TWI: Software Reset
when a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new transfer
in READ or WRITE mode.
Problem Fix/Workaround
None.
40.4.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.4.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.4.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.4.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.4.9.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes high near the end of the start bit, a character can be lost.
CTS must not go high during a time slot occurring between 2 Master Clock periods before and 16 Master Clock
periods after the rising edge of the start bit.
Problem Fix/Workaround
None.
40.4.9.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
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40.4.9.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.4.9.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.4.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.5 SAM7S512 Errata - Revision B Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S512 Revision B chip ID is: 0x270B 0A4F.
40.5.1 Analog-to-Digital Converter (ADC)
40.5.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.5.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.5.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
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40.5.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.5.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.5.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.5.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.5.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.5.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
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Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.5.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.5.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.5.2 Embedded Flash Controller (EFC)
40.5.2.1 EFC: Embedded Flash Access Time 2
The Flash memory access time has been reduced as per the table below:
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.5.3 Parallel Input/Output Controller (PIO)
40.5.3.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
Flash Wait
State (FWS)
Read
Operations
Maximum Operating
Frequency (MHz)
0 1 cycle 16
1 2 cycles 32
2 3 cycles 48
3 4 cycles 55
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40.5.3.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.5.3.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.5.4 Pulse Width Modulation Controller (PWM)
40.5.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.5.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.5.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.5.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.5.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.5.5 Real Time Timer (RTT)
40.5.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.5.6 Serial Peripheral Interface (SPI)
40.5.6.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRST in the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select).
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.5.6.2 SPI: Bad tx_ready Behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.5.6.3 SPI: LASTXFER (Last Transfer) Behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.5.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
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40.5.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.5.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.5.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.5.6.8 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.5.7 Synchronous Serial Controller (SSC)
40.5.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
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40.5.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.5.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly. In the following schematic, TD, TK
and NRST are SAM7S signals, TXD is the delayed data to connect to the device.
40.5.8 Two-wire Interface (TWI)
40.5.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.5.8.2 TWI: Software Reset
when a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new transfer
in READ or WRITE mode.
Problem Fix/Workaround
None.
40.5.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
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Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.5.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.5.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.5.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.5.9.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes high near the end of the start bit, a character can be lost.
CTS must not go high during a time slot occurring between 2 Master Clock periods before and 16 Master Clock
periods after the rising edge of the start bit.
Problem Fix/Workaround
None.
40.5.9.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.5.9.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.5.9.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
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The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.5.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.6 SAM7S256 Errata - Manufacturing Number 58818C
Refer to Section 40.1 “Marking” on page 595.
Important: Section 40.6.14.1 ”WDT: The Watchdog Timer May Lock the Device in a Reset State”
40.6.1 Chip ID
40.6.1.1 Wrong Chip ID Value
The Chip ID is 0x270D0940 instead of 0x270B0940.
Problem Fix/Workaround
None.
40.6.2 Analog-to-Digital Converter (ADC)
40.6.2.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.6.2.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.6.2.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.6.2.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
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40.6.2.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.6.2.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.6.2.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.6.2.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.6.2.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
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40.6.2.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.6.2.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.6.3 Master Clock (MCK)
40.6.3.1 MCK: Limited Master Clock Frequency Ranges
If the Flash is operating without wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with one wait state, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with two wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 25 MHz.
If the Flash is operating with three wait states, the frequency of the Master Clock MCK must be lower than 3 MHz
or higher than 38 MHz.
If these constraints are not respected, the correct operation of the system cannot be guaranteed and either data or
prefetch abort might occur.
The maximum operating frequencies (at 30 MHz @ 0 Wait States and 55 MHz @ 1 Wait State) as stated in
Table 37-24, “Embedded Flash Wait States,” on page 582, are still applicable.
Note: It is not necessary to use 2 o 3 wait states because the Flash can operate at maximum frequency with only 1 wait state.
Problem Fix/Workaround
The user must ensure that the device is running at the authorized frequency by programming the PLL properly to
not run within the forbidden frequency range.
40.6.4 Non Volatile Memory Bits (NVM Bits)
40.6.4.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 256 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
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40.6.5 Parallel Input/Output Controller (PIO)
40.6.5.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.6.5.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.6.5.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.6.6 Power Management Controller (PMC)
40.6.6.1 PMC: Slow Clock Selected in PMC and a Transition Occurs on PA1
Under certain rare circumstances, when CSS = 00 in PMC_MCKR, and PA1 is set as an input and a transition
occurs on PA1, device malfunction might occur.
Problem Fix/Workaround
Do not transition PA1 as an input when CSS = 00 in PMC_MCKR.
40.6.6.2 PMC: Programming CSS in PMC_MCKR Register
Under certain rare circumstances, reprogramming the CSS value in the PMC_MCKR register (i.e switching the
main clock source) might generate malfunction of the device if the following two actions occur simultaneously.
1. Switching from:
– PLL Clock to Slow Clock or
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
And
2. Program code is being executed out of flash, or a transition is occurring on PA1, either as an input or
output.
Note: This issue does not occur when transitioning from slow clock to main clock or from slow clock to PLL clock.
Problem Fix/Workaround
When changing CSS in the PMC_MCKR to switch from
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
Ensure that the processor is executing out of SRAM and ensure no transition occurs on PA1, either as an input or
output, starting from writing to the PMC_MCKR register until MCKRDY = 1.
40.6.7 Pulse Width Modulation Controller (PWM)
40.6.7.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.6.7.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.6.7.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.6.7.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.6.7.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
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Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.6.8 Real Time Timer (RTT)
40.6.8.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.6.8.2 RTT: RTT_VR May be Corrupted
Under certain rare circumstances, the Real-time Timer Value (RTT_VR) may be corrupted.
Problem Fix/Workaround
Use RTTINC as an increment for a software counter.
40.6.9 Serial Peripheral Interface (SPI)
40.6.9.1 SPI: Bad tx_ready Behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.6.9.2 SPI: LASTXFER (Last Transfer) Behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.6.9.3 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.6.9.4 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
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40.6.9.5 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.6.9.6 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.6.9.7 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.6.10 Synchronous Serial Controller (SSC)
40.6.10.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.6.10.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.6.10.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
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Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly. In the following schematic, TD, TK
and NRST are SAM7S signals, TXD is the delayed data to connect to the device.
40.6.11 Two-wire Interface (TWI)
40.6.11.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191
Problem Fix/Workaround
None.
40.6.11.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.6.11.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.6.11.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
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TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.6.11.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.6.12 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.6.12.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.6.12.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.6.12.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.6.12.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.6.12.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.6.13 Voltage Regulator
40.6.13.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.6.13.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
40.6.14 Watchdog Timer (WDT)
40.6.14.1 WDT: The Watchdog Timer May Lock the Device in a Reset State
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Reset enabled (WDRSTEN
set at 1), the Watchdog Timer may lock the device in a reset state when the user restarts the watchdog
(WDDRSTT). The only way to recover from this state is a power-on reset. The issue depends on the values of
WDD and WDV in the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog Reset enabled (WDRSTEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
40.6.14.2 WDT: The Watchdog Timer Status Register and Interrupt
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Fault Interrupt enabled
(WDFIEN set at 1), the Watchdog Timer may trigger the interrupt (wdt_fault) erroneously. The Watchdog Timer
Status Register may be wrong also (WDERR and WDUNF). The issue depends on the values of WDD and WDV in
the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not us the Watchdog Timer with the Watchdog fault Interrupt enabled (WDFIEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
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40.7 SAM7S256 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Important: Section 40.7.13.1 ”WDT: The Watchdog Timer May Lock the Device in a Reset State”
40.7.1 Chip ID
40.7.1.1 Wrong Chip ID Value
The Chip ID is 0x270D 0940 instead of 0x270B 0940.
Problem Fix/Workaround
None.
40.7.2 Analog-to-Digital Converter (ADC)
40.7.2.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.7.2.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.7.2.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.7.2.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.7.2.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
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40.7.2.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.7.2.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.7.2.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.7.2.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.7.2.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.7.2.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.7.3 Non Volatile Memory Bits (NVM Bits)
40.7.3.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 256 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
40.7.4 Parallel Input/Output Controller (PIO)
40.7.4.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.7.4.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.7.4.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.7.5 Power Management Controller (PMC)
40.7.5.1 PMC: Slow Clock Selected in PMC and a Transition Occurs on PA1
Under certain rare circumstances, when CSS = 00 in PMC_MCKR, and PA1 is set as an input and a transition
occurs on PA1, device malfunction might occur.
Problem Fix/Workaround
Do not transition PA1 as an input when CSS = 00 in PMC_MCKR.
40.7.5.2 PMC: Programming CSS in PMC_MCKR Register
Under certain rare circumstances, reprogramming the CSS value in the PMC_MCKR register (i.e switching the
main clock source) might generate malfunction of the device if the following two actions occur simultaneously.
1. Switching from:
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
And
2. Program code is being executed out of flash, or a transition is occurring on PA1, either as an input or
output.
Note: This issue does not occur when transitioning from slow clock to main clock or from slow clock to PLL clock.
Problem Fix/Workaround
When changing CSS in the PMC_MCKR to switch from
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
Ensure that the processor is executing out of SRAM and ensure no transition occurs on PA1, either as an input or
output, starting from writing to the PMC_MCKR register until MCKRDY = 1.
40.7.6 Pulse Width Modulation Controller (PWM)
40.7.6.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.7.6.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.7.6.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
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None.
40.7.6.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.7.6.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.7.7 Real Time Timer (RTT)
40.7.7.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.7.7.2 RTT: RTT_VR May be Corrupted
Under certain rare circumstances, the Real-time Timer Value (RTT_VR) may be corrupted.
Problem Fix/Workaround
Use RTTINC as an increment for a software counter.
40.7.8 Serial Peripheral Interface (SPI)
40.7.8.1 SPI: Bad tx_ready Behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.7.8.2 SPI: LASTXFER (Last Transfer) Behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.7.8.3 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
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Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.7.8.4 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.7.8.5 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.7.8.6 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.7.8.7 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.7.9 Synchronous Serial Controller (SSC)
40.7.9.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
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None.
40.7.9.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.7.9.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly. In the following schematic, TD, TK
and NRST are SAM7S signals, TXD is the delayed data to connect to the device.
40.7.10 Two-wire Interface (TWI)
40.7.10.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.7.10.2 TWI: Software Reset
when a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new transfer
in READ or WRITE mode.
Problem Fix/Workaround
None.
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40.7.10.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.7.10.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.7.10.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.7.11 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.7.11.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.7.11.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.7.11.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.7.11.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
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Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.7.11.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.7.12 Voltage Regulator
40.7.12.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.7.12.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
40.7.13 Watchdog Timer (WDT)
40.7.13.1 WDT: The Watchdog Timer May Lock the Device in a Reset State
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Reset enabled (WDRSTEN
set at 1), the Watchdog Timer may lock the device in a reset state when the user restarts the watchdog
(WDDRSTT). The only way to recover from this state is a power-on reset. The issue depends on the values of
WDD and WDV in the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog Reset enabled (WDRSTEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
40.7.13.2 WDT: The Watchdog Timer Status Register and Interrupt
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Fault Interrupt enabled
(WDFIEN set at 1), the Watchdog Timer may trigger the interrupt (wdt_fault) erroneously. The Watchdog Timer
Status Register may be wrong also (WDERR and WDUNF). The issue depends on the values of WDD and WDV in
the WDT_MR register.
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Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog fault Interrupt enabled (WDFIEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
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40.8 SAM7S256 Errata - Revision B Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S256 Revision B chip ID is 0x270B 0941.
40.8.1 Analog-to-Digital Converter (ADC)
40.8.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.8.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.8.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.8.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.8.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.8.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.8.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.8.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.8.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.8.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.8.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.8.2 Non Volatile Memory Bits (NVM Bits)
40.8.2.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
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This maximum number of write/erase cycles is not applicable to 256 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
40.8.3 Parallel Input/Output Controller (PIO)
40.8.3.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.8.3.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.8.4 Pulse Width Modulation Controller (PWM)
40.8.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.8.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.8.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Problem Fix/Workaround
None.
40.8.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.8.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.8.5 Real Time Timer (RTT)
40.8.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.8.6 Serial Peripheral Interface (SPI)
40.8.6.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRSTin the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select.
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.8.6.2 SPI: Bad tx_ready Behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.8.6.3 SPI: LASTXFER (Last Transfer) Behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
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40.8.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.8.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.8.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.8.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.8.6.8 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
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40.8.7 Synchronous Serial Controller (SSC)
40.8.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.8.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.8.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly. In the following schematic, TD, TK
and NRST are SAM7S signals, TXD is the delayed data to connect to the device.
40.8.8 Two-wire Interface (TWI)
40.8.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
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40.8.8.2 TWI: Software Reset
when a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new transfer
in READ or WRITE mode.
Problem Fix/Workaround
None.
40.8.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.8.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.8.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.8.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.8.9.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.8.9.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.8.9.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
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None.
40.8.9.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.8.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.8.10 Voltage Regulator
40.8.10.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.8.10.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.9 SAM7S256 Errata - Revision C Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S256 Revision C chip ID is 0x270B 0942.
