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PIN NAME FUNCTION
78 A0
Port 7, I/O. Port 7 can function as either an 8-bit, bidirectional I/O port or the nonmultiplexed A0–A7 signals
(when the MUX pin = 1). The reset condition of Port 7 is all bits at logic 1 through a weak pullup. The logic 1
state also serves as an input mode, since external circuits writing to the port can override the weak pullup.
When software clears any port pin to 0, a strong pulldown is activated that remains on until either a 1 is written
to the port pin or a reset occurs. Writing a 1 after the port has been at 0 activates a strong transition driver,
followed by a weaker sustaining pullup. Once the momentary strong driver turns off , the port once again
becomes the output (and input) high state.
Port Alt ernat e Function
P7.0 A0 Program/Data Memory Address 0
P7.1 A1 Program/Data Memory Address 1
P7.2 A2 Program/Data Memory Address 2
P7.3 A3 Program/Data Memory Address 3
P7.4 A4 Program/Data Memory Address 4
P7.5 A5 Program/Data Memory Address 5
P7.6 A6 Program/Data Memory Address 6
P7.7 A7 Program/Data Memory Address 7
77 A1
76 A2
75 A3
74 A4
73 A5
72 A6
71 A7
8 TXClk
Transmit Clock, Input. The transmit clock is a continuous clock sourced from t he Ethernet PHY controller. It is
used to provide timing reference for transf erring of TX_EN and TXD[3:0] signals from the MAC to the external
Ethernet PHY controller. The i nput clock frequency of TXClk shoul d be 25MHz for 100Mbps operation and
2.5MHz for 10Mbps operation. For ENDEC operation, TXClk serves the same funct i on, but the input clock
frequency shoul d be 10MHz.
7 TX_EN
Transmit Enable, Output. The transmit enable is an active-high output and is synchronous with respect to the
TXClk signal. TX_EN is used to indicate valid nibbles of data for transm ission on the MII pins TXD.3–TXD.0.
TX_EN is asserted with the first nibble of the preamble and remains assert ed while all nibbles to be transmitted
are presented on the TXD.3–TXD.0 pins. TX_EN negates prior t o the first TXClk foll owing the final nibble of the
frame. TX_EN serves the same function for ENDEC operation.
Transmit Data, Output. The transmit data outputs provide 4-bit nibbles of data for transmiss i on over the MII.
The transmit data is synchronous with respec t t o the TXClk signal. For each TXClk period when TX_EN is
asserted, TXD.3–TXD.0 provides the data for transmission to the Ethernet PHY controller. When TX_EN is
deassert ed, the TXD data should be ignored. For ENDEC operation, only TXD.0 is used for transmission of
6 TXD.0
10 RXClk
Receive Clock, Input. The receive clock is a continuous clock sourced from the Ethernet PHY controller. It is
used to provide timing reference for transf erri ng of RX_DV, RX_ER, and RXD[3:0] signals from the external
Ethernet PHY controller to t he MAC. The input clock frequency of RXClk should be 25MHz for 100Mbps
operation and 2.5MHz for 10Mbps operation. For ENDEC operation, RXClk serves the sam e function, but t he
input clock frequency should be 10MHz.
11 RX_DV
Receive Data Valid, Input. The receive dat a valid is an active-high input from t he external Ethernet PHY
controll er and is synchronous with respec t t o the RXClk signal. RX_DV is used to indicate valid nibbl es of data
for reception on the MII pins RXD.3–RXD.0. RX_DV is asserted continuously from the fi rst nibble of the frame
through the final nibbl e. RX_DV negates pri or to the first RXClk foll owing the final ni bbl e. RX_DV serves the
same function for ENDEC operation.
9 RX_ER
Receive Error, Input. The recei ve error is an active-high input from the external Ethernet PHY controller and is
synchronous with respect to the RXClk signal. RX_ER is used to indicate to the MAC that an error (e.g., a
coding error, or any error detect able by the PHY) was detected somewhere in the frame presentl y bei ng
transmitted by the PHY. RX_ER has no effect on the MAC while RX_DV is deasserted. RX_ER should be low
Receive Data, Input. The receive data inputs provide 4 -bit nibbl es of data for rec eption over t he MII. The
receive data is synchronous with respect to t he RXClk signal. For each RXClk period when RX_DV is asserted,
RXD.3–R XD.0 have the dat a to be received by the MAC. When RX_DV is deasserted, the RXD data should be
ignored. For ENDEC operation, only RXD.0 is used for recepti on of frames.
1 CRS
Carrier Sense, Input. The carrier sense signal is an active-high input and should be asserted by the external
Ethernet PHY controller when either the t ransmit or receive m edium is not idl e. CRS should be deasserted by
the PHY when the transmit and receive mediums are idle. The PHY should ensure that the CRS signal remains
assert ed throughout the durat i on of a collision condition. The transiti ons on the CRS signal need not be
synchronous to TXClk or RXClk. CRS serves t he same function for ENDEC operati on.
2 COL
Collision Detec t , Input . The collision detect signal is an active-high input and should be asserted by the
external Ethernet P HY controll er upon detecti on of a collis i on on the medium. The PHY should ensure that COL
remains asserted while the col lis i on conditi on pers ists. The transitions on the COL signal need not be
synchronous to TXClk or RXClk. The COL signal is ignored by the MAC when operating in full-duplex mode.
COL serves the same function for ENDEC operation.
18 MDC
MII Management Clock, Output. The MII management clock is generated by the MAC for use by the external
Ethernet PHY controller as a timing referenced for t ransf erring i nformation on the MDIO pin. MDC is a periodic
signal that has no maximum high or low times. The minimum high and low times are 160ns each. The minimum
period for MDC is 400ns independent of the period of TXClk and RXClk.
19 MDIO
MII Management Input/ O utput . The MII management I/O is the data pin for serial communication with the
external Ethernet P HY controll er. In a read cycle, dat a is driven by the PHY to the MAC synchronously with
respect to the MDC clock. In a write cycle, data from the MAC is output to the external PHY sync hronously with
respect to the MDC clock.
99 OW
1-Wire Da t a , I/O. The 1-W i re data pin is an open-drain, bidirectional data bus for the 1-Wire Bus Master.
External 1-Wire slave devic es are connec t ed to this pin. This pin must be pulled high by an external resistor,