How to run the Arty A7 UART test by hand

You have an Arty A7 on its Raspberry Pi and want to run the UART test by hand.

The UART reaches the Pi through channel B of the FTDI chip, as /dev/ttyUSB1 at 115200 baud with no flow control. The test passes when the LiteX BIOS banner arrives and printable ASCII echoes back.

This procedure is waiting for its run: test-designs issue #248.

What you need

Steps

  1. On the Raspberry Pi, install the debug tool, fpgas-arty-debug.

    $ sudo apt install fpgas-online-arty-debug

  2. On the Raspberry Pi, run the test, which loads the UART design and runs its host script.

    $ sudo fpgas-arty-debug test uart

Check

  • The test passes when its host script exits 0, so echo $? prints 0.

If it fails

What you see

Likely cause

Fix

no /dev/ttyUSB1

the Arty’s FTDI is not on USB; a board in that state cannot be programmed or reached on its console

run lsusb. If it does not list the FT2232H, 0403:6010, check the USB cable between the board and the Pi

the test talks to the wrong device

the tool uses /dev/ttyUSB1, and another USB serial device on the Pi has taken that name

find the UART channel’s own port: in ls -l /dev/serial/by-id/, the Arty’s entry ending in -if01-port0 points at it. Name that entry before test: sudo fpgas-arty-debug --port /dev/serial/by-id/<the -if01-port0 entry> test uart

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