40.9.1 Embedded Flash Controller (EFC)
40.9.1.1 EFC: Embedded Flash Access Time 1
The embedded Flash maximum access time is 20 MHz (instead of 30 MHz) at zero Wait State (FWS = 0).
The maximum operating frequency with one Wait State (FWS = 1) is 48.1 MHz (instead of 55 MHz). Above 48.1
MHz and up to 55 MHz, two Wait States (FWS = 2) are required.
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.9.2 Parallel Input/Output Controller (PIO)
40.9.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.9.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.9.3 Pulse Width Modulation Controller (PWM)
40.9.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.9.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.9.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.9.4 Real Time Timer (RTT)
40.9.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.9.5 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.9.5.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.10 SAM7S256 Errata - Revision D Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S256 Revision D chip ID is 0x270B0943.
40.10.1 Embedded Flash Controller (EFC)
40.10.1.1 EFC: Embedded Flash Access Time 1
The embedded Flash maximum access time is 20 MHz (instead of 30 MHz) at zero Wait State (FWS = 0).
The maximum operating frequency with one Wait State (FWS = 1) is 48.1 MHz (instead of 55 MHz). Above 48.1
MHz and up to 55 MHz, two Wait States (FWS = 2) are required.
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.10.2 Parallel Input/Output Controller (PIO)
40.10.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.10.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.10.3 Pulse Width Modulation Controller (PWM)
40.10.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.10.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.10.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.10.4 Real Time Timer (RTT)
40.10.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.10.5 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.10.5.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.11 SAM7S128 Errata - Manufacturing Number 58818C
Refer to Section 40.1 “Marking” on page 595.
Important: Section 40.11.14.1 ”WDT: The Watchdog Timer May Lock the Device in a Reset State”
40.11.1 Chip ID
40.11.1.1 Wrong Chip ID Value
The Chip ID is 0x270C0740 instead of 0x270A0740.
Problem Fix/Workaround
None.
40.11.2 Analog-to-Digital Converter (ADC)
40.11.2.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.11.2.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.11.2.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.11.2.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.11.2.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
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40.11.2.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.11.2.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.11.2.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.11.2.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.11.2.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.11.2.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.11.3 Master Clock (MCK)
40.11.3.1 MCK: Limited Master Clock Frequency Ranges
If the Flash is operating without wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with one wait state, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with two wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 25 MHz.
If the Flash is operating with three wait states, the frequency of the Master Clock MCK must be lower than 3 MHz
or higher than 38 MHz.
If these constraints are not respected, the correct operation of the system cannot be guaranteed and either data or
prefetch abort might occur.
The maximum operating frequencies (at 30 MHz @ 0 Wait States and 55 MHz @ 1 Wait State) as stated in
Table 37-24, “Embedded Flash Wait States,” on page 582, are still applicable.
Note: It is not necessary to use 2 o 3 wait states because the Flash can operate at maximum frequency with only 1 wait state.
Problem Fix/Workaround
The user must ensure that the device is running at the authorized frequency by programming the PLL properly to
not run within the forbidden frequency range.
40.11.4 Non Volatile Memory Bits (NVM Bits)
40.11.4.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 128 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
40.11.5 Parallel Input/Output Controller (PIO)
40.11.5.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.11.5.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
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This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.11.5.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.11.6 Power Management Controller (PMC)
40.11.6.1 PMC: Slow Clock Selected in PMC and a Transition Occurs on PA1
Under certain rare circumstances, when CSS = 00 in PMC_MCKR, and PA1 is set as an input and a transition
occurs on PA1, device malfunction might occur.
Problem Fix/Workaround
Do not transition PA1 as an input when CSS = 00 in PMC_MCKR.
40.11.6.2 PMC: Programming CSS in PMC_MCKR Register
Under certain rare circumstances, reprogramming the CSS value in the PMC_MCKR register (i.e switching the
main clock source) might generate malfunction of the device if the following two actions occur simultaneously.
1. Switching from:
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
And
2. Program code is being executed out of flash, or a transition is occurring on PA1, either as an input or
output.
Note: This issue does not occur when transitioning from slow clock to main clock or from slow clock to PLL clock.
Problem Fix/Workaround
When changing CSS in the PMC_MCKR to switch from
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
Ensure that the processor is executing out of SRAM and ensure no transition occurs on PA1, either as an input or
output, starting from writing to the PMC_MCKR register until MCKRDY = 1.
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.11.7 Pulse Width Modulation Controller (PWM)
40.11.7.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.11.7.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.11.7.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.11.7.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.11.7.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.11.8 Real Time Timer (RTT)
40.11.8.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.11.8.2 RTT: RTT_VR May be Corrupted
Under certain rare circumstances, the Real-time Timer Value (RTT_VR) may be corrupted.
Problem Fix/Workaround
Use RTTINC as an increment for a software counter.
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40.11.9 Serial Peripheral Interface (SPI)
40.11.9.1 SPI: Bad tx_ready behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.11.9.2 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.11.9.3 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.11.9.4 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.11.9.5 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.11.9.6 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.11.9.7 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
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This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.11.10 Synchronous Serial Controller (SSC)
40.11.10.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.11.10.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.11.10.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
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40.11.11 Two-wire Interface (TWI)
40.11.11.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.11.11.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.11.11.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.11.11.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
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40.11.11.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.11.12 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.11.12.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.11.12.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.11.12.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.11.12.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.11.12.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.11.13 Voltage Regulator
40.11.13.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
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Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.11.13.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
40.11.14 Watchdog Timer (WDT)
40.11.14.1 WDT: The Watchdog Timer May Lock the Device in a Reset State
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Reset enabled (WDRSTEN
set at 1), the Watchdog Timer may lock the device in a reset state when the user restarts the watchdog
(WDDRSTT). The only way to recover from this state is a power-on reset. The issue depends on the values of
WDD and WDV in the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog Reset enabled (WDRSTEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
40.11.14.2 WDT: The Watchdog Timer Status Register and Interrupt
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Fault Interrupt enabled
(WDFIEN set at 1), the Watchdog Timer may trigger the interrupt (wdt_fault) erroneously. The Watchdog Timer
Status Register may be wrong also (WDERR and WDUNF). The issue depends on the values of WDD and WDV in
the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog fault Interrupt enabled (WDFIEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
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40.12 SAM7S128 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Important: Section 40.12.13.1 ”WDT: The Watchdog Timer May Lock the Device in a Reset State”
40.12.1 Chip ID
40.12.1.1 Wrong Chip ID Value
The Chip ID is 0x270C 0740 instead of 0x270A 0740.
Problem Fix/Workaround
None.
40.12.2 Analog-to-Digital Converter (ADC)
40.12.2.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.12.2.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.12.2.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.12.2.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.12.2.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
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40.12.2.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.12.2.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.12.2.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.12.2.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.12.2.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.12.2.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.12.3 Non Volatile Memory Bits (NVM Bits)
40.12.3.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 128 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
40.12.4 Parallel Input/Output Controller (PIO)
40.12.4.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 5 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.12.4.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.12.4.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.12.5 Power Management Controller (PMC)
40.12.5.1 PMC: Slow Clock Selected in PMC and a Transition Occurs on PA1
Under certain rare circumstances, when CSS = 00 in PMC_MCKR, and PA1 is set as an input and a transition
occurs on PA1, device malfunction might occur.
Problem Fix/Workaround
Do not transition PA1 as an input when CSS = 00 in PMC_MCKR.
40.12.5.2 PMC: Programming CSS in PMC_MCKR Register
Under certain rare circumstances, reprogramming the CSS value in the PMC_MCKR register (i.e switching the
main clock source) might generate malfunction of the device if the following two actions occur simultaneously.
1. Switching from:
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
And
2. Program code is being executed out of flash, or a transition is occurring on PA1, either as an input or
output.
Note: This issue does not occur when transitioning from slow clock to main clock or from slow clock to PLL clock.
Problem Fix/Workaround
When changing CSS in the PMC_MCKR to switch from
– PLL Clock to Slow Clock or
– PLL Clock to Main Clock or
– Main Clock to PLL Clock or
– Main Clock to Slow Clock
Ensure that the processor is executing out of SRAM and ensure no transition occurs on PA1, either as an input or
output, starting from writing to the PMC_MCKR register until MCKRDY = 1.
40.12.6 Pulse Width Modulation Controller (PWM)
40.12.6.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.12.6.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.12.6.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
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None.
40.12.6.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.12.6.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.12.7 Real Time Timer (RTT)
40.12.7.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.12.7.2 RTT: RTT_VR May be Corrupted
Under certain rare circumstances, the Real-time Timer Value (RTT_VR) may be corrupted.
Problem Fix/Workaround
Use RTTINC as an increment for a software counter.
40.12.8 Serial Peripheral Interface (SPI)
40.12.8.1 SPI: Bad tx_ready behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.12.8.2 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.12.8.3 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
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Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.12.8.4 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.12.8.5 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.12.8.6 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.12.8.7 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.12.9 Synchronous Serial Controller (SSC)
40.12.9.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
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40.12.9.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.12.9.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.12.10 Two-wire Interface (TWI)
40.12.10.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.12.10.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
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40.12.10.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.12.10.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.12.10.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.12.11 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.12.11.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.12.11.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.12.11.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.12.11.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
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Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.12.11.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.12.12 Voltage Regulator
40.12.12.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.12.12.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
40.12.13 Watchdog Timer (WDT)
40.12.13.1 WDT: The Watchdog Timer May Lock the Device in a Reset State
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Reset enabled (WDRSTEN
set at 1), the Watchdog Timer may lock the device in a reset state when the user restarts the watchdog
(WDDRSTT). The only way to recover from this state is a power-on reset. The issue depends on the values of
WDD and WDV in the WDT_MR register.
Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog Reset enabled (WDRSTEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
40.12.13.2 WDT: The Watchdog Timer Status Register and Interrupt
Under certain rare circumstances, if the Watchdog Timer is used with the Watchdog Fault Interrupt enabled
(WDFIEN set at 1), the Watchdog Timer may trigger the interrupt (wdt_fault) erroneously. The Watchdog Timer
Status Register may be wrong also (WDERR and WDUNF). The issue depends on the values of WDD and WDV in
the WDT_MR register.
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Problem Fix/Workaround
Two workarounds are possible.
1. Either do not use the Watchdog Timer with the Watchdog fault Interrupt enabled (WDFIEN set at 1),
2. or set WDD to 0xFFF and in addition use only one of the following values for WDV: 0xFFF, 0xDFF, 0xBFF,
0x9FF, 0x7FF, 0x77F, 0x6FF, 0x67F, 0x5FF, 0x57F, 0x4FF, 0x47F, 0x3FF, 0x37F, 0x2FF, 0x27F, 0x1FF,
0x1BF, 0x17F, 0x13F, 0x0FF, 0x0DF, 0x0BF, 0x09F, 0x07F, 0x06F, 0x05F, 0x04F, 0x03F, 0x037, 0x02f,
0x027, 0x01F, 0x01B, 0x017, 0x013 and 0x00F.
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40.13 SAM7S128 Errata - Revision B Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S128 Revision B chip ID is: 0x270A 0741.
40.13.1 Analog-to-Digital Converter (ADC)
40.13.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.13.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.13.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.13.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.13.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.13.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.13.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.13.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.13.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.13.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.13.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.13.2 Non Volatile Memory Bits (NVM Bits)
40.13.2.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
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This maximum number of write/erase cycles is not applicable to 128 KB Flash memory, it remains at 10K for the
Flash memory.
Problem Fix/Workaround
None.
40.13.3 Parallel Input/Output Controller (PIO)
40.13.3.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.13.3.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.13.4 Pulse Width Modulation Controller (PWM)
40.13.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.13.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.13.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Problem Fix/Workaround
None.
40.13.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.13.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.13.5 Real Time Timer (RTT)
40.13.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.13.6 Serial Peripheral Interface (SPI)
40.13.6.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRSTin the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select.
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.13.6.2 SPI: Bad tx_ready behavior when CSAAT = 1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT = 1 and SCBR = 1.
40.13.6.3 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
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Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.13.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.13.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.13.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.13.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.13.6.8 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
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40.13.7 Synchronous Serial Controller (SSC)
40.13.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.13.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.13.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.13.8 Two-wire Interface (TWI)
40.13.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
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40.13.8.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.13.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.13.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.13.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.13.9 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.13.9.1 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.13.9.2 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.13.9.3 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
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None.
40.13.9.4 USART: RXBRK Flag Error in Asynchronous Mode
In receiver mode, when there are two consecutive characters (without timeguard in between), RXBRK is not taken
into account. As a result, the RXBRK flag is not enabled correctly and the frame error flag is set.
Problem Fix/Workaround
Constraints on the transmitter device connected to the SAM7S USART receiver side:
The transmitter may use the timeguard feature or send two STOP conditions. Only one STOP condition is taken
into account by the receiver state machine. After this STOP condition, as there is no valid data, the receiver state
machine will go in idle mode and enable the RXBRK flag.
40.13.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.13.10 Voltage Regulator
40.13.10.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.13.10.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.14 SAM7S128 Errata - Revision C Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S128 Revision C chip ID is 0x270A 0742.
40.14.1 Embedded Flash Controller (EFC)
40.14.1.1 EFC: Embedded Flash Access Time 1
The embedded Flash maximum access time is 20 MHz (instead of 30 MHz) at zero Wait State (FWS = 0).
