Example Code for Arduino-Traffic Light

Wiring Diagram

Sample Code

/*
   Traffic Light
   This code copied from the book Beginning-Arduino.
*/
int carRed = 12; //assign the car lights
int carYellow = 11;
int carGreen = 10;
int button = 9; //button pin
int pedRed = 8; //assign the pedestrian lights
int pedGreen = 7;
int crossTime =5000; //time for pedestrian to cross
unsigned long changeTime;//time since button pressed

void setup() {
    pinMode(carRed, OUTPUT);
    pinMode(carYellow, OUTPUT);
    pinMode(carGreen, OUTPUT);
    pinMode(pedRed, OUTPUT);
    pinMode(pedGreen, OUTPUT);
    pinMode(button, INPUT);
    digitalWrite(carGreen, HIGH); //turn on the green lights
    digitalWrite(pedRed, HIGH);
}

void loop() {
    int state = digitalRead(button);
        //check if button is pressed and it is over 5 seconds since last button press
        if(state == HIGH && (millis() - changeTime)> 5000){
               //call the function to change the lights
               changeLights();
        }
}

void changeLights() {
    digitalWrite(carGreen, LOW); //green off
    digitalWrite(carYellow, HIGH); //yellow on
    delay(2000); //wait 2 seconds

    digitalWrite(carYellow, LOW); //yellow off
    digitalWrite(carRed, HIGH); //red on
        delay(1000); //wait 1 second till its safe

    digitalWrite(pedRed, LOW); //ped red off
    digitalWrite(pedGreen, HIGH); //ped green on

    delay(crossTime); //wait for preset time period

    //flash the ped green
        for (int x=0; x<10; x++) {
            digitalWrite(pedGreen, HIGH);
        delay(250);
        digitalWrite(pedGreen, LOW);
        delay(250);
         }

        digitalWrite(pedRed, HIGH);//turn ped red on
    delay(500);

    digitalWrite(carRed, LOW); //red off
    digitalWrite(carYellow, HIGH); //yellow on
    delay(1000);
    digitalWrite(carYellow, LOW); //yellow off
        digitalWrite(carGreen, HIGH);

    changeTime = millis(); //record the time since last change of lights
    //then return to the main program loop
}