// eine Ampelschaltung
int led_rot   = 12;  // LED rot
int led_gelb  = 11;  // LED gelb
int led_gruen = 10;  // LED grün

void setup() {
  // put your setup code here, to run once:
  pinMode(led_rot, OUTPUT);
  pinMode(led_gelb, OUTPUT);
  pinMode(led_gruen, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  // Rot
  digitalWrite(led_rot, HIGH);
  digitalWrite(led_gelb, LOW);
  digitalWrite(led_gruen, LOW);
  delay(3000);
  // Rot-Gelb
  digitalWrite(led_gelb, HIGH);
  delay(1000);
  // Grün
  digitalWrite(led_rot, LOW);
  digitalWrite(led_gelb, LOW);
  digitalWrite(led_gruen, HIGH);
  delay(2500);
  // Gelb
  digitalWrite(led_gelb, HIGH);
  digitalWrite(led_gruen, LOW);
  delay(1500);
}