The maximum operating frequency with one Wait State (FWS = 1) is 48.1 MHz (instead of 55 MHz). Above 48.1
MHz and up to 55 MHz, two Wait States (FWS = 2) are required.
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.14.2 Parallel Input/Output Controller (PIO)
40.14.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.14.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.14.3 Pulse Width Modulation Controller (PWM)
40.14.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.14.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.14.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.14.4 Real Time Timer (RTT)
40.14.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.14.5 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.14.5.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.15 SAM7S128 Errata - Revision D Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S128 Revision C chip ID is 0x270A0743.
40.15.1 Embedded Flash Controller (EFC)
40.15.1.1 EFC: Embedded Flash Access Time 1
The embedded Flash maximum access time is 20 MHz (instead of 30 MHz) at zero Wait State (FWS = 0).
The maximum operating frequency with one Wait State (FWS = 1) is 48.1 MHz (instead of 55 MHz). Above 48.1
MHz and up to 55 MHz, two Wait States (FWS = 2) are required.
Problem Fix/Workaround
Set the number of Wait States (FWS) according to the frequency requirements described in this errata.
40.15.2 Parallel Input/Output Controller (PIO)
40.15.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.15.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.15.3 Pulse Width Modulation Controller (PWM)
40.15.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.15.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.15.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.15.4 Real Time Timer (RTT)
40.15.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.15.5 USART: Universal Synchronous Asynchronous Receiver Transmitter
40.15.5.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.16 SAM7S64 Errata - Manufacturing Number 58814G
Refer to Section 40.1 “Marking” on page 595.
40.16.1 Analog-to-Digital Converter (ADC)
40.16.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.16.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.16.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.16.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.16.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.16.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
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• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.16.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.16.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.16.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.16.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.16.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.16.2 JTAG
40.16.2.1 JTAG: Recommendation for TDI Pin
TDI pin shows a weakness which does not effect the operation of the device. If this pin is driven over 2.0V or
exposed to high electrostatic voltages, the pad might be partially destroyed and this can lead to additional continu-
ous leakage on VDDCORE between 100 and 500 µA.
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However, this does not prevent JTAG operations.
Problem Fix/Workaround
The JTAG port remains operational even if the failure on TDI has happened. Therefore the users can develop their
applications in normal conditions, except the overall system power consumption might be higher. It is recom-
mended to handle the devices carefully during PCB soldering and to correctly ground the manufacturing
equipment.
To prevent any failure on the final customer's systems, it is also recommended to tie the TDI pin at GND in the sys-
tem production release and to not pull it up, as it is shown on the SAM7S-EK Evaluation Board schematics.
40.16.3 Master Clock (MCK)
40.16.3.1 MCK: Limited Master Clock Frequency Ranges
If the Flash is operating without wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with one wait state, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with two wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 25 MHz.
If the Flash is operating with three wait states, the frequency of the Master Clock MCK must be lower than 3 MHz
or higher than 38 MHz.
If these constraints are not respected, the correct operation of the system cannot be guaranteed and either data or
prefetch abort might occur.
The maximum operating frequencies (at 30 MHz @ 0 Wait States and 55 MHz @ 1 Wait State) as stated in
Table 37-24, “Embedded Flash Wait States,” on page 582, are still applicable.
Note: It is not necessary to use 2 o 3 wait states because the Flash can operate at maximum frequency with only 1 wait state.
Problem Fix/Workaround
The user must ensure that the device is running at the authorized frequency by programming the PLL properly to
not run within the forbidden frequency range.
40.16.4 Non Volatile Memory Bits (NVM Bits)
40.16.4.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 64 KB Flash memory, it remains at10K for the
Flash memory.
Problem Fix/Workaround
None.
40.16.5 Parallel Input/Output Controller (PIO)
40.16.5.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
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Set the I/O to VDDIO by internal or external pull-up.
40.16.5.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.16.5.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.16.6 Pulse Width Modulation Controller (PWM)
40.16.6.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.16.6.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.16.6.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.16.6.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.16.6.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.16.7 Real Time Timer (RTT)
40.16.7.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.16.8 Serial Peripheral Interface (SPI)
40.16.8.1 20. SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
Problem Fix/Workaround
None.
40.16.8.2 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.16.8.3 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.16.8.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
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40.16.8.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.16.8.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.16.8.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.16.8.8 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
None.
40.16.8.9 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.16.8.10 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.16.8.11 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
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• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.16.9 Synchronous Serial Controller (SSC)
40.16.9.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.16.9.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.16.9.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
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40.16.10 Two-wire Interface (TWI)
40.16.10.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.16.10.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.16.10.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.16.10.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
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40.16.10.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.16.11 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.16.11.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.16.11.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.16.11.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.16.11.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.16.11.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.16.12 Voltage Regulator
40.16.12.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
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None.
40.16.12.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.17 SAM7S64 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S64 Revision A chip ID is 0x2709 0540.
40.17.1 Analog-to-Digital Converter (ADC)
40.17.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.17.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.17.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.17.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.17.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.17.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.17.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.17.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.17.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.17.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.17.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.17.2 Non Volatile Memory Bits (NVM Bits)
40.17.2.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 64 KB Flash memory, it remains at10K for the
Flash memory.
Problem Fix/Workaround
None.
40.17.3 Parallel Input/Output Controller (PIO)
40.17.3.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.17.3.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.17.3.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.17.4 Pulse Width Modulation Controller (PWM)
40.17.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.17.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.17.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.17.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.17.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.17.5 Real Time Timer (RTT)
40.17.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.17.6 Serial Peripheral Interface (SPI)
40.17.6.1 20. SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
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Problem Fix/Workaround
None.
40.17.6.2 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.17.6.3 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.17.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.17.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.17.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.17.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
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40.17.6.8 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
None.
40.17.6.9 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.17.6.10 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.17.6.11 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.17.7 Synchronous Serial Controller (SSC)
40.17.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.17.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
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40.17.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.17.8 Two-wire Interface (TWI)
40.17.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.17.8.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.17.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
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40.17.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.17.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.17.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.17.9.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.17.9.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.17.9.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.17.9.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.17.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.17.10 Voltage Regulator
40.17.10.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.17.10.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.18 SAM7S64 Errata - Revision B Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S64 Revision B chip ID is: 0x2709 0543.
40.18.1 Analog-to-Digital Converter (ADC)
40.18.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.18.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.18.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.18.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.18.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.18.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.18.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.18.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.18.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.18.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.18.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.18.2 Non Volatile Memory Bits (NVM Bits)
40.18.2.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 64 KB Flash memory, it remains at10K for the
Flash memory.
Problem Fix/Workaround
None.
40.18.3 Parallel Input/Output Controller (PIO)
40.18.3.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.18.3.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.18.4 Pulse Width Modulation Controller (PWM)
40.18.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.18.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Problem Fix/Workaround
Do not write 0 in the period register.
40.18.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.18.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.18.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.18.5 Real Time Timer (RTT)
40.18.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.18.6 Serial Peripheral Interface (SPI)
40.18.6.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRSTin the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select.
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.18.6.2 SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
Problem Fix/Workaround
None.
701
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.18.6.3 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.18.6.4 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.18.6.5 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.18.6.6 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.18.6.7 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.18.6.8 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.18.6.9 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
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SAM7S Series [DATASHEET]
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None.
40.18.6.10 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.18.6.11 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.18.6.12 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.18.7 Synchronous Serial Controller (SSC)
40.18.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.18.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.18.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
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SAM7S Series [DATASHEET]
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Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.18.8 Two-wire Interface (TWI)
40.18.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.18.8.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.18.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.18.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
704
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TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.18.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.18.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.18.9.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.18.9.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.18.9.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.18.9.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.18.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.18.10 Voltage Regulator
40.18.10.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
705
SAM7S Series [DATASHEET]
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Problem Fix/Workaround
None.
40.18.10.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
706
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.19 SAM7S64 Errata - Revision C Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S64 Revision C chip ID is 0x27090544
40.19.1 Parallel Input/Output Controller (PIO)
40.19.1.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V, and 25 µA
at 1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.19.1.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.19.2 Pulse Width Modulation Controller (PWM)
40.19.2.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.19.2.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.19.2.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
707
SAM7S Series [DATASHEET]
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None.
40.19.3 Real Time Timer (RTT)
40.19.3.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
708
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.20 SAM7S321 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S321 Revision A chip ID is: 0x2708 0342.
40.20.1 Analog-to-Digital Converter (ADC)
40.20.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.20.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.20.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.20.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.20.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.20.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
709
SAM7S Series [DATASHEET]
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.20.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.20.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.20.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.20.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.20.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
710
SAM7S Series [DATASHEET]
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40.20.2 Parallel Input/Output Controller (PIO)
40.20.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.20.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.20.3 Pulse Width Modulation Controller (PWM)
40.20.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.20.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.20.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.20.3.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
711
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.20.3.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.20.4 Real Time Timer (RTT)
40.20.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.20.5 Serial Peripheral Interface (SPI)
40.20.5.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRSTin the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select.
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.20.5.2 SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
Problem Fix/Workaround
None.
40.20.5.3 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.20.5.4 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
712
SAM7S Series [DATASHEET]
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Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.20.5.5 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.20.5.6 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.20.5.7 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.20.5.8 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.20.5.9 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
713
SAM7S Series [DATASHEET]
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40.20.6 Synchronous Serial Controller (SSC)
40.20.6.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.20.6.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.20.6.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.20.7 Two-wire Interface (TWI)
40.20.7.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.20.7.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
714
SAM7S Series [DATASHEET]
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Problem Fix/Workaround
None.
40.20.7.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.20.7.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.20.7.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.20.8 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.20.8.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.20.8.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.20.8.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
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40.20.8.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.20.8.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.21 SAM7S32 Errata - Manufacturing Number 58814G
Refer to Section 40.1 “Marking” on page 595.
40.21.1 Analog-to-Digital Converter (ADC)
40.21.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.21.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.21.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.21.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.21.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.21.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
• GOVRE inactive,
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• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.21.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.21.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.21.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.21.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.21.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.21.2 JTAG
40.21.2.1 JTAG: Recommendation for TDI Pin
TDI pin shows a weakness which does not effect the operation of the device. If this pin is driven over 2.0V or
exposed to high electrostatic voltages, the pad might be partially destroyed and this can lead to additional continu-
ous leakage on VDDCORE between 100 and 500 µA.
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However, this does not prevent JTAG operations.
Problem Fix/Workaround
The JTAG port remains operational even if the failure on TDI has happened. Therefore the users can develop their
applications in normal conditions, except the overall system power consumption might be higher. It is recom-
mended to handle the devices carefully during PCB soldering and to correctly ground the manufacturing
equipment.
To prevent any failure on the final customer's systems, it is also recommended to tie the TDI pin at GND in the sys-
tem production release and to not pull it up, as it is shown on the SAM7S-EK Evaluation Board schematics.
40.21.3 Master Clock (MCK)
40.21.3.1 MCK: Limited Master Clock Frequency Ranges
If the Flash is operating without wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with one wait state, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 19 MHz.
If the Flash is operating with two wait states, the frequency of the Master Clock MCK must be lower than 3 MHz or
higher than 25 MHz.
If the Flash is operating with three wait states, the frequency of the Master Clock MCK must be lower than 3 MHz
or higher than 38 MHz.
If these constraints are not respected, the correct operation of the system cannot be guaranteed and either data or
prefetch abort might occur.
The maximum operating frequencies (at 30 MHz @ 0 Wait States and 55 MHz @ 1 Wait State) as stated in
Table 37-24, “Embedded Flash Wait States,” on page 582, are still applicable.
Note: It is not necessary to use 2 o 3 wait states because the Flash can operate at maximum frequency with only 1 wait state.
Problem Fix/Workaround
The user must ensure that the device is running at the authorized frequency by programming the PLL properly to
not run within the forbidden frequency range.
40.21.4 Non Volatile Memory Bits (NVM Bits)
40.21.4.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 32 KB Flash memory, it remains at10K for the
Flash memory.
Problem Fix/Workaround
None.
40.21.5 Parallel Input/Output Controller (PIO)
40.21.5.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
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Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.21.5.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.21.5.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.21.6 Pulse Width Modulation Controller (PWM)
40.21.6.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.21.6.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.21.6.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.21.6.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.21.6.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.21.7 Serial Peripheral Interface (SPI)
40.21.7.1 SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
Problem Fix/Workaround
None.
40.21.7.2 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.21.7.3 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.21.7.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.21.7.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
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selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.21.7.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.21.7.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.21.7.8 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
None.
40.21.7.9 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.21.7.10 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.21.7.11 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
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• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.21.8 Synchronous Serial Controller (SSC)
40.21.8.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.21.8.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.21.8.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
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40.21.9 Two-wire Interface (TWI)
40.21.9.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.21.9.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.21.9.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.21.9.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.21.9.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.21.10 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.21.10.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.21.10.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
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CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.21.10.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.21.10.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.21.10.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
40.21.11 Voltage Regulator
40.21.11.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.21.11.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.22 SAM7S32 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S32 Revision A chip ID is 0x2708 0340.
