Traffic Lights!

If you are on this page then I'm assuming you have done the "Getting Your Brain (Arduino) to think" BLINK test and understand that SKETCH.

Now you will use your breadboard and Arduino to create a traffic light crossing.

STEPS:

1. Cut and paste the Traffic Light sketch into the IDE (Text below)
2. Breadboard the necessary circuit with LEDS on pins as indicated in the sketch.
3. Upload the sketch and see if it works
4. If the circuit works change the time parameters (delay command) to get the lights to work on different delays. This will help you understand how the program works!

TRAFFIC LIGHT SKETCH

/* This program mimics the operation of traffic lights.

It will teach you about creating more than one output on the Arduino.

Current limiting resistors must be used on the LEDs to keep current

below maximum for the LED and below 40mA limit of I/O of Arduino */

int greenled = 12; // green led pin number

int orangeled = 13; // orange led pin number

int redled = 14; // red led pin number

void setup()

{

pinMode(12, OUTPUT); //Pinmodes of the leds

pinMode(13, OUTPUT);

pinMode(14, OUTPUT);

}

void loop()

{

digitalWrite(redled, HIGH); //turns on red light

delay(5000); //waits 5000 ms (5 seconds)

digitalWrite(redled, LOW); //turns off red light

digitalWrite(greenled, HIGH); // turns on green light

delay(3000); //waits 3000ms (3 seconds)

digitalWrite(greenled, LOW); //turns off green light)

digitalWrite(orangeled, HIGH); // turns on orange light

delay(1000); // 2000 ms (2 seconds)

digitalWrite(orangeled, LOW); //orange light off

}

For this project we will now add a button switch. When this button is pressed the lights change to red allowing the pedestrian to cross.

/* This program will change the traffic light to red to allow Mr Woody to cross the road!*/

int red = 11;

int amber = 12;

int green = 13;

int button = 2;

void setup() {

pinMode (red, OUTPUT);

pinMode (amber, OUTPUT);

pinMode (green, OUTPUT);

pinMode (button, INPUT);

digitalWrite (green, HIGH); //start with green light ON

}

void loop () {

/*check for a push of the button*/

int state = digitalRead(button);

if (state == HIGH) {

changeLights(); // function to change lights

}

}

void changeLights () {

digitalWrite (green, LOW); //turn green light off

digitalWrite (amber, HIGH);//turn amber on

delay (2000); //amber on for 2 seconds

digitalWrite (amber , LOW); //switch amber off

digitalWrite (red, HIGH); // switch red light on

delay (6000);// red light on for 6 seconds

digitalWrite (red, LOW); //red off

digitalWrite (green, HIGH); //turn green back on

}

STEPS:

1. Cut and paste the Traffic Light sketch into the IDE (Text below)
2. Breadboard the necessary circuit with LEDS on pins as indicated in the sketch.
3. Upload the sketch and see if it works
4. If the circuit works change the time parameters (delay command) to get the lights to work on different delays. This will help you understand how the program works!