I got my Wombats so hopefully I can play with them tomorrow. One other thing you could try if you really want to use the J14 uart and don’t need a console there…
First, make sure there’s no console started on ttyTCU0. If there is one started, do a
pgrep -fa getty and see which port it’s actually on. It could be ttyTCU0 or ttyS0. Whichever it is, do a
systemctl mask serial-getty@ttyTCU0 or
systemctl mask serial-getty@ttyS0 so systemd doesn’t try to start a console on that port on next boot.
That doesn’t prevent all the bootloader and kernel messages from dumping to that port so if your GPS has an “enable” pin tie that to a GPIO so that you can have a script that enables and disables the GPS after bootup. This way neither the GPS nor the bootloader will be confused by activity on the TCU port. Another option if don’t want to actually enable/disable the GPS is to use a simple 2 channel level shifter between the TCU port and the GPS and tie the level shifter’s enable pin to a GPIO. This will leave the GPS running but just cut off communication to the TCU port until you’re ready to use it.