40.22.1 Analog-to-Digital Converter (ADC)
40.22.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.22.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.22.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.22.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.22.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.22.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.22.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.22.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.22.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.22.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.22.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.22.2 Non Volatile Memory Bits (NVM Bits)
40.22.2.1 NVM Bits: Write/Erase Cycles Number
The maximum number of write/erase cycles for Non Volatile Memory bits is 100. This includes Lock Bits (LOCKx),
General Purpose NVM bits (GPNVMx) and the Security Bit.
This maximum number of write/erase cycles is not applicable to 64 KB Flash memory, it remains at10K for the
Flash memory.
Problem Fix/Workaround
None.
40.22.3 Parallel Input/Output Controller (PIO)
40.22.3.1 PIO: Leakage on PA17 - PA20
When PA17, PA18, PA19 or PA20 (the I/O lines multiplexed with the analog inputs) are set as digital inputs with
pull-up disabled, the leakage can be 9 µA in worst case and 90 nA in typical case per I/O when the I/O is set exter-
nally at low level.
Problem Fix/Workaround
Set the I/O to VDDIO by internal or external pull-up.
40.22.3.2 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.22.3.3 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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40.22.4 Pulse Width Modulation Controller (PWM)
40.22.4.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.22.4.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.22.4.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.22.4.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.22.4.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.22.5 Real Time Timer (RTT)
40.22.5.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.22.6 Serial Peripheral Interface (SPI)
40.22.6.1 20. SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
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Problem Fix/Workaround
None.
40.22.6.2 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.22.6.3 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.22.6.4 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.22.6.5 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.22.6.6 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.22.6.7 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
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40.22.6.8 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
None.
40.22.6.9 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.22.6.10 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.22.6.11 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.22.7 Synchronous Serial Controller (SSC)
40.22.7.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.22.7.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
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40.22.7.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
40.22.8 Two-wire Interface (TWI)
40.22.8.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.22.8.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.22.8.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
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40.22.8.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
40.22.8.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.22.9 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.22.9.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.22.9.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.22.9.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.22.9.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.22.9.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
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40.22.10 Voltage Regulator
40.22.10.1 Voltage Regulator: Current Consumption in Deep Mode
Current consumption in Deep Mode is maximum 60 µA instead of 25 µA.
Due to current rejection from VDDIN to VDDCORE, the current consumption in Deep Mode cannot be guaranteed.
Instead, 60 µA is guaranteed whatever the condition.
Problem Fix/Workaround
None.
40.22.10.2 Voltage Regulator: Load Versus Temperature
Maximum load is 50 mA at 85 °C (instead of 100 mA).
Maximum load is 100 mA at 70°C.
Problem Fix/Workaround
None.
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40.23 SAM7S32 Errata - Revision B Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S32 Revision B chip ID is 0x2708 0341.
40.23.1 Analog-to-Digital Converter (ADC)
40.23.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.23.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.23.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.23.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.23.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.23.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
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• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.23.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.23.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.23.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.23.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.23.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
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40.23.2 Parallel Input/Output Controller (PIO)
40.23.2.1 PIO: Electrical Characteristics on NRST and PA0-PA16 and PA21-31
When NRST or PA0-PA16 or PA21-PA31 are set as digital inputs with pull-up enabled, the voltage of the I/O stabi-
lizes at VPull-up.
This condition causes a leakage through VDDIO. This leakage is 45 µA per pad in worst case at 3.3 V and 25 µA at
1.8V.
Problem Fix/Workaround
It is recommended to use an external pull-up if needed.
40.23.2.2 PIO: Drive Low NRST, PA0-PA16 and PA21-PA31
When NRST or PA0-PA16 and or PA21-PA31 are set as digital inputs with pull-up enabled, driving the I/O with an
output impedance higher than 500 ohms may not drive the I/O to a logical zero.
Problem Fix/Workaround
Output impedance must be lower than 500 ohms.
40.23.3 Pulse Width Modulation Controller (PWM)
40.23.3.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.23.3.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.23.3.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.23.3.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Vpull-up
VPull-up Min VPull-up Max
VDDIO - 0.65 V VDDIO - 0.45 V
I Leakage
Parameter Typ Max
I Leakage at 3,3V 2.5 µA 45 µA
I Leakage at 1.8V 1 µA 25 µA
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Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.23.3.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.23.4 Real Time Timer (RTT)
40.23.4.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.23.5 Serial Peripheral Interface (SPI)
40.23.5.1 SPI: Software Reset Must be Written Twice
If a software reset (SWRSTin the SPI Control Register) is performed, the SPI may not work properly (the clock is
enabled before the chip select.
Problem Fix/Workaround
The SPI Control Register field, SWRST needs to be written twice to be set correctly.
40.23.5.2 20. SPI: Pulse Generation on SPCK
In Master Mode, there is an additional pulse generated on SPCK when the SPI is configured as follows:
– The Baudrate is odd and different from 1
– The Polarity is set to 1
– The Phase is set to 0
Problem Fix/Workaround
None.
40.23.5.3 SPI: Bad tx_ready behavior when CSAAT=1 and SCBR = 1
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed consecutively on
the same slave with an IDLE state between them, the tx_ready signal does not rise after the second data has been
transferred in the shifter. This can imply for example, that the second data is sent twice.
Problem Fix/Workaround
Do not use the combination CSAAT=1 and SCBR =1.
40.23.5.4 SPI: LASTXFER (Last Transfer) behavior
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on the data written in
the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes a “1” in the bit 24 (LASTXFER bit) of
the SPI_TDR, the chip select will rise as soon as the TXEMPTY flag is set.
Problem Fix/Workaround
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Use the CS in PIO mode when PDC mode is required and CS has to be maintained between transfers.
40.23.5.5 SPI: SPCK Behavior in Master Mode
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx registers.
40.23.5.6 SPI: Chip Select and Fixed Mode
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip select 0, the output
spi_size sampled by the PDC will depend on the field, BITS (Bits per Transfer) of SPI_CSR0 register, whatever the
selected Chip select is. For example, if SPI_CSR0 is configured for a 10-bit transfer whereas SPI_CSR1 is config-
ured for an 8-bit transfer, when a transfer is performed in Fixed mode through the PDC, on Chip select 1, the
transfer will be considered as a HalfWord transfer.
Problem Fix/Workaround
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the BITS field of the
SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of the CSRy Register.
40.23.5.7 SPI: Baudrate Set to 1
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency) and when the BITS
field of the SPI_CSR register (number of bits to be transmitted) equals an ODD value (in this case 9,11,13 or 15),
an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
Problem Fix/Workaround
None.
40.23.5.8 SPI: Disable In Slave Mode
The SPI disable is not possible in slave mode.
Problem Fix/Workaround
Read first the received data, then perform the software reset.
40.23.5.9 SPI: Disable Issue
The SPI Command “SPI Disable” is not possible during a transfer, it must be performed only after TX_EMPTY ris-
ing else there is everlasting dummy transfers occur.
Problem Fix/Workaround
None.
40.23.5.10 SPI: Software Reset and SPIEN Bit
The SPI Command “software reset” does not reset the SPIEN config bit. Therefore rewriting an SPI enable com-
mand does not set TX_READY, TX_EMPTY flags.
Problem Fix/Workaround
Send SPI disable command after a software reset.
40.23.5.11 SPI: CSAAT = 1 and Delay
If CSAAT = 1 for current access and there is no more TX request for a time greater than DLYBCT + DLYBCS, then
if an access is requested on another slave, the NPCS bus switches from one CS to the one requested without
DLYBCS. External Slaves may reach a contention on SPI_MISO line for a short period.
Problem Fix/Workaround
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Assert the Last Transfer Command (NPCS de-activation) for the last character of each slave.
40.23.5.12 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.23.6 Synchronous Serial Controller (SSC)
40.23.6.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.23.6.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.23.6.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
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40.23.7 Two-wire Interface (TWI)
40.23.7.1 TWI: Clock Divider
The value of CLDIV x 2CKDIV must be less than or equal to 8191, the value of CHDIV x 2CKDIV must be less than or
equal to 8191⋅
Problem Fix/Workaround
None.
40.23.7.2 TWI: Software Reset
When a software reset is performed during a frame and when TWCK is low, it is impossible to initiate a new trans-
fer in READ or WRITE mode.
Problem Fix/Workaround
None.
40.23.7.3 TWI: Disabling Does not Operate Correctly
Any transfer in progress is immediately frozen if the Control Register (TWI_CR) is written with the bit MSDIS at 1.
Furthermore, the status bits TXCOMP and TXRDY in the Status Register (TWI_SR) are not reset.
Problem Fix/Workaround
The user must wait for the end of transfer before disabling the TWI. In addition, the interrupts must be disabled
before disabling the TWI.
40.23.7.4 TWI: NACK Status Bit Lost
During a master frame, if TWI_SR is read between the Non Acknowledge condition detection and the TXCOMP bit
rising in the TWI_SR, the NACK bit is not set.
Problem Fix/Workaround
The user must wait for the TXCOMP status bit by interrupt and must not read the TWI_SR as long as transmission
is not completed.
TXCOMP and NACK fields are set simultaneously and the NACK field is reset after the read of the TWI_SR.
741
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.23.7.5 TWI: Possible Receive Holding Register Corruption
When loading the TWI_RHR, the transfer direction is ignored. The last data byte received in the TWI_RHR is cor-
rupted at the end of the first subsequent transmit data byte. Neither RXRDY nor OVERRUN status bits are set if
this occurs.
Problem Fix/Workaround
The user must be sure that received data is read before transmitting any new data.
40.23.8 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.23.8.1 USART: Hardware Handshake
The Hardware Handshake does not work at speeds higher than 750 kbauds.
Problem Fix/Workaround
None.
40.23.8.2 USART: CTS in Hardware Handshaking
When Hardware Handshaking is used and if CTS goes low near the end of the starting bit, a character can be lost.
Problem Fix/Workaround
CTS must not go low during a time slot occurring between 2 Master Clock periods before the starting bit and 16
Master Clock periods after the rising edge of the starting bit.
40.23.8.3 USART: Hardware Handshaking – Two Characters Sent
If CTS switches from 0 to 1 during the TX of a character and if the holding register (US_THR) is not empty, the con-
tent of US_THR will also be transmitted.
Problem Fix/Workaround
Don't use the PDC in transmit mode and do not fill US_THR before TXEMPTY is set at 1.
40.23.8.4 USART: XOFF Character Bad Behavior
The XOFF character is sent only when the receive buffer is detected full. While the XOFF is being sent, the remote
transmitter is still transmitting. As only one Holding register is available in the receiver, characters will be lost in
reception. This makes the software handshaking functionality ineffective.
Problem Fix/Workaround
None.
40.23.8.5 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
742
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.24 SAM7S161 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S161 Revision A chip ID is 0x2705 0241.
40.24.1 Analog-to-Digital Converter (ADC)
40.24.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.24.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.24.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.24.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.24.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.24.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
743
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.24.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.24.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.24.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.24.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.24.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.24.2 Pulse Width Modulation Controller (PWM)
40.24.2.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
744
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.24.2.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.24.2.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.24.2.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.24.2.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.24.3 Real Time Timer (RTT)
40.24.3.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.24.4 Serial Peripheral Interface (SPI)
40.24.4.1 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
745
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.24.5 Synchronous Serial Controller (SSC)
40.24.5.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.24.5.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.24.5.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
746
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.24.6 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.24.6.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
747
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.25 SAM7S16 Errata - Revision A Parts
Refer to Section 40.1 “Marking” on page 595.
Note: AT91SAM7S16 Revision A chip ID is 0x2705 0240.
40.25.1 Analog-to-Digital Converter (ADC)
40.25.1.1 ADC: DRDY Bit Cleared
The DRDY Flag should be clear only after a read of ADC_LCDR (Last Converted Data Register). A read of any
ADC_CDRx register (Channel Data Register) automatically clears the DRDY flag.
Problem Fix/Workaround:
None
40.25.1.2 ADC: DRDY not Cleared on Disable
When reading LCDR at the same instant as an end of conversion, with DRDY already active, DRDY is kept active
regardless of the enable status of the current channel. This sets DRDY, whereas new data is not stored.
Problem Fix/Workaround
None
40.25.1.3 ADC: DRDY Possibly Skipped due to CDR Read
Reading CDR for channel “y” at the same instant as an end of conversion on channel “x” with EOC[x] already
active, leads to skipping to set the DRDY flag if channel “x” is enabled.
Problem Fix/Workaround
Use of DRDY functionality with access to CDR registers should be avoided.
40.25.1.4 ADC: Possible Skip on DRDY when Disabling a Channel
DRDY does not rise when disabling channel “y” at the same time as an end of “x” channel conversion, although
data is stored into CDRx and LCDR.
Problem Fix/Workaround
None.
40.25.1.5 ADC: GOVRE Bit is not Updated
Read of the Status Register at the same instant as an end of conversion leads to skipping the update of the
GOVRE (general overrun) flag. GOVRE is neither reset nor set.
For example, if reading the status while an end of conversion is occurring and:
1. GOVRE is active but DRDY is inactive, does not correspond to a new general overrun condition but the
GOVRE flag is not reset.
2. GOVRE is inactive but DRDY is active, does correspond to a new general overrun condition but the
GOVRE flag is not set.
