The TOBY-L4 exposes multiple TTY ports, but each of them has different
purposes:
The TTY at interface #2 is a fully capable AT port but shouldn't be
used to start connections, so we flag it as secondary.
The TTY at interface #4 is a non-AT debug port, so we explicitly
ignore it to make probing faster.
The TTY at interface #6 is the fully capable AT port that must be used
as primary port.
The TTY at interface #8 is an AT-capable port but dedicated to FOTA
update operations.
Aleksander Morgado
ce203a1f74