AXEL Lite SOM/AXEL Lite Evaluation Kit/Interfaces and Connectors/UARTs

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Version Issue Date Notes


Oct 2020 First DESK release
1.0.1 Apr 2022 Add GPIO setting reference

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 6x1x2.54mm horizontal socket 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 UART5 receive line UART5_A UART5_A
3 J10.93 UART5_Y UART5 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 UART5 Request To Send UART5_Z UART5_B
8 J10.107 UART5_B UART5 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, see Configuring the RS232/RS485 mode