//-------------------------------------------------------------------
void setup() {
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(8, OUTPUT);
}

//-------------------------------------------------------------------
void loop() {
  // rot
  digitalWrite(13, HIGH);
  digitalWrite(12, LOW);
  digitalWrite(8, LOW);
  delay(500);

  // gelb
  digitalWrite(13, LOW);
  digitalWrite(12, HIGH);
  digitalWrite(8, LOW);
  delay(500);

  // grün
  digitalWrite(13, LOW);
  digitalWrite(12, LOW);
  digitalWrite(8, HIGH);
  delay(500);
}