Traffic Light Controller - Experimenting with Arduino

ardExp-trafficLight.ino

  /* Arduino Experimenter Challenge: Broken Traffic Light
   * This traffic light is -sooo close- to being correct, but something seems 
   * off with the logic...
   * 
   * Can you fix it? 
   * 
   * Hint: Think about how a functioning traffic light works and build out the logic-
   *  what steps should the lights go in?
   *  should two colors ever be on at the same time?
   * 
   * Going Further:
   *  after you get the light working correctly, invent your own traffic light system!
   *  
   *  
   */
  
  // global variables go here. set and change the led pin variables to match what you need
  int red = 13;
  int yellow = 12;
  int green = 8;

void setup() {
  // make sure to set the pinMode to output for EACH led variable
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  
}

void loop() {
  changeLights();
  delay(10000); //process starts over every 10 seconds
}

void changeLights() {
  //first, green is on and the other two are off:
  digitalWrite(red,HIGH);
  digitalWrite(yellow,LOW);
  digitalWrite(green,LOW);
  delay(5000); //red light for 5 seconds!

  //now, yellow light:
  digitalWrite(yellow,HIGH);
  digitalWrite(green,LOW);
  digitalWrite(red,LOW);
  delay(2000); //yellow light for 2 seconds!

  //now, green light:
  digitalWrite(green,HIGH);
  digitalWrite(red,LOW);
  digitalWrite(yellow,LOW);
  //green light!
 
}