Problem Fix/Workaround
None
40.25.1.6 ADC: GOVRE Bit is not Set when Reading CDR
When reading CDRy (Channel Data Register y) at the same instant as an end of conversion on channel “x” with the
following conditions:
• EOC[x] already active,
• DRDY already active,
748
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
• GOVRE inactive,
• previous data stored in LCDR being neither data from channel “y”, nor data from channel “x”.
GOVRE should be set but is not.
Problem Fix/Workaround
None
40.25.1.7 ADC: GOVRE Bit is not Set when Disabling a Channel
When disabling channel “y” at the same instant as an end of conversion on channel “x”, EOC[x] and DRDY being
already active, GOVRE does not rise.
Note: OVRE[x] rises as expected.
Problem Fix/Workaround
None
40.25.1.8 ADC: OVRE Flag Behavior
When the OVRE flag (on channel i) has been set but the related EOC status (of channel i) has been cleared (by a
read of CDRi or LCDR), reading the Status register at the same instant as an end of conversion (causing the set of
EOC status on channel i), does not lead to a reset of the OVRE flag (on channel i) as expected.
Problem Fix/Workaround:
None
40.25.1.9 ADC: EOC Set although Channel Disabled
If a channel is disabled while a conversion is running and if a read of CDR is performed at the same time as an end
of conversion of any channel occurs, the EOC of the channel with the conversion running may rise (whereas it has
been disabled).
Problem Fix/Workaround
Do not take into account the EOC of a disabled channel
40.25.1.10 ADC: Spurious Clear of EOC Flag
If “x” and “y” are two successively converted channels and “z” is yet another enabled channel (“z” being neither “x”
nor “y”), reading CDR on channel “z” at the same instant as an end of conversion on channel “y” automatically
clears EOC[x] instead of EOC[z].
Problem Fix/Workaround
None.
40.25.1.11 ADC: Sleep Mode
If Sleep mode is activated while there is no activity (no conversion is being performed), it will take effect only after
a conversion occurs.
Problem Fix/Workaround
To activate sleep mode as soon as possible, it is recommended to write successively, ADC Mode Register
(SLEEP) then ADC Control Register (START bit field); to start an analog-to-digital conversion, in order put ADC
into sleep mode at the end of this conversion.
40.25.2 Pulse Width Modulation Controller (PWM)
40.25.2.1 PWM: Update when PWM_CCNTx = 0 or 1
If the Channel Counter Register value is 0 or 1, the Channel Period Register or Channel Duty Cycle Register is
directly modified when writing the Channel Update Register.
749
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Problem Fix/Workaround
Check the Channel Counter Register before writing the update register.
40.25.2.2 PWM: Update when PWM_CPRDx = 0
When Channel Period Register equals 0, the period update is not operational.
Problem Fix/Workaround
Do not write 0 in the period register.
40.25.2.3 PWM: Counter Start Value
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
Problem Fix/Workaround
None.
40.25.2.4 PWM: Constraints on Duty Cycle Value
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Problem Fix/Workaround
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
40.25.2.5 PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Problem Fix/Workaround
Do not disable a channel before completion of one period of the selected clock.
40.25.3 Real Time Timer (RTT)
40.25.3.1 RTT: Possible Event Loss when Reading RTT_SR
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
Problem Fix/Workaround:
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
40.25.4 Serial Peripheral Interface (SPI)
40.25.4.1 SPI: Bad Serial Clock Generation on 2nd Chip Select
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
• Transmitting with the slowest chip select and then with the fastest one, then an additional pulse is generated
on output SPCK during the second transfer.
750
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Problem Fix/Workaround
Do not use a multiple Chip Select configuration where at least one SCRx register is configured with SCBR = 1 and
the others differ from 1 if NCPHA = 0 and CPOL = 1.
If all chip selects are configured with Baudrate = 1, the issue does not appear.
40.25.5 Synchronous Serial Controller (SSC)
40.25.5.1 SSC: Periodic Transmission Limitations in Master Mode
If the Least Significant Bit is sent first (MSBF = 0), the first TAG during the frame synchro is not sent.
Problem Fix/Workaround
None.
40.25.5.2 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as output and TF is programmed as input, it is impossible to emit data when the start of edge
(rising or falling) of synchro has a Start Delay equal to zero.
Problem Fix/Workaround
None.
40.25.5.3 SSC: Transmitter Limitations in Slave Mode
If TK is programmed as an input and TF is programmed as an output and requested to be set to low/high during
data emission, the Frame Synchro signal is generated one bit clock period after the data start and one data bit is
lost. This problem does not exist when generating a periodic synchro.
Problem Fix/Workaround
The data need to be delayed for one bit clock period with an external assembly.
In the following schematic, TD, TK and NRST are SAM7S signals, TXD is the delayed data to connect to the
device.
751
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
40.25.6 Universal Synchronous Asynchronous Receiver Transmitter (USART)
40.25.6.1 USART: DCD is active High instead of Low
The DCD signal is active at High level in the USART Modem Mode.
DCD should be active at Low level.
Problem Fix/Workaround
Add an inverter.
752
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
753
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Revision History
In the tables that follow, the most recent revision appears first.
Version
6175L Comments
Change
Request
Ref
Section 39. ”SAM7S Ordering Information” updated product Ordering Code for SAM7S128 and SAM7S256
MLR rev. D. in Table 39-1, “SAM7S Series Ordering Information” 8380/8467
Section 9.5 ”Debug Unit”, “Chip ID Registers” on page 31, added CHIP ID for SAM7S128 Rev D and
SAM7S256 Rev D.
Table 12-2, “SAM7S Series Debug Unit Chip ID” Added SAM7S128 Rev D and SAM7S256 Rev D;
8380/8467
Errata:
40-1 “Errata Summary Table”: Added SAM7S128D/SAM7S256D Column
Section 40.15 ”SAM7S128 Errata - Revision D Parts”: Added to Errata.
Section 40.10 ”SAM7S256 Errata - Revision D Parts”: Added to Errata.
8381
PWM:
Section 34.4.2 ”Power Management”, removed sentence, “Configuring the PWM does not require the PWM
clock to be enabled.”
8105
WDT:
Section 16.4.2 ”Watchdog Timer Mode Register” added, “Note:The WDD and WDV values must not be
modified within a period of time of 3 slow clock periods following a restart of the watchdog performed by
means of a write access in the WDT_CR register, else the watchdog may trigger an end of period earlier than
expected.”
Section 16.3 ”Functional Description”, after third paragraph; added, “If the watchdog is restarted by writing into
WDT_CR register, the WDT_MR register must not be programmed during a period of time of 3 slow clock
period following the WDT_CR write access. In any case, programming a new value in WDT_MR automatically
initiates a restart instruction.”
8128
Version
6175L Comments
Change
Request
Ref
Product Series Naming Convention
Except for part ordering and library references, AT91 prefix dropped from most nomenclature.
AT91SAM7S becomes SAM7S.
rfo
Debug Unit:
“Chip ID Registers” on page 31, CHIP ID is 0x270B0A4F for AT91SAM7S512 Rev B
Debug and Test Features:
Table 12-2, “SAM7S Series Debug Unit Chip ID”, added AT91SAM7S512 Rev B, Chip ID: 02x270B0A4F.
7945
Errata:
Section 40.5 ”SAM7S512 Errata - Revision B Parts”, Updated AT91SAM7S512 Rev B, Chip ID is
02x270B0A4F.
40-1 “Errata Summary Table”, affixed missing S in three SAM7S256/128 column headers.
7945
7567
754
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175K Comments
Change
Request
Ref
Debug and Test Features:
Table 12-2, “SAM7S Series Debug Unit Chip ID” updated. 7044
ERRATA:
2 columns added to Table 40-1, “Errata Summary Table”: SAM7256/128 Rev C and SAM7S64 Rev C.
Corresponding sections added.
Section 40.5 ”SAM7S512 Errata - Revision B Parts” added. Table 40-1, “Errata Summary Table” updated
too.
7185
Ordering Information:
MRL C column added to Table 39-1, “SAM7S Series Ordering Information”.7185
Version
6175J Comments
Change
Request
Ref
Overview:
Section 6.2 ”Test Pin”, added to SAM-BA Boot recovery procedure, a power cycle of the board is mandatory.
Section 8.10 ”SAM-BA Boot Assistant”, added to SAM-BA Boot recovery procedure, a power cycle of the
board is mandatory.
6068
Section 19.2.4.4 ”General-purpose NVM Bits”, Clear General-purpose Bit command updated (last paragraph
in the section).
6235/5522
EFCS:
Section 19.2.4.1 ”Flash Programming”, constraint on partial programming mode added under Figure 19-6
”Example of Partial Page Programming”
6825
USART:
Section 31.7.9 ”USART Baud Rate Generator Register” 6302
ERRATA:
Section 40.4 ”SAM7S512 Errata - Revision A Parts”
Section 40.4.2.1 ”EFC: Embedded Flash Access Time 1”, updated.
6873
Section 40.4.9.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.6.12.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.7.11.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.8.9.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.11.12.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.12.11.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
Section 40.13.9.4 ”USART: RXBRK Flag Error in Asynchronous Mode”, updated.
6627
755
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175I Comments
Change
Request
Ref
Overview:
Section ”Features”, “Debug Unit (DBGU)” updated with “Mode for General Purpose 2-wire UART Serial
Communication”
Section 7.4 ”Peripheral DMA Controller”, added list of PDC priorities.
Section 9. ”System Controller”, Figure 9-1 and Figure 9-2 RTT is reset by “power_on_reset”.
Section 9.1.1 ”Brownout Detector and Power-on Reset”, fourth paragraph reduced.
Section 12.5.5 ”ID Code Register”, added “The JTAG ID is used in the IEEE 1149.1 JTAG Boundary Scan.”
Section 9.5 ”Debug Unit”, the list; “Chip ID Registers” , chip IDs updated, added SAM7S32 Rev B and SAM7S64
Rev B to the list.
5846
5913
5224
5685
5482
rfo
ADC:
Figure 36-1 ”Analog-to-Digital Converter Block Diagram” VDDANA replaced by VDDIN. PMC added to figure
Section 36.6.2 ”ADC Mode Register”, updated the formula on bit description: “SHTIM: Sample & Hold Time” .
Section 36.5.5 ”Conversion Triggers”, update to the third paragraph detailing hardware trigger.
rfo/5855
5254
5782
PMC:
“PMC Interrupt Enable Register” , “PMC Interrupt Disable Register” , “PMC Status Register” , “PMC Interrupt
Mask Register” , LOCKU and UOSCS removed from bit fields in register tables.
5383
Section 25.7 ”Programming Sequence”, Step6 “Enabling Peripheral Clocks”, AT91SAM7S512 grouped with
devices having 12 peripheral clocks 5398/5798
Section 25.9.10 ”PMC Master Clock Register”, MDIV removed from bit fields in register table. 5438
Section 25.9 ”Power Management Controller (PMC) User Interface”, added PMC_PCK2 to Register Mapping. 5483
RSTC;
Section 13.3.4.4 ”Software Reset”; updated list with details on PERRST and PROCRST. 5436
Electrical Characteristics:
Table 37-2, “DC Characteristics”, CMOS conditions added to IO for VOL and VOH.
Table 37-4, “Brownout Detector Characteristics”, VBOT conditions = Falling edge.
Table 37-19, “External Voltage Reference Input”, added ADVREF Input w/conditions “8-bit resolution mode”.
Section 37.10.2 ”SSC Characteristics”, added to datasheet.
5913
5684
5913
rfo
Ordering Information:
Table 39-1, “LQFP/QFN Ordering Information”, Updated product ordering information by MRL A and MRL B
versions.
rfo
Section 40. ”Errata”
Section 40.2 ”Errata Summary by Product and Revision or Manufacturing Number”, added to Errata.
Section 40-1 ”Errata Summary Table”, added to Errata.
Chip ID noted on products where no chip ID errata exists.
Section 40.18 ”SAM7S64 Errata - Revision B Parts”, added to Errata.
Section 40.23 ”SAM7S32 Errata - Revision B Parts”, removed errata for NVM and Voltage Regulator.
USART: XOFF Character Bad Behavior, removed from all revisions of the AT91SAM7S series components.
rfo
rfo
5336
756
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
“SAM7S512 Errata - Revision A Parts” added, Section 40.4.6.1 ”SPI: Software Reset Must be Written Twice”
“SAM7S256 Errata - Revision B Parts” added, Section 40.8.6.1 ”SPI: Software Reset Must be Written Twice”
“SAM7S128 Errata - Revision B Parts” added, Section 40.13.6.1 ”SPI: Software Reset Must be Written Twice”
“SAM7S321 Errata - Revision A Parts” added, Section 40.20.5.1 ”SPI: Software Reset Must be Written Twice”
“SAM7S32 Errata - Revision B Parts” added, Section 40.23.5.1 ”SPI: Software Reset Must be Written Twice”
5784
“SAM7S512 Errata - Revision A Parts” added, Section 40.4.2.1 ”EFC: Embedded Flash Access Time 1” 5988
Section 40.8 ”SAM7S256 Errata - Revision B Parts”, chip ID updated.
Section 40.13 ”SAM7S128 Errata - Revision B Parts” chip ID updated.
rfo
Version
6175I Comments (Continued)
Change
Request
Ref
757
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175H Comments
Change
Request
Ref.
Overview:
“Features” on page 1 (and all of datasheet) Added AT91SAM7S16/161 to product family.
