🪲Bug: Ibus not working with inverted RX on RP2040 Microcontroller

[gandy92]

Describe the bug
Using the ibus receiver class with an inverted line connected to a RP2040 mcu only yields 0 for all channels. The reason being that the ibus.setup() routine has architecture dependent code which does not honor the ibus._inverted flag.

A valid workaround is to add the inverting calls to the main sketch:

ibus receiver(&Serial1, SBUS_RX_PIN, SBUS_TX_PIN, true);  // RP2040 requires a TX_PIN so to not hang up the mcu
void setup()
{
  Serial1.setInvertRX(true);
  Serial1.setInvertTX(true);
  receiver.begin();

To Reproduce
I can try to provide an example sketch that demonstrates using the ibus protocol with the rp2040, if this is required.

Additional context
The problematic code can be seen in this line:

SerialIO/src/ibus/ibus.cpp

Line 18 in b97e68f

serialPort->begin(IBUS_BAUDRATE, SERIAL_8N1);

The issue is resolved by adding two lines with calls to serialPort->setInvertRC() and serialPort->setInvertTX() before serialPort->begin(), changing the code to:

#elif defined(ARDUINO_ARCH_RP2040)
  SerialUART *serialPort = (SerialUART *)_rxPort;
  serialPort->setPinout(_txPin, _rxPin);
  serialPort->setInvertRX(_inverted);
  serialPort->setInvertTX(_inverted);
  serialPort->begin(IBUS_BAUDRATE, SERIAL_8N1);
#else

[Witty-Wizard]

@gandy92, Thank your bringing this to my notice.
I didn't knew the RP2040 Microcontroller supported UART inversion, I have made these changes in the #27 PR, please try the new branch and share the results so that I can merge the code into the main branch

[gandy92]

@Witty-Wizard thank you for your prompt reaction. Now that you mention it, I'm not using the vanilla RP2040 arduino framework but the work from https://github.com/earlephilhower/arduino-pico which adds a ton more features. I'll try to check if the pin inversion is also available in the vanilla code or is part of these additional features.

[gandy92]

@Witty-Wizard I ran a quick check and as it turns out, I can not compile SerialIO with the vanilla raspberrypi platform, where SerialUART seems to be unknown. So maybe the RP2040-related code already relies on the earlephilhower core? If so, may I suggest adding it to the documentation somewhere?
If you like, I can try to create a minimal sketch showing how to set up ibus with therp2040 to be included with the examples? Would you prefer a PR for that or should I just paste the code here?

[Witty-Wizard]

Sure it would be great if u could create an example sketch, and add doxygen style comments to it, then it will be automatically included in the documentation.

[gandy92]

Ok, I'll check out the other examples to adhere to the same scheme