//define variables
#define trigerpin 12
#define echopin 13
#define ledpin 2
#define speakerpin 10
#define pitch 800
double duration, distance;

void setup() {
  //setup for sensor
  Serial.begin(9600);
  pinMode(trigerpin, OUTPUT);
  pinMode(echopin, INPUT);

  //setup for led
  pinMode(ledpin,OUTPUT);

  //setup for speaker
  pinMode(speakerpin,OUTPUT);



}

void loop() {
  //loopin sensor
  digitalWrite(trigerpin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigerpin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigerpin,LOW);
  delayMicroseconds(2);

  //get duration
  duration = pulseIn(echopin,HIGH);

  //calculate distance
  distance = (duration/2) * 0.0343;
  
  //consider maxium width of the door = 200 cm

  if(distance<200){
    digitalWrite(ledpin, HIGH);
    tone(speakerpin,pitch);
    delay(300);

    digitalWrite(ledpin, LOW);
    noTone(speakerpin);
    delay(300);

  }
  else{
    digitalWrite(ledpin, LOW);
    noTone(speakerpin);
  }

  }