JoJoPi has a point - by default, CM5 (like Pi 5) puts the UART on the debug header, and that is what /dev/serial0 maps to. However, there are two ways to enable UART0 on GPIOs 14 & 15:
1. Add "dtparam=uart0" to config.txt. To also make it the new /dev/serial0, use "dtparam=uart0_console" instead. As before, you'll probably want to ensure that cmdline.txt doesn't include "console=serial0,.." or "console=ttyAMA0,...".
2. With the very latest EEPROM image (pieeprom-2024-12-07), "enable_uart=1" in config.txt will force "dtparam=uart0_console" unless you have a serial cable plugged into the debug header, in which case it uses that instead (the firmware looks for something pulling up the RX pin).
1. Add "dtparam=uart0" to config.txt. To also make it the new /dev/serial0, use "dtparam=uart0_console" instead. As before, you'll probably want to ensure that cmdline.txt doesn't include "console=serial0,.." or "console=ttyAMA0,...".
2. With the very latest EEPROM image (pieeprom-2024-12-07), "enable_uart=1" in config.txt will force "dtparam=uart0_console" unless you have a serial cable plugged into the debug header, in which case it uses that instead (the firmware looks for something pulling up the RX pin).
Statistics: Posted by PhilE — Mon Dec 09, 2024 5:41 pm