STM32G0: USART flash and Serial Monitor via the same USART Interface or "How to use pin remap"

[olikraus]

I am very much impressed by STM32duino.

Just like a normal AVR UNO Board I can flash and communicate with the board via serial interface. Only a small little trick is required (see below). I didn't found that trick in the Wiki for this project, so this is why I created this discussion.

USB-USART converter is connected to PA9 (TX) and PA10 (RX).

Flashing works as expected (issue #1637 needs to be considered). But how does the serial monitor work? I figured out, that we need to assign and remap the pins with setRx and setTx command.
The important trick is this: Pin names need an appended "_R" because those pins need to be remapped first.

#define MYPIN 6

void setup() {
  Serial.setRx(PA_10_R);
  Serial.setTx(PA_9_R);
  Serial.begin(9600);
  pinMode(MYPIN, OUTPUT);
  Serial.println("setup done");
}

void loop() {
  Serial.println(millis());
  digitalWrite(MYPIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(300);                       // wait for a second
  digitalWrite(MYPIN, LOW);    // turn the LED off by making the voltage LOW
  delay(300);                       // wait for a second
}

Note that package pin 7 (PA_13) is mapped to Arduino digital pin 6.

[fpistm]

https://github.com/stm32duino/wiki/wiki/API#hardwareserial

[olikraus]

yes, but the mentoined wiki does not tell, that I have to remap PA_10 and PA_9, thats why I created this "show and tell" topic.

[fpistm]

So title should be: how to use remap pins of the STM32G0 😉

[olikraus]

Updated title :-)