Traffic Light System

Project Overview

This project builds on the blinking LED concept by introducing multiple outputs and sequential control. You will simulate a real-world traffic light system using three LEDs: red, yellow, and green.

The goal is to understand how embedded systems manage timed sequences and state changes. This is an important concept used in automation, industrial machines, and robotics.

Components Required

• Arduino Uno
• 3 LEDs (Red, Yellow, Green)
• 3 x 220Ω Resistors
• Breadboard
• Jumper wires

Wiring Guide

Follow these steps:

1. Insert the three LEDs into the breadboard.
2. Connect a resistor to each LED's anode (long leg).
3. Connect:
   • Red LED → Pin 2
   • Yellow LED → Pin 3
   • Green LED → Pin 4
4. Connect all cathodes (short legs) to the ground rail.
5. Connect the ground rail to Arduino GND.

Each resistor ensures that the LEDs receive safe current levels.

Source Code

int red = 2;
int yellow = 3;
int green = 4;

void setup() {
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
}

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

  digitalWrite(yellow, HIGH);
  delay(2000);
  digitalWrite(yellow, LOW);

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

Code Explanation

Each LED is assigned to a digital pin. In the setup(), all pins are configured as outputs.

The loop() function controls the sequence:

• Green turns ON for 5 seconds (go signal)
• Yellow turns ON for 2 seconds (warning)
• Red turns ON for 5 seconds (stop)

This sequence repeats continuously, mimicking a real traffic light system. This introduces the idea of a state machine, where the system transitions between defined states.