// Define the pins for the ultrasonic sensor
const int trigPin = 9; // Trigger pin of the sensor
const int echoPin = 10; // Echo pin of the sensor

// Define the pins for the indicator LEDs
const int greenLed = 3; // Green LED pin
const int yellowLed = 5; // Yellow LED pin
const int redLed = 6; // Red LED pin

// Define the distance thresholds for indicating proximity
const int greenThreshold = 100; // Green LED threshold in cm
const int yellowThreshold = 50; // Yellow LED threshold in cm
const int redThreshold = 10; // Red LED threshold in cm

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);

  // Initialize ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Initialize LED pins
  pinMode(greenLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(redLed, OUTPUT);
}

void loop() {
  // Trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the echo pulse duration
  long duration = pulseIn(echoPin, HIGH);

  // Calculate distance in cm
  int distance = duration * 0.034 / 2;

  // Print distance to serial monitor for debugging
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Turn off all LEDs
  digitalWrite(greenLed, LOW);
  digitalWrite(yellowLed, LOW);
  digitalWrite(redLed, LOW);

  // Determine which LED to light based on distance
  if (distance > greenThreshold) {
    digitalWrite(greenLed, HIGH);
  } else if (distance > yellowThreshold) {
    digitalWrite(yellowLed, HIGH);
  } else if (distance > redThreshold) {
    digitalWrite(redLed, HIGH);
  } else {
    // Distance less than red threshold
    digitalWrite(redLed, HIGH);
  }

  // Delay before taking next reading
  delay(500); // Adjust the delay based on your requirements
}