See: Table 1-1, “Configuration Summary,” on page 3
Section 8.6 “SAM7S161/16” on page 19.
rfo
Section 9.5 ”Debug Unit” Chip ID updated. 4325
Section 6. ”I/O Lines Considerations”, JTAG Port Pin, Test Pin, Erase Pin, updated. 5063
ADC: Section 36.6.2 ”ADC Mode Register”, STARTUP and PRESCAL bitfields updated (width expanded).
AIC: Section 23.8.15 ”AIC Spurious Interrupt Vector Register”, bitfield typo corrected 4749
Debug and Test:
Table 12-2, “SAM7S Series Debug Unit Chip ID,” on page 51, updated.
Table 12.5.5, “ID Code Register,” on page 56, updated.
4325/rfo
EFC: Section 19.3.3 ”MC Flash Status Register” GPNVM2 removed from bit field 10. 4464
FFPI:
Table 20-6, Table 20-7 plus Table 20-8, Table plus Table 20-17, Table 20-18 and Table 20-20 updated
Global update to terms listed below: ≥
Fuse → GPNVM
SFB → SGPB
CFB → CGPB
GFB → GGPB
Section 20.2.5.6 on page 133 &Section 20.3.4.6 on page 141, security bit restraint on access to FFPI explained
4410
3933
4744
PIO:
Section 27.4.5 ”Synchronous Data Output”, typo fixed on PIO_OWSR
PIO User Interface, Table 27-2, “Register Mapping” updates to footnotes, PIO_PSR, PIO_ODSR, PIO_PDSR
3289
3974
PMC: Figure 24-2 ”Typical Crystal Connection” updated 3861
SPI: Section 28.6.4 ”SPI Slave Mode”, Corrected information on OVRES (SPI_SR) and data read in SPI_RDR. 3943
SSC: “SSC Receive Clock Mode Register” on page 426, typo corrected in STTDLY bit field. 4478
TC: Section 33.6 ”Timer Counter (TC) User Interface”, register mapping consolidated in Table 33-4 on page
463 and register offsets indexed. Section 33.6.3 on page 466 to Section 33.6.13 on page 480, register names
updated with indexed offset.
Section 33.6.4 ”TC Channel Mode Register: Capture Mode”, bit field 15 and WAVE bit field description updated.
4583
TWI:
Section 29. ”Two-wire Interface (TWI) SAM7S512/256/128/64/321/32”, section has been updated.
Important changes to this datasheet include a clarification of Atmel TWI compatibility with I2C Standard.
Section 30. ”Two Wire Interface (TWI) SAM7S161/16”, section added specific to the TWI implementation on the
AT91SAM7S16/161 devices.
4247
rfo
PWM:
Section 34.6 ”Pulse Width Modulation Controller (PWM) User Interface”, in the Offset column in Table 34-2,
“Register Mapping”, the PWM channel-dependent registers are indexed. See also, PWM Channel registers
from: Section 34.6.10 on page 497 to Section 34.6.13 on page 499.
4486
758
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
UDP:
Table 35-2, “USB Communication Flow”, Supported Endpoint column updated
In the USB_CSR register, the control endpoints are not effected by the fit field, “EPEDS: Endpoint Enable
Disable” on page 533,
Updated: write1 =....in “RX_DATA_BK0: Receive Data Bank 0” bit field of USB_CSR register.
Updated: write1 =....in “TXPKTRDY: Transmit Packet Ready” bit field of USB_CSR register.
Section 35.6.10 ”UDP Endpoint Control and Status Register” update to code and added instructions regarding
USB clock and system clock cycle, and updated “note” appearing under the code. “wait 3 USB clock cycles and
3 system clock cycles before accessing DPR from RX_DATAx and TXPKTRDY bit
fields, ditto for RX_DATAx and TXPKTRDY bit field descriptions.”
Section 35.2 ”Block Diagram”, in the text below the block diagram, MCK specified as clock used by Master
Clock domain, UDPCK specified as 48 MHz clock used by 12 MHz domain, in peripheral clock requirements.
Section 35.6 ”USB Device Port (UDP) User Interface”, The register mapping table has been updated.
Section 35.6.6 ”UDP Interrupt Mask Register”, bit field 12 has been defined as BIT12 and cannot be masked.
3476
4063
4099
4462
4487
4508
4802
USART:
“USCLKS: Clock Selection” on page 391, bit field in US_MR register, DIV=8 in “Selected Clock” column
Section 31.5.1 ”I/O Lines” 2nd and 3rd paragraphs updated.
“TXEMPTY: TXEMPTY Interrupt Enable” on page 394, no characters when at 1, updated bit field in US_CSR
Section 31.6.2 ”Receiver and Transmitter Control”, In 4th paragraph, “replaced 2nd sentence: The software
resets clear the...”
Section 31.6.5 ”IrDA Mode”, updated with instruction to receive IrDA signals.
Section 31.2 ”Block Diagram”, signal directions from pads to PIO updated in the block diagrams.
Section 31.6.3.1 ”Transmitter Operations”, last (4th) paragraph updated.
3763
3895
3851/4285
4367
4912
4905
rfo
Electrical/Mechanical Characteristics,
Table 37-10, “Main Oscillator Characteristics”, added schematic in footnote to CL and CLEXT symbols.
Table 37-12, “XIN Clock Electrical Characteristics”, updated
Figure 37-2 ”XIN Clock Timing” added below table 36-12
Section 37.2 ”DC Characteristics”and Section 38. ”Mechanical Characteristics”, removed reference to TJ.
ADC Characteristics: Table 37-21, “Transfer Characteristics” INL and DN updated, linked reference to Data
Converter Terminology added below table.
Table 38-5, “LQFP and QFN Package Characteristics” JESD97 Classification updated to be e3.
3867
3965
4656
4006
4969
Table 37-7, “Power Consumption for Different Modes”, updated and expanded ARM core clock information.
Section 37.6 ”Master Clock Characteristics”, moved from former location.
Section 37.7 ”I/O Characteristics”, moved from former location.
rfo
Section 40. ”Errata”, added the following:
Section 40.4 ”SAM7S512 Errata - Revision A Parts” provides list of errata with links.
Section 40.8 ”SAM7S256 Errata - Revision B Parts”
Section 40.13 ”SAM7S128 Errata - Revision B Parts”
Section 40.12 ”AT91SAM7S64 Errata - Revision B Parts”
Section 40.22 ”SAM7S32 Errata - Revision A Parts”
Section 40.23 ”SAM7S32 Errata - Revision B Parts”
rfo
4325
4772
AT91SAM7S16/161:
Section 40.24 ”SAM7S161 Errata - Revision A Parts”
Section 40.25 ”SAM7S16 Errata - Revision A Parts”
rfo
Version
6175H Comments (Continued)
Change
Request
Ref.
759
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
All AT91SAM7S:
“Analog-to-Digital Converter (ADC)” , errata applies to all AT91SAM7S products.
“USART: DCD is active High instead of Low” , errata applies to all AT91SAM7S products.
“SPI: Bad Serial Clock Generation on 2nd Chip Select” , errata applies to all AT91SAM7S products.
“SPI: Bad Behavior when CSAAT = 1 and SCBR = 1”, errata applies to all AT91SAM7S products.
4752
rfo
AT91SAM7S256 Mfg # 58818C, AT91SAM7S256 Parts.A, AT91SAM7S128 Mfg # 58818C,
AT91SAM7S128 Parts A,
added the following:
Section 40.6.14.2 ”WDT: The Watchdog Timer Status Register and Interrupt”
Section 40.7.13.2 ”WDT: The Watchdog Timer Status Register and Interrupt”
Section 40.11.14.2 ”WDT: The Watchdog Timer Status Register and Interrupt”
Section 40.12.13.2 ”WDT: The Watchdog Timer Status Register and Interrupt”
3811
AT91SAM7S512 Section 40.4.9.1 ”USART: CTS in Hardware Handshaking” updated 3954
AT91SAM7S512/256/128, added the following: (and in newly added “B Parts”)
Section 40.4.9.4 ”USART: RXBRK Flag Error in Asynchronous Mode”
Section 40.6.12.4 ”USART: RXBRK Flag Error in Asynchronous Mode”
Section 40.11.12.4 ”USART: RXBRK Flag Error in Asynchronous Mode”
Section 40.12.11.4 ”USART: RXBRK Flag Error in Asynchronous Mode”
4646
Version
6175G Comments
Change
Request
Ref.
Added note to “Description” on page 3 3442
TC: added Figure 32-2 ”Clock Chaining Selection” page 393 3342
SAM-BA Boot: Section 21.5.3 ”USB Device Port”reference to INF example and lit°6123 removed. (Doc
no longer available on web.) 3647
UDP: Table 35-2, “USB Communication Flow”, Isochronous supported endpoint size is 64. 3475
Errata: items added to the Errata Sections listed below.
Section 40.6 ”SAM7S256 Errata - Manufacturing Number 58818C”
Section 40.7 ”SAM7S256 Errata - Revision A Parts”
Section 40.11 ”SAM7S128 Errata - Manufacturing Number 58818C”
Section 40.12 ”SAM7S128 Errata - Revision A Parts”
Watchdog Timer:”The Watchdog Timer May Lock the Device in a Reset State”
Real-time Timer: “RTT_VR May be Corrupted”
Power Management Controller: “Slow Clock Selected in PMC and a Transition Occurs on PA1” and
“Programming CSS in PMC_MCKR Register”
3652
Version
6175H Comments (Continued)
Change
Request
Ref.
760
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175F Comments
Change
Request
Ref.
“Features” on page 1 (global) QFN packages changed to 64- and 48-pad QFN
Manchester Encoder/Decoder removed from USART.
“Features” on page 1, Table 1-1, “Configuration Summary,” on page 3, Section 4. ”Package and
Pinout”Section 39. ”SAM7S Ordering Information”and global, AT91SAM7S512 added to product family.
Section 4.1 ”64-lead LQFP and 64-pad QFN Package Outlines” and Section 4.3 ”48-lead LQFP and 48-
pad QFN Package Outlines”added (replace Mechanical Overview).
Figure 8-1 on page 20 Peripheral and System Controller Memory Mapping has been condensed.
Section 20. ”Embedded Flash Controller (EFC)” EFC0 and EFC1 on AT91SAM7S512 explained.
#2748
Section 10.1 ”User Interface”User Peripherals are mapped between 0xF000 0000 and 0xFFFF EFFF.
Table 10-1 and Table 10-2 SYSIRQ changed to SYSC in “Peripheral Identifiers” rfo review
ADC Block diagram Figure 35-1 on page 479 - dedicated and I/O analog inputs differentiated
”ADC Timings” page 485 WARNING”...See the section ADC Characteristics....” typo fixed.
#3052
#2830
Section 21. ”Fast Flash Programming Interface (FFPI)”, AT91SAM7S512 instructions added to Section
21.2.5.6, and Section 21.2.5.7 on page 155, Section 21.3.4.6 and Section 21.3.4.7 on page 162.
Table 21-1 on page 147 PMD and PGMNVALID bus size for AT91SAM7S32 is [7:0].
#2284
#2748
AIC, Section 24.7.3.1 ”Priority Controller” SRCTYPTE field is in AIC_SMR register, not AIC_SVR
“Advanced Interrupt Controller (AIC) User Interface” , Table 24-2 on page 198 note 2 ref to PID bit fields
#2512
#2548
AT91SAM7 Boot Program Section 22.5 ”SAM-BA Boot” SAM-BA boot principle changed Section 22.2
”Flow Diagram”replaced Figure 22-1 and Figure 22-2 on page 165 #3050
DBGU: ”ARCH: Architecture Identifier” page 259: updated
Functional Block Diagram in Figure 27-1 on page 238 and Section 27.5.12 ”Debug Unit Force NTRST
Register”ice_nreset signal replaced with pad name, Power-on Reset (power_on_reset.)
#2832
“Peripheral DMA Controller (PDC)” User interface description updated page 173. Correct typo to
“ENDTX” bit field name in Section 23.3.3 ”Transfer Counters” 05-460
PIO, Section 15.4.4 ”Output Control” typo corrected
Section 15.4.1 ”Pull-up Resistor Control”, ref to resistor value removed.
Figure 15-3 ”I/O Line Control Logic” page 82, 0 and 1 inverted in the MUX controlled by PIO_MDSR.
05-346
05-497
#3053
”PMC Master Clock Register” on page 231 Corrected name of bitfield “PRES”
Note defining PIDx added to “PMC Peripheral Clock Enable Register” , ”PMC Peripheral Clock Disable
Register” page 226 and
Table 26-2 on page 222: footnotes reassigned.
#1603
#2468
#2748
PWM, updated waveform generation Section 33.5.3.3 ”Changing the Duty Cycle or the Period” page 430. #1677
RSTC; added info on startup counter on crystal oscillator Section 13.3.1 ”Reset Controller Overview” #3005
RTT, added note to ”Functional Description” page 73 #2522
SPI, Figure 28-9 ”Slave Mode Functional Block Diagram” page 272, FLOAD removed
Section 28.6.3 ”Master Mode Operations” change to SPI_RDR information
Section 28.7.1 ”SPI Control Register” added information to bit description ”SWRST: SPI Software Reset”
page 14.
