#include <Servo.h>

// define pins for ultrasonic sensor
const int trigPin = 10;
const int echoPin = 11;

// define pin for servo
const int servoPin = 9;

// define variables for distance measurement
long duration;
int distance;

// create a servo object
Servo myServo;

void setup() {
  // initialize serial communication
  Serial.begin(9600);

  // define the pin modes
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(servoPin, OUTPUT);

  // attach the servo to the corresponding pin
  myServo.attach(servoPin);
}

void loop() {
  // generate a pulse to trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // measure the duration of the pulse from the ultrasonic sensor
  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");

  // check if an object is detected within 50 centimeters
  if (distance < 50) {
    // rotate the servo to 90 degrees
    myServo.write(180);
    Serial.println("OPEN");

    // wait for 5 seconds
    delay(5000);

    // measure the distance again
    duration = pulseIn(echoPin, HIGH);
    distance = duration * 0.034 / 2;

    // check if the object is still there
    if (distance < 50) {
      // keep the servo at 180 degrees
      myServo.write(180);
      Serial.println("OPEN");
    } else {
      // return the servo to the initial position
      myServo.write(0);
      Serial.println("CLOSED");
    }
  } else {
    // return the servo to the initial position
    myServo.write(0);
    Serial.println("CLOSED");
  }

  // wait for some time before measuring the distance again
  delay(500);
}