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Lesson 29: Traffic Light Module

In this lesson, you will learn how to use Arduino to control a mini LED traffic light. We’ll cover programming the Arduino Uno to cycle through green, yellow, and red lights, simulating a real traffic signal. This project is ideal for beginners as it provides practical experience in coding light sequences and timing controls on the Arduino platform.

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Universal Maker Sensor Kit	94	Universal Maker Sensor Kit

You can also buy them separately from the links below.

Component Introduction	Purchase Link
Arduino UNO R3 or R4	BUY
Traffic Light Module	BUY

• Arduino UNO R3 or R4

• Traffic Light Module

Wiring

Code

Code Analysis

1. Before any operations, we define constants for the pins where LEDs are connected. This makes our code easier to read and modify.

const int rledPin = 9;  //red
const int yledPin = 8;  //yellow
const int gledPin = 7;  //green

2. Here, we specify the pin modes for our LED pins. They are all set to OUTPUT because we intend to send voltage to them.

void setup() {
  pinMode(rledPin, OUTPUT);
  pinMode(yledPin, OUTPUT);
  pinMode(gledPin, OUTPUT);
}

3. This is where our traffic light cycle logic is implemented. The sequence of operations is:

   • Turn the green LED on for 5 seconds.

   • Blink the yellow LED three times (each blink lasts for 0.5 seconds).

   • Turn the red LED on for 5 seconds.

void loop() {
  digitalWrite(gledPin, HIGH);
  delay(5000);
  digitalWrite(gledPin, LOW);

  digitalWrite(yledPin, HIGH);
  delay(500);
  digitalWrite(yledPin, LOW);
  delay(500);
  digitalWrite(yledPin, HIGH);
  delay(500);
  digitalWrite(yledPin, LOW);
  delay(500);
  digitalWrite(yledPin, HIGH);
  delay(500);
  digitalWrite(yledPin, LOW);
  delay(500);

  digitalWrite(rledPin, HIGH);
  delay(5000);
  digitalWrite(rledPin, LOW);
}