feat(uart): support UART Tx, Rx and Data invert function

[ndoo]

Fixes:
See also: #1418

Summary

This enables UART Tx, Rx and data invert function on STM32 families that support it.

In order to enable Tx, Rx and/or data invert, call respectively:

Serial1.setTxInvert();
Serial1.setRxInvert();
Serial1.setDataInvert();

This PR fixes/implements the following bugs/features

• Feature Support for UART RX/TX level inversion on F3/F7 platforms #1160
• Feature Support U[S]ART Inversion on STM32U0 #2669
• See also [U(S)ART] request list #1418

This adds a feature exposed by the native STM32 HAL & (some) hardware.

Validation

• Ensure CI build is passed.
• Tested a sketch with following lines of code:

  HardwareSerial sdiSerial = HardwareSerial(PA2);
  sdiSerial.setTxInvert();
  sdiSerial.begin(1200, SERIAL_7E1);
  

Closing issues

Closes #1160 #2669

[ndoo]

Workflow run status on my fork: https://github.com/ndoo/Arduino_Core_STM32/actions?query=branch%3Auart-invert

[ndoo]

Not sure if it actually works, marking as Draft again.

Squashed in a fixup for missing

    huart->AdvancedInit.RxPinLevelInvert = UART_ADVFEATURE_RXINV_ENABLE;
    huart->AdvancedInit.TxPinLevelInvert = UART_ADVFEATURE_TXINV_ENABLE;

[ndoo]

Please let me know if the code flow makes sense in uart.c. Thank you.

[fpistm]

Hi @ndoo
Thanks for the PR.
Will review it soon.

[fpistm]

Hi @ndoo
Thanks for this PR (well made 😉)
Some comments to address (open to discussion).
In addition, it would be fine to add new methods in the keywords.txt.
Could you also write doc about its usage to be added in the Wiki ?

[ndoo]

Thanks for the review. Since I seem to be headed in the right direction, I will extend this to invert data as well, for completeness.

FWIW, I had my sketch freeze trying to read from serial, but let me debug over SWD after everything is done.

[ndoo]

Force-pushed with the requested code changes. Workflows are still running.

I have to go to bed, but I will take a look at keywords.txt (which?) and updating the Wiki tomorrow.

[ndoo]

Done updating keywords.txt - now having a look at writing for the Wiki.

[ndoo]

Wiki PR: stm32duino/wiki_contrib#2

Taking PR out of draft. Do let me know if anything was missed. Cheers!

[fpistm]

Thanks @ndoo