Hello @michelman ,
By default USB to Serial is not enabled in the linux kernel of the Starter Package.
If you want to use a FTDI cable to have USB-A on the 157D-DK1 board and the serial part on another board, you have to use the developer package.
You have to follow the Getting Started "Develop on Arm® Cortex®-A7": https://wiki.st.com/stm32mpu/wiki/Getting_started/STM32MP1_boards/STM32MP157x-DK2/Develop_on_Arm%C2%AE_Cortex%C2%AE-A7
Install the SDK and get the developer package. Once you have the developer package on your machine, you can follow this wiki page that explains how to modify the linux configuration when using the developer package:
https://wiki.st.com/stm32mpu/wiki/Menuconfig_or_how_to_configure_kernel#Menuconfig_and_Developer_Package
and enable:
CONFIG_USB_SERIAL=y
# CONFIG_USB_SERIAL_CONSOLE is not set
CONFIG_USB_SERIAL_GENERIC=y
CONFIG_USB_SERIAL_SIMPLE=m
CONFIG_USB_SERIAL_FTDI_SIO=m
With these CONFIG enabled and once you have re-build your linux, you should be able to use your FTDI cable.
You should see these kind of traces in your Linux Boot Log:
[ 22.614405] usbserial: USB Serial support registered for FTDI USB Serial Device
[ 22.620589] ftdi_sio 2-1.2:1.0: FTDI USB Serial Device converter detected
[ 22.669315] usb 2-1.2: FTDI USB Serial Device converter now attached to ttyUSB0
Hope it helps,
Best Regards,
Kevin