const int startPin = 2;
const int endPin = 5;
int currentPin = startPin;
bool ascending = true; // Richtungsflag

void setup() {
  for (int i = startPin; i <= endPin; i++) {
    pinMode(i, OUTPUT);
  }
}

void loop() {
  static unsigned long previousMillis = 0;
  const long interval = 1000; // Intervall (Vergessen wie Lange)

  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;

    for (int i = startPin; i <= endPin; i++) {
      digitalWrite(i, LOW);
    }
    
    digitalWrite(currentPin, HIGH); 

    if (ascending) {
      if (currentPin < endPin) {
        currentPin++;
      } else {
        ascending = false; // Richtung wechseln
        currentPin = endPin - 1;
      }
    } else {
      if (currentPin > startPin) {
        currentPin--;
      } else {
        ascending = true; // Zurück zur anderen Richtung
        currentPin = startPin + 1;
      }
    }
  }
}