Traffic Signal / Stop Light Wiring with Arduino Controller

I always wanted an old traffic signal and finally got one recently.  However, it was very simply wired so that all the lights were fixed on.  What fun is that?  I also wanted to try out an Arduino controller and thought this would be a nice simple project to incorporate it into.

This Instructable will show you how to wire up an old traffic signal with an Arduino controller to function like a real traffic light.  I used a pretty simple program and controls.  Given the power of the Arduino controller, there are a lot of ways you can customize this.

Step 2: The plan

Below is a wiring diagram for the traffic signal.  Hopefully this is pretty clear what gets wired to what.

Above is a photo of the Arduino Uno and the relay module with the wiring between the two attached.  I only had male to male jumpers, so I used a Molex connector and my mad soldering skills to make a connector (second photo).  It is probably easier to use male to female jumpers to connect everything or find a 6 pin jumper to use.  The Arduino has all female sockets and the relay module has all male pins.

If you have not used an Arduino before, see this Instructable by randofo: http://www.instructables.com/id/Intro-to-Arduino/

Download and start the Arduino programming software if you have not already.  Connect the Arduino to your computer with a USB B cable.

Copy and paste the code the below and upload it to the Arduino.  One the code uploads it should start running immediately on the Arduino.  You should see the indicator lights going on and off on the relay unit and hear the relay switches tripping.

You can make this more simple or complicated if you want.  I have it set up to cycle through 25 normal cycles, switch to blinking red for a few minutes, do 25 more normal cycles, switch to blinking yellow for a few minutes, and then repeat.

//Fzumrk’s traffic controller code

// name your pins:
int red = 12;
int yellow = 11;
int green = 10;

// the setup routine runs once when you press reset:
void setup() {
// initialize the digital pin as an output.
pinMode(red, OUTPUT);
pinMode(yellow, OUTPUT);
pinMode(green, OUTPUT);
}
int  var = 0; //defines and sets initial value for variables used below
int var1 = 0; //defines and sets initial value for variables used below

// the loop routine runs over and over again forever:
void loop() {

// sets initial value for pins so that lights start as “off”
digitalWrite(green, HIGH);
digitalWrite(yellow, HIGH);
digitalWrite(red, HIGH);

while(var < 25){
// repeats normal cycle 25 times
digitalWrite(green, LOW);   // turns the green light on
delay(20000);               // holds the green light on for 20 seconds
digitalWrite(green, HIGH);    // turns the green light off
delay(600);               // slight pause between lights
digitalWrite(yellow, LOW);  //turns the yellow light on
delay(4000); //holds the yellow light for 4 seconds (watch out for that red-light camera!)
digitalWrite(yellow, HIGH); //turns the yellow light off
delay(600);  //slight pause between lights
digitalWrite(red, LOW);  //turns the red light on
delay(20000);  //holds the red light on for 20 seconds
digitalWrite(red, HIGH);  //turns the red light off
delay(600);  //slight pause between lights
var++;}  //adds 1 to variable “var” for repeat count

// after 25 cycles above, the light switches to “power outage mode”, flashing red
delay(600); //slight delay
var1=0; //resets variable “var1” to 0
while(var1 < 120) {
// repeats power outage cycle 120 times – 2 minutes
digitalWrite(red, LOW);
delay(600);
digitalWrite(red, HIGH);
delay(400);
var1++;}
var = 0;

//switches back to normal cycle after “power outage” cycle is done
while(var < 25){
// back to normal light cycle for 25 cycles
digitalWrite(green, LOW);   // turn the LED on (HIGH is the voltage level)
delay(20000);               // wait for a second
digitalWrite(green, HIGH);    // turn the LED off by making the voltage LOW
delay(600);               // wait for a second
digitalWrite(yellow, LOW);
delay(4000);
digitalWrite(yellow, HIGH);
delay(600);
digitalWrite(red, LOW);
delay(20000);
digitalWrite(red, HIGH);
delay(600);
var++;}
delay(600);

//switches to “late night cycle” flashing yellow for 2 minutes, similar to flashing red above
var1=0;
while(var1 < 120) {
digitalWrite(yellow, LOW);
delay(600);
digitalWrite(yellow, HIGH);
delay(400);
var1++;}
var = 0;
//goes back to normal cycle at top and repeats forever
}

For more detail: Traffic Signal Wiring with Arduino Controller