Ultrasonic light

1/*
2HC-SR05 pin   Arduino pin   Relay Board     Light      Plug
3  vcc           5V             X            x          x
4  Trig         pin 9           X            x          x
5  Echo         pin 8           X            x          x
6  Gnd          Gnd             Gnd          x          x
7   X           pin 12         signal pin    x          x
8   X           Vin            +V            x          x
9   x           x               NO           com        x
10   x           x               x            Gnd        Gnd
11   x           x              Com           x          Com         
12*/
13int s;
14int state=0; 
15void setup()  {
16  // initialize serial communication:
17  Serial.begin(9600);
18   pinMode(8,  INPUT);
19   pinMode(9, OUTPUT);
20   pinMode(12, OUTPUT);  
21   digitalWrite(9,  LOW);
22   digitalWrite(8, LOW);
23}
24
25void loop() {
26  
27  long duration,  inches, cm;
28
29  
30
31    digitalWrite(9, HIGH);
32    delayMicroseconds(5);
33    digitalWrite(9, LOW);
34    delayMicroseconds(5);
35 
36 
37  duration =  pulseIn(8, HIGH);
38
39  
40  inches = microsecondsToInches(duration);
41  cm  = microsecondsToCentimeters(duration);
42
43  Serial.print(inches);
44  Serial.print("in,  ");
45  Serial.print(cm);
46  Serial.print("cm");
47  Serial.println();
48
49  
50  if(inches<12){  //   change number too increase/decrease sensor range
51  digitalWrite(12, HIGH);
52    delay(10000);//change number for how long kight stays  on mil sec
53    }else{
54    digitalWrite(12, LOW);//change number too change  off state distance
55      }
56
57   delay(100);
58}
59
60long microsecondsToInches(long  microseconds) {
61 
62  return microseconds / 74 / 2;
63}
64
65long microsecondsToCentimeters(long  microseconds) {
66 
67  return microseconds / 29 / 2;
68}