Water Pump Automation with Ultrasonic Sensor

1const int trigPin = 12;
2const int echoPin = 13;
3
4const int R_LED  = A0;
5const int G_LED = A1;
6const int Relay = A2;
7
8
9int duration  = 0;
10int distance = 0;
11
12void setup() 
13{
14  pinMode(trigPin , OUTPUT);
15  pinMode(echoPin , INPUT);
16  
17  pinMode(R_LED , OUTPUT);
18  pinMode(G_LED  , OUTPUT);
19  pinMode(Relay , OUTPUT);
20
21  
22  Serial.begin(9600);
23
24}
25
26void  loop()
27{
28 digitalWrite(trigPin, LOW);
29  delayMicroseconds(2);
30  digitalWrite(trigPin,  HIGH);
31  delayMicroseconds(10);
32  digitalWrite(trigPin, LOW);  
33  duration  = pulseIn(echoPin, HIGH);
34  distance = duration/58.2;
35
36  if ( distance  <= 4 )  // set value when you want to turn OFF water pump
37  {
38    digitalWrite(R_LED,  HIGH);
39    digitalWrite(G_LED, LOW);
40    digitalWrite(Relay, LOW);
41  }
42  else if ( distance >= 7 )   // set value when you want to turn ON water pump
43  {
44    digitalWrite(R_LED, LOW);
45    digitalWrite(G_LED, HIGH);
46    digitalWrite(Relay,  HIGH);
47  }
48  
49  delay(500);
50}
51