Touchless Doorbell

1/*
2'DISTANCE SENSOR:
3Vcc goes to 5V on arduino
4Gnd goes to ground  pin on arduino.
5Trigger goes to pin 8 on the arduino.
6Echo goes to pin 9 on  the arduino.
7
8BUZZER:
9Positive leg goes to pin 12 on the arduino.
10Negative  leg goes to GND on arduino.
11*/
12int trigPin = 8;    
13int echoPin = 9;    
14
15  
16void setup() {
17  pinMode(trigPin, OUTPUT);
18  pinMode(echoPin, INPUT);
19  delay(100);
20}
21 
22void loop() {
23 
24  digitalWrite(trigPin, LOW);
25  delayMicroseconds(5);
26  digitalWrite(trigPin, HIGH);
27  delayMicroseconds(10);
28  digitalWrite(trigPin, LOW);
29
30  int duration = pulseIn(echoPin, HIGH);
31  delay(50);
32  
33  if (duration <= 600){
34    tone(12, 2000, 3000);
35  }
36
37  else{
38    noTone(12);
39    
40  }
41}