XR21B1422IL40-0A Datasheet, PDF (43/60 Pages) Exar Corporation – Enhanced 2-Ch Full-Speed USB UART

XR21B1422
CDC_ACM_FLOW (0x008) - Read/Write OTP
Bit
15:4
3
2:0
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
0
UART Half-Duplex Mode
0: Normal (full-duplex) mode. The UART can transmit and receive data at the same time.
1: UART Half-Duplex Mode. In half-duplex mode, any data on the RX pin is ignored when the UART is transmitting data.
000
Mode
000: Mode 0. No flow control, no address matching.
001: Mode 1. HW flow control enabled. Auto RTS/CTS or DTR/DSR must be selected by GPIO_MODE.
010: Mode 2. SW flow control enabled.
011: Mode 3. Multidrop mode - RX only after address match, TX independent. (Typically used with GPIO_MODE 3).
100: Mode 4. Multidrop mode - RX/TX only after address match. (Typically used with GPIO_MODE 4).
101 to 111: Reserved
CDC_ACM_MODE_LSB (0x009) - Read/Write OTP
Bit
7
6:5
4
3
2:0
Default
Description
0
Clock Enable
0: GPIO6 is used for general purpose I/O
1: GPIO6 is used to output a clock.
0
Auto RS-485 Half-Duplex Select
00: GPIO. GPIO7/RS485 is used for general purpose I/O
01: RS485_EN_ACT. GPIO7/RS485 is used for auto RS-485 half-duplex enable. Asserted whenever the UART is transmitting
10: RS485_EN_FLOW. GPIO7/RS485 is used for auto RS-485 half-duplex enable. Asserted for the duration of the address
match
11: RESERVED. Reserved value, do not use
0
Auto RS-485 Half-Duplex Pin
0: GPIO5/RTS#/RS485 function is selected by GPIO_MODE[2:0]. GPIO7/RS485 function is GPIO.
1: GPIO7/RS485 function is selected by GPIO_MODE[6:5]. GPIO5/RTS#/RS485 function must be any function other than
that selected for GPIO7/RS485.
0
Auto RS-485 Half-Duplex Polarity
0: GPIO5/RTS#/RS485 function is selected by GPIO_MODE[2:0]. GPIO7/RS485 function is GPIO.
1: GPIO7/RS485 function is selected by GPIO_MODE[6:5]. GPIO5/RTS#/RS485 function must be any function other than
that selected for GPIO7/RS485.
0
GPIO Mode Select
000: GPIO. RTS/CTS and DTR/DSR are used for general purpose I/O.
001: RTS_CTS. GPIO4 and GPIO5 used for Auto RTS/CTS HW Flow Control
010: DTR_DSR. GPIO2 and GPIO3 used for Auto DTR/DSR HW Flow Control
011: RS485_EN_ACT. GPIO5/RTS#/RS485 pin used for auto .RS-485 half-duplex enable during Transmit
100: RS485_EN_FLOW. GPIO5/RTS#/RS485 pin used for auto RS-485 half-duplex enable after address match.
101 to 111: Reserved. Reserved value, do not use.
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Rev 1A