Section 28.7.9 ”SPI Chip Select Register” corrected equation in ”DLYBCT: Delay Between Consecutive
Transfers” page 25.
Section 28.6.3.8 ”Mode Fault Detection” updated
#1542
#1543
#1676
SSC, Section 31.6.6.1 ”Compare Functions” updated IP update
761
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
TC, Table 32-1, “Timer Counter Clock Assignment,” on page 389 has been added.
Section 32.5.4 ”External Event/Trigger Conditions” TIOB defined as external event signal..... updated
”EEVT: External Event Selection” page 412, TIOB chosen as external event signal..... updated in footnote
#2470
#2704
TWI, ”Two-wire Interface (TWI) User Interface” page 294, UNRE and OVRE bit fields removed from TWI
Status and Interrupt register tables. #2470
UDP, Figure 34-2 on page 446 updated,
Section 34.4.1 ”USB Device Transceiver” and Section 34.4.2 ”VBUS Monitoring” page 446 added.
Section 34.5.1.2 ”USB Bus Transactions” updated
Section 34.5.1.3 ”USB Transfer Event Definitions” updated with endpoint information.
Section 34.5.2.2 ”Data IN Transaction” Endpoint use updated.
Section 34.5.2 ”Handling Transactions with USB V2.0 Device Peripheral” page 450, Section reworked,
warnings added.
Section 34.5.3 ”Controlling Device States” page 458, Section reworked and Section 34.5.3.1 ”Not
Powered State” and Section 34.5.3.2 ”Entering Attached State” page 459 added.
Section 34.6 ”USB Device Port (UDP) User Interface”
Section 34.6.2 ”UDP Global State Register” page 464,updated.
Section 34.6.10 ”UDP Endpoint Control and Status Register” page 473, updated
Corrections, improvements, additions and deletions throughout section, new source document.
Section Section 34.5.3.8 ”Sending a Device Remote Wakeup” replaces title: “Sending an External
Resume”.
WAKEUP bit shown in interrupt registers:Section 34.6.4 on page 466 thru Section 34.6.8 on page 471.
RMWUPE, RSMINPR, ESR bits removed from Section 34.6.2 ”UDP Global State Register”.
NOTE: pertinent to USB pullup effect on USB Reset added to Section 34.6.12 ”UDP Transceiver Control
Register”.
source file
update
3288
USART, Section 30.6.7 ”AT91SAM7S512/256/128/64/321 Modem Mode”change to: The control of DTR
output.... RTS output pin.....
Section 30.6.4.1 ”ISO7816 Mode Overview”PAR bit usage
Section 30.6.3 ”Synchronous and Asynchronous Modes” Manchester Encoder/Decoder feature removed
Section 30.5.1 ”I/O Lines”TXD line information added
Section 30.6.1.3 ”AT91SAM7S512/256/128 Fractional Baud Rate in Asynchronous Mode”USART
“functional mode” changed to “normal mode”
Table 30-3 and Table 30-4 on page 312 Di and Fi references corrected in titles.
Figure 30-27 ”IrDA Demodulator Operations” page 328, Figure modified.
Table 30-2, “Baud Rate Example (OVER = 0)last two lines of table removed.
Section 30.6.3.2 ”Asynchronous Receiver” change to second sentence in fourth paragraph, “For the
synchronization mechanism.....”
Section 30.6.3.8 ”Receiver Time-out” list of user options rewritten.
Section 30.7.1 ”USART Control Register” STTTO bit function related to TIMEOUT in US_CSR register.
Section 30.7.6 ”USART Channel Status Register” TIMEOUT bit function related to STTTO in US_CR
register.
#1770
#1552
#2748
#2794 &
rfo review
#2942
#3023
WDT, WV changed to WDV in Section 17.2 ”Block Diagram” and in Section 17.3 ”Functional Description”
and 6th and 7th paragraph rewritten on page 112 beginning with “To prevent a software deadlock....” #3002
Version
6175F Comments (Continued)
Change
Request
Ref.
762
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Section 37. ”SAM7S Electrical Characteristics” AT91SAM7S512 specific info added and changes to the
following tables.
Table 37-2, “DC Characteristics”
Table 37-5, “DC Flash Characteristics SAM7S64/321/32/161/16”
Table 37-6, “DC Flash Characteristics SAM7S512/256/128”
Table 37-7, “Power Consumption for Different Modes”
Table 37-8, “Power Consumption on VDDCORE(1)”
Table 37-10, “Main Oscillator Characteristics”
Table 37-11, “Crystal Characteristics” has been added.
Table 37-12, “XIN Clock Electrical Characteristics”
Table 37-13, “Phase Lock Loop Characteristics”
Table 37-22, “SPI Timings”
Review
Section 37. ”SAM7S Electrical Characteristics”
“Absolute Maximum Ratings” on page 557, change to Maximum Operating Voltages.
Table 37-7, “Power Consumption for Different Modes”, note added to table
#3058
#3061
Section 38. ”Mechanical Characteristics” SAM7S512 added to Device and Package weights
Section 40. ”Errata” Added Section 40.1 ”Marking”
TWI: Behavior of OVRE bit: eliminated.
change or added to all:
PIO: Leakage on PA17 - PA20...” the leakage can be 9 µA in worst case...”
RTT: Possible Event Loss when Reading RTT_SR
SPI: Chip Select and Fixed Mode
SPI: Baudrate Set to 1
SPI: Disable in Slave Mode
TWI: Software Reset
USART: Hardware Handshaking – Two Characters are Sent
USART: XOFF Character Bad Behavior
added to AT91SAM7S64/32 only:
SPI: Disable Issue
SPI: Software Reset and SPIEN Bit
SPI: CSAAT = 1 and Delay
Change to AT91SAM7S321 only:
Voltage Regulator errata removed.
PWM: Constraints on Duty Cycle Value, updated all 3173
Version
6175F Comments (Continued)
Change
Request
Ref.
763
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175E Comments
Change
Request
Ref
“Features” on page 1, Table 1-1, “Configuration Summary,” on page 3, Section 4. ”Package and
Pinout”“Absolute Maximum Ratings” on page 557, Table 37-1, “Thermal Resistance Data,” on
page 537and
Section 39. ”SAM7S Ordering Information”QFN package information added.
Section 40. ”Errata” QFN package errata added,
Section 40. ”Errata” SPI: SPCK Behavior in Master Mode added.
Section 40. ”Errata” PIO: Leakage in worst case changed to 9 µA.
#2403
#2453
#2607
Version
6175D Comments
Change
Request
Ref
Section 40.20 ”SAM7S321 Errata - Revision A Parts” added
#1768
Section 40. ”Errata” added the following:
Section 40.6.11.3 ”TWI: Disabling Does not Operate Correctly” AT91SAM7S256
Section 40.6.11.4 ”TWI: NACK Status Bit Lost”
Section 40.6.11.5 ”TWI: Possible Receive Holding Register Corruption”
Section 40.6.12.1 ”USART: CTS in Hardware Handshaking”
Section 40.11.11.3 ”TWI: Disabling Does not Operate Correctly”AT91SAM7S128
Section 40.11.11.4 ”TWI: NACK Status Bit Lost”
Section 40.11.11.5 ”TWI: Possible Receive Holding Register Corruption”
Section 40.11.12.1 ”USART: CTS in Hardware Handshaking”
Section 40.16.10.3 ”TWI: Disabling Does not Operate Correctly”AT91SAM7S64
Section 40.16.10.4 ”TWI: NACK Status Bit Lost”
Section 40.16.10.5 ”TWI: Possible Receive Holding Register Corruption”
Section 40.16.11.2 ”USART: CTS in Hardware Handshaking”
Section 40.21.9.3 ”TWI: Disabling Does not Operate Correctly”AT91SAM7S32
Section 40.21.9.4 ”TWI: NACK Status Bit Lost”
Section 40.21.9.5 ”TWI: Possible Receive Holding Register Corruption”
Section 40.21.10.2 ”USART: CTS in Hardware Handshaking”
Section 40.7 ”SAM7S256 Errata - Revision A Parts” added
Section 40.12 ”SAM7S128 Errata - Revision A Parts” added #2309
Section 39. ”SAM7S Ordering Information” AT91SAM7S321 changed in Table 39-1 on page 586 #2343
764
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175C Comments
Change
Request
Ref
AT91SAM7S321 addresses redefined:Table 22-4, “User Area Addresses,” on page 171
Values given in PIO Line column: Table 22-5, “Pins Driven during Boot Program Execution,” on page 171 #1217
Section 40. ”Errata” added lines and note to the following:
Section 40.6.3.1 ”MCK: Limited Master Clock Frequency Ranges” AT91SAM7S256
Section 40.11.3.1 ”MCK: Limited Master Clock Frequency Ranges” AT91SAM7S128
Section 40.16.3.1 ”MCK: Limited Master Clock Frequency Ranges” AT91SAM7S64
Section 40.21.3.1 ”MCK: Limited Master Clock Frequency Ranges” AT91SAM7S32
and
Section 40.6.4.1 ”NVM Bits: Write/Erase Cycles Number” AT91SAM7S256
Section 40.11.4.1 ”NVM Bits: Write/Erase Cycles Number” AT91SAM7S128
Section 40.16.4.1 ”NVM Bits: Write/Erase Cycles Number” AT91SAM7S64
Section 40.21.4.1 ”NVM Bits: Write/Erase Cycles Number” AT91SAM7S32
#1547 and
review
note (2) added to Table 37-24, “Embedded Flash Wait States,” on page 582 review
”Voltage Regulator Mode Register” page 118, bit field name corrected ”PSTDBY: Power Standby Mode” #1585
AT91SAM7S321 addresses redefined:Table 22-4, “User Area Addresses,” on page 171
Values given in PIO Line column: Table 22-5, “Pins Driven during Boot Program Execution,” on page 171 #1217
Version
6175B Comments
Change
Request
Ref
Added to datasheet: Section 40. “Errata” on page 595
Section 40.6 “SAM7S256 Errata - Manufacturing Number 58818C” on page 614,Section 40.11
“SAM7S128 Errata - Manufacturing Number 58818C” on page 646, Section 40.16 “SAM7S64 Errata -
Manufacturing Number 58814G” on page 678 Section 40.21 “SAM7S32 Errata - Manufacturing Number
58814G” on page 716
Changes/updates to the following:
“ADC Characteristics” on page 574, Figure 37-5 and Figure 37-6 on page 576, Table 37-6, “DC Flash
Characteristics SAM7S512/256/128,” on page 560 and Table 37-13, “Phase Lock Loop Characteristics,”
on page 570
05-501
update to “Internal Memory Mapping” on page 98 05-507
update to SVMST0: Saved PDC Abort Source and SVMST1: Saved ARM7TDMI Abort Source register
field definitions in “MC Abort Status Register” on page 103.05-509
Section 8. “Memories” on page 18 updated: 2 ms => 3 ms, 10 ms => 15 ms, 4 ms => 6 ms 05-529
Evolution in IP blocks:
EFC: FMCN: Flash Microsecond Cycle Number register field in ”MC Flash Mode Register” page 138
PMC: Section 26.7 ”Programming Sequence” page 215
DBGU: ”ARCH: Architecture Identifier” page 259 register field in “Debug Unit Chip ID Register”
SPI: Section 28. ”Serial Peripheral Interface (SPI)” page 1
UDP: Section 34.3.2 ”Power Management” page 445, Section 34.6 ”USB Device Port (UDP) User
Interface” page 462, ”UDP Transceiver Control Register” page 478
In Features and global: ”EmbeddedICE™ In-circuit Emulation, Debug Communication Channel Support”
EmbeddedICE to replace usage of “embedded in-ciruit emulator”
765
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Version
6175A Comments
Change
Request
Ref
First issue
766
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
767
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
Table of Contents
Features ..................................................................................................... 1
1 Description ................................................................................................ 3
1.1Configuration Summary of the SAM7S512, SAM7S256, SAM7S128, SAM7S64, SAM7S321, SAM7S32,
SAM7S161 and SAM7S16 3
2 Block Diagram .......................................................................................... 4
3 Signal Description .................................................................................... 6
4 Package and Pinout ................................................................................. 9
4.164-lead LQFP and 64-pad QFN Package Outlines ...................................................9
4.264-lead LQFP and 64-pad QFN Pinout ...................................................................10
4.348-lead LQFP and 48-pad QFN Package Outlines .................................................11
4.448-lead LQFP and 48-pad QFN Pinout ...................................................................11
5 Power Considerations ........................................................................... 12
5.1Power Supplies ........................................................................................................12
5.2Power Consumption ................................................................................................12
5.3Voltage Regulator ....................................................................................................12
5.4Typical Powering Schematics ..................................................................................12
6 I/O Lines Considerations ....................................................................... 14
6.1JTAG Port Pins ........................................................................................................14
6.2Test Pin ...................................................................................................................14
6.3Reset Pin .................................................................................................................14
6.4ERASE Pin ..............................................................................................................14
6.5PIO Controller A Lines .............................................................................................14
6.6I/O Line Drive Levels ...............................................................................................14
7 Processor and Architecture .................................................................. 16
7.1ARM7TDMI Processor .............................................................................................16
7.2Debug and Test Features ........................................................................................16
7.3Memory Controller ...................................................................................................16
7.4Peripheral DMA Controller .......................................................................................17
8 Memories ................................................................................................. 18
8.1SAM7S512 ..............................................................................................................18
8.2SAM7S256 ..............................................................................................................18
8.3SAM7S128 ..............................................................................................................18
8.4SAM7S64 ................................................................................................................18
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SAM7S Series [DATASHEET]
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8.5SAM7S321/32 .........................................................................................................19
8.6SAM7S161/16 .........................................................................................................19
8.7Memory Mapping .....................................................................................................21
8.8Embedded Flash .....................................................................................................22
8.9Fast Flash Programming Interface ..........................................................................25
8.10SAM-BA Boot Assistant .........................................................................................25
9 System Controller .................................................................................. 25
9.1Reset Controller .......................................................................................................28
9.2Clock Generator ......................................................................................................29
9.3Power Management Controller ................................................................................29
9.4Advanced Interrupt Controller ..................................................................................30
9.5Debug Unit ...............................................................................................................31
9.6Periodic Interval Timer .............................................................................................31
9.7Watchdog Timer ......................................................................................................31
9.8Real-time Timer .......................................................................................................32
9.9PIO Controller ..........................................................................................................32
9.10Voltage Regulator Controller .................................................................................32
10 Peripherals .............................................................................................. 33
10.1User Interface ........................................................................................................33
10.2Peripheral Identifiers ..............................................................................................33
10.3Peripheral Multiplexing on PIO Lines ....................................................................34
10.4PIO Controller A Multiplexing ................................................................................35
10.5Serial Peripheral Interface .....................................................................................37
10.6Two-wire Interface .................................................................................................37
10.7USART ..................................................................................................................37
10.8Serial Synchronous Controller ...............................................................................38
10.9Timer Counter ........................................................................................................38
10.10PWM Controller ...................................................................................................38
10.11USB Device Port (Does not pertain to SAM7S32/16) ..........................................39
10.12Analog-to-digital Converter ..................................................................................39
11 ARM7TDMI Processor Overview ........................................................... 41
11.1Overview ................................................................................................................41
11.2ARM7TDMI Processor ...........................................................................................42
12 Debug and Test Features ...................................................................... 47
12.1Description .............................................................................................................47
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12.2Block Diagram .......................................................................................................47
12.3Application Examples ............................................................................................48
12.4Debug and Test Pin Description ............................................................................50
12.5Functional Description ...........................................................................................51
13 Reset Controller (RSTC) ........................................................................ 57
13.1Overview ................................................................................................................57
13.2Block Diagram .......................................................................................................57
13.3Functional Description ...........................................................................................58
13.4Reset Controller (RSTC) User Interface ................................................................67
14 Real-time Timer (RTT) ............................................................................ 73
14.1Overview ................................................................................................................73
14.2Block Diagram .......................................................................................................73
14.3Functional Description ...........................................................................................73
14.4Real-time Timer (RTT) User Interface ...................................................................75
15 Periodic Interval Timer (PIT) .................................................................. 81
15.1Overview ................................................................................................................81
15.2Block Diagram .......................................................................................................81
15.3Functional Description ...........................................................................................82
15.4Periodic Interval Timer (PIT) User Interface ..........................................................83
16 Watchdog Timer (WDT) .......................................................................... 89
16.1Overview ................................................................................................................89
16.2Block Diagram .......................................................................................................89
16.3Functional Description ...........................................................................................90
16.4Watchdog Timer (WDT) User Interface .................................................................92
