Ultra96 Serial Console during Linux Boot

Question

I am trying to enable the serial console when Linux boots. I modified the dts file to add console=ttyPS1,115200 bootargs.

I still do not get any messages on the serial port.

I am using the Avnet USB-UART/JTAG Module for Ultra 96 which connects RX/TX on J6

What could be the issue ?

bhfletcher · Accepted Answer

Josh is correct. Both the out-of-box Linux image and the posted PetaLinux 2018.2 BSP connect PS UART1 via EMIO to pins G5 (Rx) and F6 (Tx), which are pinned out to the LS Mezzanine Connector pins 13 and 11. You would either need to plug in a Mezzanine that has an on-board USB-UART transceiver (like the Seeed studio sensor mezzanine) or use your own USB-UART transceiver connected to those pins. At the time these designs were created, the JTAG/UART pod didn't exist, so it was convenient for the developers to use the mezzanine.

We are working on changing this for the next version of the BSP that gets published so the PS UART1 output is pinned out to MIOs on J6.

Bryan