#include <Servo.h>

const int trigPin = 9;
const int echoPin = 10;
const int servoPin = 6;

Servo doorServo;

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  doorServo.attach(servoPin);
  Serial.begin(9600);
}

void loop() {
  long duration;
  int distance;

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

  // Read echo time
  duration = pulseIn(echoPin, HIGH);

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

  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  if (distance > 0 && distance < 50) {
    // Person detected nearby
    doorServo.write(90);  // Open door
    delay(3000);          // Wait 3 seconds
    doorServo.write(0);   // Close door
  }

  delay(500);
}