Traffic light

Note

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Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

Name	Includes ESP32 board	PURCHASE LINK
ESP32 Ultimate Starter Kit	ESP32 WROOM 32E +	BUY
Universal Maker Sensor Kit		BUY

Course Introduction

In this lesson, you’ll learn how to build a simple traffic light system using the ESP32, a TM1637 4-digit display, and LED.

The display counts down each light phase—red, yellow, and green—just like a real traffic signal.

Note

If this is your first time working with an ESP32 project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	ESP-WROOM-32 ESP32 ESP-32S Development Board	1	BUY
2	USB Type-C cable	1
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	4-Digit Segment Display Module	1	BUY
6	Traffic Light LED	1	BUY

Wiring

Common Connections:

Traffic light LED
- R: Connect to GPIO25 on the ESP32.
- Y: Connect to GPIO26 on the ESP32.
- G: Connect to GPIO27 on the ESP32.
- GND: Connect to breadboard’s negative power bus.
4-Digit Segment Display Module
- CLK: Connect to GPIO23 on the ESP32.
- DIO: Connect to GPIO22 on the ESP32.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.

Writing the Code

Note

You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for TM1637Display and install it.
Don’t forget to select the board(ESP32 Dev module) and the correct port before clicking the Upload button.

#include <TM1637Display.h>

// ------- TM1637 pins (ESP32 GPIOs) -------
#define CLK_PIN 23   // TM1637 CLK -> GPIO23
#define DIO_PIN 22   // TM1637 DIO -> GPIO22

// ------- Traffic light pins (ESP32 GPIOs) -------
const int redPin    = 25;  // Red LED
const int yellowPin = 26;  // Yellow LED
const int greenPin  = 27;  // Green LED

// Create display object
TM1637Display display(CLK_PIN, DIO_PIN);

void setup() {
  // Setup traffic light pins
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);

  // Initialize display
  display.setBrightness(7);  // 0 (dim) to 7 (bright)
  display.clear();
}

void loop() {
  // Red light phase - 10s
  digitalWrite(redPin, HIGH);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, LOW);
  countdown(10);

  // Yellow light phase - 3s
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, HIGH);
  digitalWrite(greenPin, LOW);
  countdown(3);

  // Green light phase - 10s
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, HIGH);
  countdown(10);
}

// Countdown function using TM1637 display
void countdown(int seconds) {
  for (int i = seconds; i > 0; i--) {
    // Show in rightmost 2 digits (positions 2 & 3)
    display.showNumberDec(i, true, 2, 2);
    delay(1000);
  }
  display.clear();
}