I would like to start a few debug commands via the console. To do this I have to read the first serial port and not block the program.

The following command does not block, but nothing is read in and the error message "Multiple decode errors occurred: Try checking the baud rate and XTAL frequency setting in menuconfig" appears.

setvbuf(stdin, NULL, _IONBF, 0);
c = fgetc(stdin);

I use ESP-IDF 5.1 and the the "M5Dial-UserDemo" as base.