void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Hello, STM32!");
  pinMode(PA3, OUTPUT);
}

void loop() {
  Serial.println("TACK");
  digitalWrite(PA3, HIGH);
  delay(500); // this speeds up the simulation
  digitalWrite(PA3, LOW);
  delay(500); 
}