XR21B1424 Datasheet, PDF (32/61 Pages) Exar Corporation – Enhanced 4-Ch Full-Speed USB UART

Bit
9:8
7
6:0
Default
0
Pin Open Drain on GPIO[9:8]
0: Pin configured as output is push-pull output
1: Pin configured as output is open drain output
1
Pin Open Drain on GPIO7/RS485
0: Pin configured as output is push-pull output
1: Pin configured as output is open drain output
0
Pin Open Drain on GPIO[6:0]
0: Pin configured as output is push-pull output
1: Pin configured as output is open drain output
Description
XR21B1424
PIN_PULLUP_EN (0x014) - Read/Write
This register controls all pins configured as inputs irrespective of if they are configured as GPIO or alternate functions.
Bit
15:11
10
9:0
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
1
RX
0: Disable pull-up on the RX pin
1: Enable pull-up on the RX pin. If both pull-up and pull-down resistors are selected, only the pull-up will be enabled.
1
Pin Pull-up Enable on GPIO[9:0]
0: Disable pull-up on the corresponding input pin
1: Enable pull-up on the corresponding input pin. If both pull-up and pull-down resistors are selected for a given GPIO, only
the pull-up will be enabled.
PIN_PULLDOWN_EN (0x015) - Read/Write
This register controls all pins configured as inputs irrespective of if they are configured as GPIO or alternate functions.
Bit
15:11
10
9:0
Default
Description
0
Reserved
These bits are reserved and should be written as ‘0’.
0
RX
0: Disable pull-down on the RX pin
1: Enable pull-down on the RX pin. If both pull-up and pull-down resistors are selected, only the pull-up will be enabled.
0
Pin Pull-down Enable on GPIO[9:0]
0: Disable pull-down on the corresponding input pin
1: Enable pull-down on the corresponding input pin. If both pull-up and pull-down resistors are selected for a given GPIO, only
the pull-up will be enabled.
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