CP2102
12 Rev. 1.4
5. Asynchronous Serial Data Bus (UART) Interface
The CP2102 UART interface consists of the TX (transmit) and RX (r eceive) d ata signals as well as the RTS, CTS,
DSR, DTR, DCD, and RI control signals. The UART supports RTS/CTS, DSR/DTR, and X-On/X-Off handshaking.
The UART is programmab le to su pport a vari ety of data formats and baud rates. If the V i rtual COM Port drive rs are
used, the dat a format and b aud rate are set dur ing COM port configuration on the PC. If the USBXpress drivers are
used, the CP2102 is configured through the USBXpress API. The data formats and baud rates available are listed
in Ta ble 8.
6. Internal EEPROM
The CP2102 includes an internal EEPROM that may be used to customize the USB Vendor ID (VID), Product ID
(PID), Product Description String, Power Descriptor, Device Release Number and Device Serial Number as
desired for OEM applications. If the EEPROM is not programmed with OEM data, the default configuration data
shown in Table 9 is used.
While customization of the USB configuration data is optional, it is recommended to customize the VID/PID
combination. A unique VID/PID combination will prevent the driver from conflicting with any other USB driver. A
vendor ID can be obtained from http://www.usb.org/ or Silicon Laboratories can provide a free PID for the OEM
product that can be used with the Silicon Laboratories VID. It is also recommended to customize the serial number
if the OEM application is one in which it is possible for multiple CP2102-based devices to be connected to the
same PC.
The internal EEPROM is programmed via the USB. This allows the OEM's USB configuration data and serial
number to be written to the CP2102 on-board during the manufacturing and testing process. A stand-alone utility
for programming the internal EEPROM is available from Silicon Laboratories. A library of routines provided in the
form of a Windows® DLL is also available. This library can be used to integrate the EEPROM programming step
into custom sof twa re used by the OEM to str eamline testin g and serial numb er managemen t during manufacturing.
The EEPROM has a typical endurance of 100,000 write cycles with a data retention of 100 years.
USB descriptors can be locked to prevent future modification.
Table 8. Data Formats and Baud Rates
Data Bits 5, 6, 7, and 8
Stop Bits 1, 1.51, and 2
Parity Type None, Even, Odd, Mark, Space
Baud Rates2300, 600, 1200, 1800, 2400, 4000, 4800, 7200, 9600, 14400, 16000, 19200 , 28800,
38400, 51200, 56000, 57600, 64000, 76800, 115200, 128000, 153600, 230400, 250000,
256000, 460800, 500000, 576000, 9216003
Notes:
1. 5-bit only.
2. Additional baud rates are supported. See “AN205”.
3. 7 or 8 data bits only.