// 2009 mlab.uiah.fi/paja
// PING))) Ultrasonic sensor

int pingPin = 7;  // This pin is connected pin SIG in PING))) Ultrasonic sensor 
int duration;

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  // Pulse out
  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // We give a short LOW pulse beforehand to ensure a clean HIGH pulse.

  pinMode(pingPin, OUTPUT);
  digitalWrite(pingPin, LOW);
  delayMicroseconds(2);
  digitalWrite(pingPin, HIGH);
  delayMicroseconds(5);
  digitalWrite(pingPin, LOW);
  
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);
  Serial.println(duration);
  
  delay(100);
}