Port UART updates to rp235x-hal

[jannic]

The updates from #798, #837 and #838 were only applied to rp2040-hal. This patch ports them to rp235x-hal.

[thejpster]

What testing has been done? Should I run a demo and try it?

[jannic]

Only tested that it still builds. It seems like we don't have on-target tests for UART yet.
I'd consider the port to rp235x relatively low-risk as the changes don't touch any low-level details. But of course, doing some actual testing would be very welcome!

[thejpster]

I think we should write a loop back test that sends bytes with good and bad parity, just to check this is working as expected.

[thejpster]

I wrote a UART loopback program, and fixed some issues I observed: 1f6251a

You can cherry-pick that here if you like it.

[jannic]

I wrote a UART loopback program, and fixed some issues I observed: 1f6251a

You can cherry-pick that here if you like it.

Thanks!
Did you use external pull-ups? The uart_loopback example didn't work for me. Took me a while to find out what's going on because without defmt I didn't see the unwrap failing. The fix was enabling the internal pull-ups on the RX pins.
(Only tested on rp2040 yet)

[thejpster]

No I didn't. Just a DuPont wire on a Pimoroni Pico 2 Plus.

[jannic]

Interesting. I reproducibly got a break error on rp2040 before I activated the pull-ups.

[thejpster]

🤷