XR22801 Datasheet, PDF (22/42 Pages) Exar Corporation – Hi-Speed USB to 10/100 Ethernet Bridge

XR22801
RS485_DELAY (0x04B) - Read/Write
Bit
15:4
3:0
Default
Description
0x000
Reserved
These bits are reserved and should be written as ‘0’.
000
Value
This value is the number of bit times the XR22801 waits before de-asserting the E5/RTS#/RS485/G5 pin when
it is configured for automatic RS-485 half-duplex control.
GPIO_MODE (0x04C) - Read/Write
Bit
15:4
3
2:0
Default
Description
0x000
0
Reserved
These bits are reserved and should be written as ‘0’.
RS485 Polarity
0: Active low auto. RS-485 half-duplex enable
1: Active high auto. RS-485 half-duplex enable
0x0
GPIO Mode
000: Mode 0 - All GPIO are used for general purpose I/O.
001: Mode 1 - E5/RTS#/RS485/G5 and E4/CTS#/G4 used for Auto RTS/CTS HW Flow Control
010: Mode 2 - E3/DTR#/G3 and E2/DSR#/G2 used for Auto DTR/DSR HW Flow Control
011: Mode 3 - E5/RTS#/RS485/G5 pin used for auto RS-485 half-duplex enable during Transmit
100: Mode 4 - E5/RTS#/RS485/G5 pin used for auto RS-485 half-duplex enable after address match.
101 to 111: Reserved values, do not use.
GPIO_DIRECTION (0x04D) - Read/Write
Note that when setting direction of a UART GPIO to output, the PIN_PULLUP_EN for that IO pin should also be disabled
and when setting a UART GPIO pin to input, the PIN_PULLUP_EN for that IO pin should also be enabled.
Bit
15:6
5:0
Default
Description
0x000
Reserved
These bits are reserved and should be written as ‘0’.
0x00
GPIO[N] Direction
0: GPIO[N] is an input
1: GPIO[N] is an output
GPIO_SET (0x04E) - Write Only
Bit
15:6
Default
Description
0x000
Reserved
These bits are reserved and should be written as ‘0’.
© 2015 Exar Corporation
22 / 42
exar.com/XR22801
Rev 1B