Smart Traffic Light System Using Arduino: Complete DIY Guide

// Arduino Smart Traffic Light System
// Define LED pins for each direction

// Road 1 - North
int red1 = 2;
int yellow1 = 3;
int green1 = 4;

// Road 2 - East
int red2 = 5;
int yellow2 = 6;
int green2 = 7;

// Road 3 - South
int red3 = 8;
int yellow3 = 9;
int green3 = 10;

// Road 4 - West
int red4 = 11;
int yellow4 = 12;
int green4 = 13;

// Timing variables (in milliseconds)
int greenDelay = 5000;   // 5 seconds
int yellowDelay = 2000;  // 2 seconds

void setup() {
  // Initialize all LED pins as OUTPUT
  pinMode(red1, OUTPUT);
  pinMode(yellow1, OUTPUT);
  pinMode(green1, OUTPUT);
  
  pinMode(red2, OUTPUT);
  pinMode(yellow2, OUTPUT);
  pinMode(green2, OUTPUT);
  
  pinMode(red3, OUTPUT);
  pinMode(yellow3, OUTPUT);
  pinMode(green3, OUTPUT);
  
  pinMode(red4, OUTPUT);
  pinMode(yellow4, OUTPUT);
  pinMode(green4, OUTPUT);
  
  // Start with all red lights on (safe state)
  digitalWrite(red1, HIGH);
  digitalWrite(red2, HIGH);
  digitalWrite(red3, HIGH);
  digitalWrite(red4, HIGH);
}

void loop() {
  // Traffic Signal Sequence
  
  // Road 1 - Green (Others Red)
  trafficSignal(green1, yellow1, red1, red2, red3, red4);
  
  // Road 2 - Green (Others Red)
  trafficSignal(green2, yellow2, red2, red1, red3, red4);
  
  // Road 3 - Green (Others Red)
  trafficSignal(green3, yellow3, red3, red1, red2, red4);
  
  // Road 4 - Green (Others Red)
  trafficSignal(green4, yellow4, red4, red1, red2, red3);
}

// Function to control traffic signal sequence
void trafficSignal(int green, int yellow, int red, int r2, int r3, int r4) {
  // Turn on green light
  digitalWrite(green, HIGH);
  digitalWrite(yellow, LOW);
  digitalWrite(red, LOW);
  
  // Keep other roads red
  digitalWrite(r2, HIGH);
  digitalWrite(r3, HIGH);
  digitalWrite(r4, HIGH);
  
  delay(greenDelay);
  
  // Switch to yellow
  digitalWrite(green, LOW);
  digitalWrite(yellow, HIGH);
  delay(yellowDelay);
  
  // Switch to red
  digitalWrite(yellow, LOW);
  digitalWrite(red, HIGH);
  delay(1000); // Brief pause before next signal
}