Debugging Klipper communication with a MCU is not trivial: Klipper has debug commands, but these commands use the same communication protocol that might need to be debugged.

My Klipper branch adds debug_print function that outputs text to the serial port for STM32G0B1 MCU.

The board I was debugging is BTT EBB36. It does not have a serial port header, so I had to reuse a couple of probe pins:

BTT EBB36 pinout