I do not know how this is supposed to work on CM5; it is not currently mentioned in the documentation or the documentation. But on a Pi5, /dev/serial0 points to ttyAMA10, which is the one on the dedicated JST header. If you enable a UART in the traditional place of GPIO14/15 (dtoverlay=uart0-pi5) it does not get an alias, so you have to open it as ttyAMA0.Barring a natural disaster, it's guaranteed to point to the non-Bluetooth UART - provided udev has had a chance to run (see @rolivers comment).
In other words, the old rule that serial0 is the primary UART is only true if you mean the one that you would use as a console, not the one you would use to talk to an MCU. And there is actually no way it could be true for both.
Statistics: Posted by jojopi — Mon Dec 09, 2024 4:36 pm