Automatic water dispenser

                Code 

 //Ultasonic Sensor

//Pins connected to the ultrasonic sensor

#define trigPin  2

#define echoPin 3

//LED pins

#define led 9

#define pump 8

int range = 5;//range in inches

void setup() {

  // initialize serial communication:

  Serial.begin(9600);

  //initialize the sensor pins

  pinMode(trigPin, OUTPUT);

  pinMode(echoPin, INPUT);

  //initialize LED pins

  pinMode(led, OUTPUT);

  pinMode(pump, OUTPUT);

  //set LEDs

  digitalWrite(led, HIGH);

  digitalWrite(pump, LOW);

  

}

void loop()

{

  // establish variables for duration of the ping, 

  // and the distance result in inches and centimeters:

  long duration, inches, cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.

  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(5);

  digitalWrite(trigPin, LOW);

  // Take reading on echo pin

  duration = pulseIn(echoPin, HIGH);

  // convert the time into a distance

  inches = microsecondsToInches(duration);

  cm = microsecondsToCentimeters(duration);

  

  Serial.print(inches);

  Serial.print("in, ");

  Serial.print(cm);

  Serial.print("cm");

  Serial.println();

  

  if(inches < 5) {

    Serial.println("hand puted");

    digitalWrite(led, HIGH);

    digitalWrite(pump, LOW); 

     

    delay(100);

  } else {

    Serial.println("no hand");

     digitalWrite(pump, HIGH); 

     digitalWrite(led, LOW);

     delay(100);

  }  

  

  delay(200);

}

long microsecondsToInches(long microseconds)

{

  return microseconds / 74 / 2;

}

long microsecondsToCentimeters(long microseconds)

{

  // The speed of sound is 340 m/s or 29 microseconds per centimeter.

  // The ping travels out and back, so to find the distance of the

  // object we take half of the distance travelled.

  return microseconds / 29 / 2;

}