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Lesson 29: Traffic Light Module

In this lesson, you’ll learn how to use an ESP32 Development Board to control a Mini Traffic Light Module. We’ll cover setting up the board and writing code to create a traffic light sequence: 5 seconds of green light, blinking yellow light for 1.5 seconds, and 5 seconds of red light. This project is ideal for beginners in electronics and programming as it provides practical experience with output operations and basic timing control using the ESP32.

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
ESP32 & Development Board (ESP32 Board)	BUY
Traffic Light Module	BUY
Breadboard	BUY

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 = 25;  //red
const int yledPin = 26;  //yellow
const int gledPin = 27;  //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);
}