const int trigPin = 2;    // Trigger pin of the HC-SR04
const int echoPin = 4;    // Echo pin of the HC-SR04
const int ledPin = 13;    // Digital pin for the LED
const int maxDistance = 200;  // Maximum distance in centimeters for mapping

void setup() {
  Serial.begin(115200);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Trigger the HC-SR04 to measure distance
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echo pin and calculate the distance
  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;

  // Map the distance to LED intensity
  int brightness = map(distance, 0, maxDistance, 255, 0);
  brightness = constrain(brightness, 0, 255);

  // Set the LED intensity
  analogWrite(ledPin, brightness);

  // Print distance and brightness to Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.print(" cm, Brightness: ");
  Serial.println(brightness);

  delay(500);  // Adjust the delay as needed
}