Aqib
Published

Density Based Traffic Light Controller Using Arduino

If there will be no traffic on the other signal, one shouldn’t wait for that signal. System will skip that signal and will move on next one.

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Density Based Traffic Light Controller Using Arduino

Things used in this project

Hardware components

Arduino Mega 2560
Arduino Mega 2560
×1
Ultrasonic Sensor - HC-SR04 (Generic)
Ultrasonic Sensor - HC-SR04 (Generic)
×4
5 mm LED: Red
5 mm LED: Red
×5
5 mm LED: Green
5 mm LED: Green
×4
5 mm LED: Yellow
5 mm LED: Yellow
×4
Resistor 220 ohm
Resistor 220 ohm
×12
Jumper wires (generic)
Jumper wires (generic)
×1
Breadboard (generic)
Breadboard (generic)
×1

Software apps and online services

Arduino IDE
Arduino IDE

Story

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Schematics

Circuit Diagram

Code

Code

Arduino
#include<TimerOne.h>

int signal1[] = {23, 25, 27};
int signal2[] = {46, 48, 50};
int signal3[] = {13, 12, 11};
int signal4[] = {10, 9, 8};

int redDelay = 5000;
int yellowDelay = 2000;

volatile int triggerpin1 = 31;    
volatile int echopin1 = 29;       
volatile int triggerpin2 = 44;     
volatile int echopin2 = 42;        
volatile int triggerpin3 = 7;    
volatile int echopin3 = 6;       
volatile int triggerpin4 = 5;    
volatile int echopin4 = 4;       

volatile long time;                    // Variable for storing the time traveled
volatile int S1, S2, S3, S4;           // Variables for storing the distance covered

int t = 5;  // distance under which it will look for vehicles.

void setup(){
  Serial.begin(115200);
  Timer1.initialize(100000);  //Begin using the timer. This function must be called first. "microseconds" is the period of time the timer takes.
  Timer1.attachInterrupt(softInterr); //Run a function each time the timer period finishes.

  // Declaring LED pins as output
  for(int i=0; i<3; i++){
    pinMode(signal1[i], OUTPUT);
    pinMode(signal2[i], OUTPUT);
    pinMode(signal3[i], OUTPUT);
    pinMode(signal4[i], OUTPUT);
  }

  // Declaring ultrasonic sensor pins as output
  pinMode(triggerpin1, OUTPUT);  
  pinMode(echopin1, INPUT);      
  pinMode(triggerpin2, OUTPUT);  
  pinMode(echopin2, INPUT);
  pinMode(triggerpin3, OUTPUT);  
  pinMode(echopin3, INPUT);
  pinMode(triggerpin4, OUTPUT);  
  pinMode(echopin4, INPUT); 
}

void loop()
{
  // If there are vehicles at signal 1
  if(S1<t)
  {
    signal1Function();
  }

  // If there are vehicles at signal 2
  if(S2<t)
  {
    signal2Function();
  }

  // If there are vehicles at signal 3
  if(S3<t)
  {
    signal3Function();
  }

  // If there are vehicles at signal 4
  if(S4<t)
  {
    signal4Function();
  }
}

// This is interrupt function and it will run each time the timer period finishes. The timer period is set at 100 milli seconds.
void softInterr()
{
  // Reading from first ultrasonic sensor
  digitalWrite(triggerpin1, LOW);  
  delayMicroseconds(2);
  digitalWrite(triggerpin1, HIGH); 
  delayMicroseconds(10);
  digitalWrite(triggerpin1, LOW);
  time = pulseIn(echopin1, HIGH); 
  S1= time*0.034/2;

  // Reading from second ultrasonic sensor
  digitalWrite(triggerpin2, LOW);  
  delayMicroseconds(2);
  digitalWrite(triggerpin2, HIGH); 
  delayMicroseconds(10);
  digitalWrite(triggerpin2, LOW);
  time = pulseIn(echopin2, HIGH); 
  S2= time*0.034/2;

  // Reading from third ultrasonic sensor
  digitalWrite(triggerpin3, LOW);  
  delayMicroseconds(2);
  digitalWrite(triggerpin3, HIGH); 
  delayMicroseconds(10);
  digitalWrite(triggerpin3, LOW);
  time = pulseIn(echopin3, HIGH); 
  S3= time*0.034/2;

  // Reading from fourth ultrasonic sensor
  digitalWrite(triggerpin4, LOW);  
  delayMicroseconds(2);
  digitalWrite(triggerpin4, HIGH); 
  delayMicroseconds(10);
  digitalWrite(triggerpin4, LOW);
  time = pulseIn(echopin4, HIGH); 
  S4= time*0.034/2;

  // Print distance values on serial monitor for debugging
  Serial.print("S1: ");
  Serial.print(S1);
  Serial.print("  S2: ");
  Serial.print(S2);
  Serial.print("  S3: ");
  Serial.print(S3);
  Serial.print("  S4: ");
  Serial.println(S4);
}

void signal1Function()
{
  Serial.println("1");
  low();
  // Make RED LED LOW and make Green HIGH for 5 seconds
  digitalWrite(signal1[0], LOW);
  digitalWrite(signal1[2], HIGH);
  delay(redDelay);

  // if there are vehicels at other signals
  if(S2<t || S3<t || S4<t)
  {
    // Make Green LED LOW and make yellow LED HIGH for 2 seconds
    digitalWrite(signal1[2], LOW);
    digitalWrite(signal1[1], HIGH);
    delay(yellowDelay);
  }
}

void signal2Function()
{
  Serial.println("2");
  low();
  digitalWrite(signal2[0], LOW);
  digitalWrite(signal2[2], HIGH);
  delay(redDelay);
  
  if(S1<t || S3<t || S4<t)
  {
    digitalWrite(signal2[2], LOW);
    digitalWrite(signal2[1], HIGH);
    delay(yellowDelay);   
  }
}

void signal3Function()
{
  Serial.println("3");
  low();
  digitalWrite(signal3[0], LOW);
  digitalWrite(signal3[2], HIGH);
  delay(redDelay);

  if(S1<t || S2<t || S4<t)
  {
    digitalWrite(signal3[2], LOW);
    digitalWrite(signal3[1], HIGH);
    delay(yellowDelay);
  }  
}

void signal4Function()
{
  Serial.println("4");
  low();
  digitalWrite(signal4[0], LOW);
  digitalWrite(signal4[2], HIGH);
  delay(redDelay);

  if(S1<t || S2<t || S3<t)
  {
    digitalWrite(signal4[2], LOW);
    digitalWrite(signal4[1], HIGH);
    delay(yellowDelay);
  }
}

// Function to make all LED's LOW except RED one's.
void low()
{
  for(int i=1; i<3; i++)
  {
    digitalWrite(signal1[i], LOW);
    digitalWrite(signal2[i], LOW);
    digitalWrite(signal3[i], LOW);
    digitalWrite(signal4[i], LOW);
  }
  for(int i=0; i<1; i++)
  {
    digitalWrite(signal1[i], HIGH);
    digitalWrite(signal2[i], HIGH);
    digitalWrite(signal3[i], HIGH);
    digitalWrite(signal4[i], HIGH);
  }
}

Credits

Aqib

Aqib

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