#include <Servo.h>

// Define pins for the ultrasonic sensor
const int trigPin = 9;
const int echoPin = 10;

// Define the servo pin
const int servoPin = 11;

// Create a servo object
Servo myServo;

// Variables to store the distance
long duration;
int distance;

void setup() {
  // Initialize serial communication for debugging
  Serial.begin(9600);
  
  // Set the trigPin as an output and the echoPin as an input
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Attach the servo to the servo pin
  myServo.attach(servoPin);
  
  // Set the initial position of the servo
  myServo.write(0); // Servo in closed position
}

void loop() {
  // Send a trigger signal to the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Read the echo signal
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate the distance in centimeters
  distance = duration * 0.034 / 2;
  
  // Print the distance for debugging
  Serial.print("Distance: ");
  Serial.println(distance);
  
  // If the obstacle is within 20 cm, move the servo to open
  if (distance <= 20) {
    myServo.write(90); // Open position
    delay(2000); // Keep it open for 2 seconds
  } else {
    // Move the servo back to the closed position
    myServo.write(0); // Closed position
  }

  delay(500); // Small delay to avoid rapid movement
}