17 Voltage Regulator Mode Controller (VREG) ........................................ 95
17.1Overview ................................................................................................................95
17.2Voltage Regulator Power Controller (VREG) User Interface .................................96
18 Memory Controller (MC) ........................................................................ 97
18.1Overview ................................................................................................................97
18.2Block Diagram .......................................................................................................97
18.3Functional Description ...........................................................................................97
18.4Memory Controller (MC) User Interface ..............................................................100
19 Embedded Flash Controller (EFC) ...................................................... 105
19.1Overview .............................................................................................................105
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19.2Functional Description .........................................................................................105
19.3Embedded Flash Controller (EFC) User Interface ...............................................114
20 Fast Flash Programming Interface (FFPI) .......................................... 123
20.1Overview ..............................................................................................................123
20.2Parallel Fast Flash Programming ........................................................................124
20.3Serial Fast Flash Programming ...........................................................................136
21 SAM7 Boot Program ............................................................................ 143
21.1Description ...........................................................................................................143
21.2Flow Diagram ......................................................................................................143
21.3Device Initialization with USB ..............................................................................144
21.4Device Initialization without USB .........................................................................144
21.5SAM-BA Boot ......................................................................................................145
21.6Hardware and Software Constraints ....................................................................150
22 Peripheral DMA Controller (PDC) ....................................................... 151
22.1Overview ..............................................................................................................151
22.2Block Diagram .....................................................................................................151
22.3Functional Description .........................................................................................152
22.4Peripheral DMA Controller (PDC) User Interface ...............................................153
23 Advanced Interrupt Controller (AIC) ................................................... 161
23.1Overview ..............................................................................................................161
23.2Block Diagram .....................................................................................................161
23.3Application Block Diagram ...................................................................................162
23.4AIC Detailed Block Diagram ................................................................................162
23.5I/O Line Description .............................................................................................162
23.6Product Dependencies ........................................................................................163
23.7Functional Description .........................................................................................164
23.8Advanced Interrupt Controller (AIC) User Interface .............................................175
24 Clock Generator ................................................................................... 187
24.1Overview ..............................................................................................................187
24.2Slow Clock RC Oscillator .....................................................................................187
24.3Main Oscillator .....................................................................................................187
24.4Divider and PLL Block .........................................................................................189
25 Power Management Controller (PMC) ................................................ 191
25.1Description ...........................................................................................................191
25.2Master Clock Controller .......................................................................................191
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25.3Processor Clock Controller ..................................................................................191
25.4USB Clock Controller ...........................................................................................192
25.5Peripheral Clock Controller ..................................................................................192
25.6Programmable Clock Output Controller ...............................................................192
25.7Programming Sequence ......................................................................................193
25.8Clock Switching Details .......................................................................................197
25.9Power Management Controller (PMC) User Interface ........................................200
26 Debug Unit (DBGU) .............................................................................. 215
26.1Overview ..............................................................................................................215
26.2Block Diagram .....................................................................................................216
26.3Product Dependencies ........................................................................................217
26.4UART Operations ................................................................................................217
26.5Debug Unit (DBGU) User Interface ....................................................................224
27 Parallel Input/Output Controller (PIO) ................................................ 239
27.1Overview ..............................................................................................................239
27.2Block Diagram .....................................................................................................240
27.3Product Dependencies ........................................................................................241
27.4Functional Description .........................................................................................242
27.5I/O Lines Programming Example .........................................................................246
27.6Programmable Multibit ECC Error Location (PIO) User Interface .......................248
28 Serial Peripheral Interface (SPI) .......................................................... 269
28.1Overview ..............................................................................................................269
28.2Block Diagram .....................................................................................................269
28.3Application Block Diagram ...................................................................................270
28.4Signal Description ...............................................................................................270
28.5Product Dependencies ........................................................................................270
28.6Functional Description .........................................................................................272
28.7Serial Peripheral Interface (SPI) User Interface User Interface ...........................281
29 Two-wire Interface (TWI) SAM7S512/256/128/64/321/32 .................... 295
29.1Overview ..............................................................................................................295
29.2List of Abbreviations ............................................................................................295
29.3Block Diagram .....................................................................................................296
29.4Application Block Diagram ...................................................................................296
29.5Product Dependencies ........................................................................................296
29.6Functional Description .........................................................................................297
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29.7Two-wire Interface (TWI) User Interface .............................................................309
30 Two Wire Interface (TWI) SAM7S161/16 ............................................. 319
30.1Overview ..............................................................................................................319
30.2List of Abbreviations ............................................................................................319
30.3Block Diagram .....................................................................................................320
30.4Application Block Diagram ...................................................................................320
30.5Product Dependencies ........................................................................................320
30.6Functional Description .........................................................................................321
30.7Master Mode ........................................................................................................323
30.8Multi-master Mode ...............................................................................................334
30.9Slave Mode ..........................................................................................................337
30.10Two-wire Interface (TWI) User Interface ...........................................................345
31 Universal Synchronous Asynchronous Receiver Transceiver (USART) 359
31.1Overview ..............................................................................................................359
31.2Block Diagram .....................................................................................................360
31.3Application Block Diagram ...................................................................................361
31.4I/O Lines Description ..........................................................................................362
31.5Product Dependencies ........................................................................................363
31.6Functional Description .........................................................................................364
31.7Universal Synchronous Asynchronous Receiver Transmitter (USART) User Interface 388
32 Synchronous Serial Controller (SSC) ................................................. 409
32.1Description ...........................................................................................................409
32.2Block Diagram .....................................................................................................409
32.3Application Block Diagram ...................................................................................410
32.4Pin Name List ......................................................................................................410
32.5Product Dependencies ........................................................................................410
32.6Functional Description .........................................................................................410
32.7SSC Application Examples ..................................................................................420
32.8Syncrhronous Serial Controller (SSC) User Interface .........................................423
33 Timer Counter (TC) ............................................................................... 447
33.1Overview ..............................................................................................................447
33.2Block Diagram .....................................................................................................448
33.3Pin Name List ......................................................................................................449
33.4Product Dependencies ........................................................................................449
33.5Functional Description .........................................................................................450
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33.6Timer Counter (TC) User Interface ......................................................................463
34 Pulse Width Modulation Controller (PWM) ........................................ 481
34.1overview ..............................................................................................................481
34.2Block Diagram .....................................................................................................481
34.3I/O Lines Description ...........................................................................................482
34.4Product Dependencies ........................................................................................482
34.5Functional Description .........................................................................................482
34.6Pulse Width Modulation Controller (PWM) User Interface ..................................489
35 USB Device Port (UDP) ........................................................................ 501
35.1Overview ..............................................................................................................501
35.2Block Diagram .....................................................................................................501
35.3Product Dependencies ........................................................................................503
35.4Typical Connection ..............................................................................................504
35.5Functional Description .........................................................................................505
35.6USB Device Port (UDP) User Interface ...............................................................518
36 Analog-to-Digital Converter (ADC) ..................................................... 539
36.1Overview ..............................................................................................................539
36.2Block Diagram .....................................................................................................539
36.3Signal Description ................................................................................................540
36.4Product Dependencies ........................................................................................540
36.5Functional Description .........................................................................................541
36.6Analog-to-Digital Converter (ADC) User Interface ...............................................546
37 SAM7S Electrical Characteristics ....................................................... 557
37.1Absolute Maximum Ratings .................................................................................557
37.2DC Characteristics ...............................................................................................558
37.3Power Consumption ............................................................................................560
37.4Crystal Oscillators Characteristics .......................................................................567
37.5PLL Characteristics .............................................................................................570
37.6Master Clock Characteristics ...............................................................................570
37.7I/O Characteristics ...............................................................................................570
37.8USB Transceiver Characteristics .........................................................................572
37.9ADC Characteristics ...........................................................................................574
37.10AC Characteristics .............................................................................................576
38 Mechanical Characteristics ................................................................. 585
38.1Package Drawings ...............................................................................................585
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38.2LQFP Packages ..................................................................................................585
38.3QFN Packages ....................................................................................................588
38.4Soldering Profile ..................................................................................................592
39 SAM7S Ordering Information .............................................................. 593
40 Errata ..................................................................................................... 595
40.1Marking ................................................................................................................595
40.2Errata Summary by Product and Revision or Manufacturing Number .................596
40.3Errata Organization by Product and Revision or Manufacturing Number ............597
40.4SAM7S512 Errata - Revision A Parts ..................................................................599
40.5SAM7S512 Errata - Revision B Parts ..................................................................606
40.6SAM7S256 Errata - Manufacturing Number 58818C ..........................................614
40.7SAM7S256 Errata - Revision A Parts ..................................................................624
40.8SAM7S256 Errata - Revision B Parts ..................................................................634
40.9SAM7S256 Errata - Revision C Parts ..................................................................642
40.10SAM7S256 Errata - Revision D Parts ................................................................644
40.11SAM7S128 Errata - Manufacturing Number 58818C ........................................646
40.12SAM7S128 Errata - Revision A Parts ................................................................656
40.13SAM7S128 Errata - Revision B Parts ................................................................666
40.14SAM7S128 Errata - Revision C Parts ................................................................674
40.15SAM7S128 Errata - Revision D Parts ................................................................676
40.16SAM7S64 Errata - Manufacturing Number 58814G ..........................................678
40.17SAM7S64 Errata - Revision A Parts ..................................................................688
40.18SAM7S64 Errata - Revision B Parts ..................................................................697
40.19SAM7S64 Errata - Revision C Parts ..................................................................706
40.20SAM7S321 Errata - Revision A Parts ................................................................708
40.21SAM7S32 Errata - Manufacturing Number 58814G ..........................................716
40.22SAM7S32 Errata - Revision A Parts ..................................................................725
40.23SAM7S32 Errata - Revision B Parts ..................................................................734
40.24SAM7S161 Errata - Revision A Parts ................................................................742
40.25SAM7S16 Errata - Revision A Parts ..................................................................747
Revision History .................................................................................... 753
Table of Contents .................................................................................. 767
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