ZERO SOM/ZERO Evaluation Kit/Interfaces and Connectors/UARTs

History
Issue Date	Notes
2026/01/08	First documentation release

UARTs interface

Description

The UARTs interface available on the Evaluation Kit are mapped to the following connectors:

• J45 is a standard DB9 male connector for the RS232 UART port

UART_A

• J44 is a 6x1x2.54mm female vertical socket header for the UART_D port. This is a Digilent Pmod™ Compatible connector for the UART Pmod™ Compatiblemodule (6-Pin Pmod™ Compatible Connector Digilent Pmod™ Interface Specification Type-3 UART)

UART_D Pmod Type-3

• J43 is a 6x1x2.54mm female vertical socket header for the OSM-L UART_C port. This port is not available in the ZERO SOM

Signals

The following tables describes the interface signals

UART_A

Pin#	OSM ball	Pin name	RS-232
1	-	Not connected	Not connected
2	B_A13	UART_A_RX	UART_A receive line
3	B_B13	UART_A_TX	UART_A transmit line
4	-	Not connected	Not connected
5	-	DGND	Ground
6	-	Not connected	Not connected
7	B_C13	UART_A_RTS	UART_A Request To Send
8	B_C14	UART_A_CTS	UART_A Clear To Send
9	-	Not connected	Not connected

UART_D

Pin#	OSM ball	Pin name	Pin function	Pin Notes
1	-	-	-
2	B_C23	PMOD_A1	Transmit data
3	B_C22	PMOD_A2	Receive data
4	-	-	-
5	-	DGND	Ground
6	-	1V8	+1.8 V

Device mapping

• UART_A is mapped to /dev/ttySC3 device in Linux
• UART_D is mapped to /dev/ttySC5 device in Linux

Device usage

• UART_A supports the RS232 protocol
• UART_D can be used with a PMOD Type-3 adapter or with a LVTTL peripheral