#include <Servo.h>

#define TRIG 6
#define ECHO 7
#define SERVO_PIN 9

Servo doorLock;

void setup() {
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  doorLock.attach(SERVO_PIN);
  doorLock.write(0); // Door initially locked
  Serial.begin(9600);
}

void loop() {
  long duration;
  int distance;
  
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);

  duration = pulseIn(ECHO, HIGH);
  distance = duration * 0.034 / 2; 

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

  if (distance > 0 && distance <= 30) { 
    Serial.println("Person detected! Unlocking door...");
    doorLock.write(90); 
    delay(5000); 
    doorLock.write(0); 
    Serial.println("Door Locked!");
  }

  delay(1000);
}