© 2014 Exar Corporation
XR21B1421
32 / 50 exar.com/XR21B1421
Rev 1B
GET / SET_CHIP_ID
Transfer Type: Control In / Out
Transfer Size: 7 bytes
The GET / SET_CHIP_ID report reports Exar’s device manufacturer’s USB Vendor and Product IDs (VID and PID) irrespec-
tive of any changes to the VID and PID using the SET_USB_CONFIG report. (However, values from the SET_USB_CON-
FIG report will be reported to the USB host during device enumeration.)
GET / SET_UART_CONFIG
Transfer Type: Control In / Out
Transfer Size: 9 bytes
The GET / SET_UART_CONFIG report gets or sets baud rate, parity, flow control mode, and number of data and stop bits
as well as controls auto-RS-485 half-duplex and hardware flow control modes.
Field Offset Size Value Description
Report ID 0 1 0x4F Get Chip ID
VID Chip LSB 1 1 0xE2 LSB of Exar Vendor VID
VID Chip MSB 2 1 0x04 MSB of Exar Vendor PID
PID Chip LSB 3 1 0x21 LSB of Exar Vendor PID
PID Chip MSB 4 1 0x14 MSB of Exar Vendor VID
Chip Revision 5 1 0x02 Device revision
Reserved 6 1 0x00 Reserved, return 0x00
Field Offset Size Value Description
Report ID 0 1 0x50 Get or set UART configuration
Baud Rate 3 1 1 Baud[31:24] OTP programmed fields
Baud Rate 2 2 1 Baud[23:16] Baud: Any integer value from 300 (0x0000012C) to 12,000,000 (0x00B71B00) is a
valid baud rate. The default baud rate is 115,200 bps.
Baud Rate 1 3 1 Baud[15:8]
Baud Rate 0 4 1 Baud[7:0]
Parity 5 1 0x00 No Parity (Default)
0x01 Even Parity
0x02 Odd Parity
0x03 Mark Parity
0x04 Space Parity
Data Control 6 1 See Ta bl e 14 Control flow control mode, RS-485 half-duplex mode select and polarity, and duplex
