Arduino Project

Traffic light

Course Introduction

In this lesson, you’ll learn how to build a simple traffic light system using the Arduino UNO R4, 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 Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN

COMPONENT INTRODUCTION

QUANTITY

PURCHASE LINK

1

Arduino UNO R4 Minima/Arduino UNO R4 WIFI

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

9.webp__PID:a39b4864-1ba9-4812-ad8b-ca088f594168

Common Connections:

Traffic light LED
R: Connect to 10 on the Arduino.
Y: Connect to 11 on the Arduino.
G: Connect to 12 on the Arduino.
GND: Connect to breadboard’s negative power bus.

4-Digit Segment Display Module
CLK: Connect to 3 on the Arduino.
DIO: Connect to 2 on the Arduino.
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 Adafruit SSD1306 and TM1637Display and install it.
Don’t forget to select the board(Arduino UNO R4 Minima/WIFI) and the correct port before clicking the Upload button.


#include 

// TM1637 pin definitions
#define CLK 3
#define DIO 2

// Traffic light pins
const int redPin = 10;
const int yellowPin = 11;
const int greenPin = 12;

// Create display object
TM1637Display display(CLK, DIO);

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

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

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--) {
    display.showNumberDec(i, true, 2, 2); // Display in rightmost 2 digits
    delay(1000);
  }
  display.clear();
}