//define variables
#define triggerPin 12
#define echoPin 13
#define ledPin 2
#define speakerPin 10
#define pitch 262

double duration, distance;

void setup() {
  //setup for Sensor
  Serial.begin(9600);
  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);

  //setup for LED
  pinMode(ledPin, OUTPUT);

  //setup for Speaker
  pinMode(speakerPin, OUTPUT);

}

void loop() {
  //looping sensor
  digitalWrite(triggerPin,LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);

  //get duration
  duration = pulseIn(echoPin,HIGH);
   
   //calculate distance
   distance = (duration/2) * 0.0343;

   //consider maximum width of the door = 200cm

   if(distance<200){
     digitalWrite(ledPin, HIGH);
     tone(speakerPin,pitch);
     delay(300);
     
     digitalWrite(ledPin, LOW);
     noTone(speakerPin);
     delay(300);
     }
     else{
       digitalWrite(ledPin, LOW);
       noTone(speakerPin);
      }


}