#include <Servo.h>

int trigPin = 9;    // TRIG pin for ultrasonic sensor
int echoPin = 8;   // ECHO pin for ultrasonic sensor
int servoPin = 11;  // Pin for the servo motor

Servo myServo;      // Create a servo object

void setup() {
  Serial.begin(9600); // Start serial communication
  pinMode(trigPin, OUTPUT); // Set TRIG pin as output
  pinMode(echoPin, INPUT);  // Set ECHO pin as input
  myServo.attach(servoPin);  // Attach the servo to the specified pin

  // Initialize the servo to the closed position (0 degrees)
  myServo.write(0);
  delay(1000); // Wait for the servo to reach the position
}

void loop() {
  long duration, distance;

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

  // Read the echo pin
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance in cm
  distance = (duration * 0.0343) / 2; // Speed of sound is 0.0343 cm/µs

  // Print the distance to the Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Check the distance and control the servo
  if (distance < 20) { // If an object is detected within 20 cm
    myServo.write(90); // Open the lid (adjust angle as needed)
    Serial.println("Lid Opened");
    Serial.println (" "); 
  } else {
    myServo.write(0); // Close the lid
    Serial.println("Lid Closed");
    Serial.println (" "); 
  }

  delay(500); // Wait for half a second before the next measurement
}