XR21B1424_17 Datasheet, PDF (8/64 Pages) Exar Corporation – Enhanced 4-Ch Full-Speed USB UART

XR21B1424
Pin No.
Pin Name
56
GPIOD3/DTRD#
57
GPIOD2/DSRD#
58
GPIOD1/CDD#
59
GPIOD0/RID#/RWKD#
60
GPIOA9/RXTA
61
GPIOA8/TXTA
62
GPIOA7/RS485A
63
GPIOA6/CLKA
64
TXA
Type
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
O
Description
General purpose I/O, or UART Data-Terminal-Ready push-pull output (active low). Defaults to
GPIO input with internal pull-up resistor. See “Automatic DTR/DSR Hardware Flow Control” on
page 17.
General purpose I/O, or UART Data-Set-Ready input (active low). Defaults to GPIO input with
internal pull-up resistor. See “Automatic DTR/DSR Hardware Flow Control” on page 17.
General purpose I/O, or UART Carrier-Detect input (active low). Defaults to GPIO input with
internal pull-up resistor.
General purpose I/O, or UART Ring-Indicator input (active low), or Remote Wakeup input.
Defaults to GPIO input with internal pull-up resistor. Wakeup signaling to the USB host is sent
when a falling edge is detected. See “Remote Wakeup” on page 10.
General purpose I/O, or UART receive data indicator. Defaults to GPIO input with internal pull-
up resistor. See “TXT and RXT Pins” on page 19. When configured as receive indicator, this
pin will toggle at ~10Hz intervals while the UART is receiving data.
General purpose I/O, or UART transmit data indicator. Defaults to GPIO input with internal pull-
up resistor. See “TXT and RXT Pins” on page 19. When configured as transmit indicator, this
pin will toggle at ~10Hz intervals while the UART is transmitting data.
General purpose I/O, or auto RS-485 half-duplex control. Defaults to GPIO input with internal
pull-up resistor. See “Multidrop mode with address matching” on page 18.
General purpose I/O, or clock or pulse output. Defaults to GPIO input with internal pull-up
resistor. See “Programmable Output Clock” on page 16.
UART Transmit Data.
Type: I = Input, O = Output, I/O = Input/Output, PWR = Power, OD = Open-Drain
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