XR21B1422IL40-0A Datasheet, PDF (53/60 Pages) Exar Corporation – Enhanced 2-Ch Full-Speed USB UART

XR21B1422
PIN_CFG_RXT (0x029) - Read/Write OTP
This register configures the functionality of the GPIO9/RXT pin
Bit
7
6
5:2
1:0
Default
Description
0
PULLUP_EN
This register bit is used to enable the internal pull-up resistor. This setting will be ignored if GPIO9/RXT is configured as an
output.
0: Do not enable internal pull-up
1: Enable internal pull-up if configured as an input
0
PULLDOWN_EN
This register bit is used to enable the internal pull-down resistor. This setting will be ignored if GPIO9/RXT is configured as an
output.
0: Do not enable internal pull-down
1: Enable internal pull-down if configured as an input (will not be enabled if Pull up is enabled)
0
RESERVED
These bits are reserved and should be written as ’0’.
0
CTRL
000: GPIO9/RXT is configured as a GPIO input
001: GPIO9/RXT is configured as a GPIO open drain output
010: GPIO9/RXT is configured as a GPIO push-pull output
011: GPIO9/RXT is configured as a push-pull RX toggle output
PIN_CFG_CD (0x02A) - Read/Write OTP
This register configures the functionality of the GPIO1/CD pin
Bit
7
6
5:2
1:0
Default
Description
0
PULLUP_EN
This register bit is used to enable the internal pull-up resistor. This setting will be ignored if GPIO1/CD# is configured as an
output.
0: Do not enable internal pull-up
1: Enable internal pull-up if configured as an input
0
PULLDOWN_EN
This register bit is used to enable the internal pull-down resistor. This setting will be ignored if GPIO1/CD# is configured as an
output.
0: Do not enable internal pull-down
1: Enable internal pull-down if configured as an input (will not be enabled if Pull up is enabled)
0
RESERVED
These bits are reserved and should be written as ’0’.
0
CTRL
00: GPIO1/CD# is configured as a GPIO input
01: GPIO1/CD# is configured as a GPIO open drain output
10: GPIO1/CD# is configured as a GPIO push-pull output
11: Invalid, do not use
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Rev 1A