LED Helligkeitssensor - Arduino Uno mit 4 LEDs

int photocellPin = 0;
int photocellReading;
int rot = 13;
int gelb = 12;
int gruen = 11;
int gruener = 10;

void setup(void) {
  Serial.begin(9600);
  pinMode(rot, OUTPUT);
  pinMode(gelb, OUTPUT);
  pinMode(gruen, OUTPUT);
  pinMode(gruener, OUTPUT);
}

void loop(void) {
  photocellReading = analogRead(photocellPin);

  Serial.print("Analog reading = ");
  Serial.print(photocellReading);

  if (photocellReading < 20) {
    Serial.println(" - Dark");
    digitalWrite(rot, HIGH);
    digitalWrite(gelb, LOW);
    digitalWrite(gruen, LOW);
    digitalWrite(gruener, LOW);
  } else if (photocellReading < 200) {
    Serial.println(" - Dim");
    digitalWrite(rot, LOW);
    digitalWrite(gelb, HIGH);
    digitalWrite(gruen, LOW);
    digitalWrite(gruener, LOW);
  } else if (photocellReading < 500) {
    Serial.println(" - Light");
    digitalWrite(rot, LOW);
    digitalWrite(gelb, LOW);
    digitalWrite(gruen, HIGH);
    digitalWrite(gruener, LOW);
  } else if (photocellReading < 800) {
    Serial.println(" - Bright");
    Serial.println(" - Light");
    digitalWrite(rot, LOW);
    digitalWrite(gelb, LOW);
    digitalWrite(gruen, HIGH);
    digitalWrite(gruener, HIGH);
  } else {
    Serial.println(" - Very bright");
    Serial.println(" - Light");
    digitalWrite(rot, HIGH);
    digitalWrite(gelb, HIGH);
    digitalWrite(gruen, HIGH);
    digitalWrite(gruener, HIGH);
  }
  delay(2000);
}