// Write a program for check the distanace by using ultrasonic sensor as per the distance controll the brightness of the led 
// Name: Rohit Kumar
// Reg. No: 12110865
// Roll No: 10


// Define pins
const int trigPin = 5;
const int echoPin = 18;
const int ledPin = 2;

// Variables
long duration;
int distance;
int brightness;

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  
  // Set up the sensor and LED pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  // Set the trigPin HIGH for 10 microseconds
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echoPin, returns the sound wave travel time in microseconds
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance in centimeters
  distance = duration * 0.034 / 2;
  
  // Print the distance to the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // Map the distance to a brightness level (0 to 255)
  brightness = map(distance, 0, 399, 255, 0);
  brightness = constrain(brightness, 0, 255); // Ensure the brightness is within the valid range
  
  // Set the brightness of the LED
  analogWrite(ledPin, brightness);
  
  // Delay before the next loop
  delay(100);
}