SBC Axel SBC/Interfaces and Connectors/UARTs

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History
Version Issue Date Notes
1.0.0 Oct 2020 First DESK release


UARTs interface[edit | edit source]

Description[edit | edit source]

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

  • J25 is a 6x1x2.54 pitch vertical header for the UART4 port. This is a Digilent Pmod™ Compatible connector for the UART Pmod™ Compatiblemodule (6-Pin Pmod™ Compatible Connector Digilent Pmod™ Interface Specification Type 4 UART)


PMOD configuration


  • J21 is a standard DB9 male connector for the configurable UART5 port. The board provides some configuration options for the selection of the UART mode (RS232/RS422/RS485 with auto-direction)


DB9 configuration

Signals[edit | edit source]

The following tables describes the interface signals

UART4[edit | edit source]

Pin# SOM Pin# Pin name Pin function Pin Notes
1 J10.50 PMOD_A0 Clear to send
2 J10.89 PMOD_A1 Transmit data
3 J10.91 PMOD_A2 Receive data
4 J10.40 PMOD_A3 Request to send
5 - DGND Ground
6 - 3V3 +3.3 V

UART5[edit | edit source]

Pin# SOM Pin# Pin name RS-232 RS-422 RS-485
1 - Not connected Not connected Not connected Not connected
2 J10.95 UART5_A UART2 receive line UART5_A UART5_A
3 J10.93 UART5_Y UART2 transmit line UART5_Y UART5_A
4 - Not connected Not connected Not connected Not connected
5 - DGND Ground Ground Ground
6 - Not connected Not connected Not connected Not connected
7 J10.105 UART5_Z UART2 Request To Send UART5_Z UART5_B
8 J10.107 UART5_B UART2 Clear To Send UART5_B UART5_B
9 - Not connected Not connected Not connected Not connected

The J19 and J20 jumpers are used to configure the UART mode, as reported below:

Jumper RS232 mode RS422 mode RS485 mode
1-3 open open closed
5-7 open closed open
9-11 open closed open
2-4 open open closed
6-8 open closed closed
10-12 open closed closed
13-15 open open closed
14-16 open open closed
J19 and J20 connectors
UART5 jumper configuration


Device mapping[edit | edit source]

  • UART4 is mapped to /dev/ttymxc3 device in Linux
  • UART5 is mapped to /dev/ttymxc4 device in Linux

Device usage[edit | edit source]

  • UART4 can be used with a PMOD adapter or with a TTL peripheral
  • UART5 is a MultiProtocol that support (after harware Jumper configuration) the RS232, RS4222 or RS485 protocols. The related device tree file has to be properly configured too for enabling the GPIO transceiver configuration.