Arduino Nano - Traffic Light

This tutorial instructs you how to use an Arduino Nano to control a traffic light module. Specifically, we'll cover the following aspects:

Hardware Preparation

1×Arduino Nano
1×USB A to Mini-B USB cable
1×Traffic Light Module
1×Jumper Wires
1×(Optional) 9V Power Adapter for Arduino Nano
1×(Recommended) Screw Terminal Adapter for Arduino Nano

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Overview of Traffic Light Module

Pinout

A traffic light module comprises four pins:

  • GND pin: Connect this pin to the GND of Arduino Nano.
  • R pin: Controls the red light; connect this pin to a digital output of Arduino Nano.
  • Y pin: Manages the yellow light; connect this pin to a digital output of Arduino Nano.
  • G pin: Governs the green light; connect this pin to a digital output of Arduino Nano.
Traffic Light Pinout

How It Works

Wiring Diagram

The wiring diagram between Arduino Nano and traffic light

This image is created using Fritzing. Click to enlarge image

How To Program For Traffic Light module

  • Configure an Arduino Nano's pins to the digital output mode by using pinMode() function
pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT);
digitalWrite(PIN_RED, HIGH); // turn on RED digitalWrite(PIN_YELLOW, LOW); // digitalWrite(PIN_GREEN, LOW); delay(RED_TIME); // keep red led on during a period of time

Arduino Nano Code

/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-traffic-light */ #define PIN_RED 3 // The Arduino Nano pin connected to R pin of traffic light module #define PIN_YELLOW 4 // The Arduino Nano pin connected to Y pin of traffic light module #define PIN_GREEN 5 // The Arduino Nano pin connected to G pin of traffic light module #define RED_TIME 4000 // RED time in millisecond #define YELLOW_TIME 4000 // YELLOW time in millisecond #define GREEN_TIME 4000 // GREEN time in millisecond void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { // red light on digitalWrite(PIN_RED, HIGH); // turn on digitalWrite(PIN_YELLOW, LOW); // turn off digitalWrite(PIN_GREEN, LOW); // turn off delay(RED_TIME); // keep red light on during a period of time // yellow light on digitalWrite(PIN_RED, LOW); // turn off digitalWrite(PIN_YELLOW, HIGH); // turn on digitalWrite(PIN_GREEN, LOW); // turn off delay(YELLOW_TIME); // keep yellow light on during a period of time // green light on digitalWrite(PIN_RED, LOW); // turn off digitalWrite(PIN_YELLOW, LOW); // turn off digitalWrite(PIN_GREEN, HIGH); // turn on delay(GREEN_TIME); // keep green light on during a period of time }

Detailed Instructions

  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino Nano
  • Check out the traffic light module

It's important to note that the exact workings of a traffic light can vary depending on the specific design and technology used in different regions and intersections. The principles described above provide a general understanding of how traffic lights operate to manage traffic and enhance safety on the roads.

The code above demonstrates individual light control. Now, let's enhance the code for better optimization.

Arduino Nano Code Optimization

  • Let's improve the code by implementing a function for light control.
/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-traffic-light */ #define PIN_RED 3 // The Arduino Nano pin connected to R pin of traffic light module #define PIN_YELLOW 4 // The Arduino Nano pin connected to Y pin of traffic light module #define PIN_GREEN 5 // The Arduino Nano pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = { PIN_RED, PIN_YELLOW, PIN_GREEN }; const int times[] = { RED_TIME, YELLOW_TIME, GREEN_TIME }; void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { // red light on trafic_light_on(RED); delay(times[RED]); // keep red light on during a period of time // yellow light on trafic_light_on(YELLOW); delay(times[YELLOW]); // keep yellow light on during a period of time // green light on trafic_light_on(GREEN); delay(times[GREEN]); // keep green light on during a period of time } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }
  • Let's improve the code by using a for loop.
/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-traffic-light */ #define PIN_RED 3 // The Arduino Nano pin connected to R pin of traffic light module #define PIN_YELLOW 4 // The Arduino Nano pin connected to Y pin of traffic light module #define PIN_GREEN 5 // The Arduino Nano pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = {PIN_RED, PIN_YELLOW, PIN_GREEN}; const int times[] = {RED_TIME, YELLOW_TIME, GREEN_TIME}; void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { for (int light = RED; light <= GREEN; light ++) { trafic_light_on(light); delay(times[light]); // keep light on during a period of time } } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i ++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }
  • Let's improve the code by using millis() function intead of delay().
/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-traffic-light */ #define PIN_RED 3 // The Arduino Nano pin connected to R pin of traffic light module #define PIN_YELLOW 4 // The Arduino Nano pin connected to Y pin of traffic light module #define PIN_GREEN 5 // The Arduino Nano pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = { PIN_RED, PIN_YELLOW, PIN_GREEN }; const int times[] = { RED_TIME, YELLOW_TIME, GREEN_TIME }; unsigned long last_time = 0; int light = RED; // start with RED light void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); trafic_light_on(light); last_time = millis(); } // The loop function repeats indefinitely void loop() { if ((millis() - last_time) > times[light]) { light++; if (light >= 3) light = RED; // new circle trafic_light_on(light); last_time = millis(); } // TO DO: your other code } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }

Video Tutorial