// Parallax PING Sensor 
// by BARRAGAN <http://barraganstudio.com> 

int signalPin = 0;                // sensor signal pin connected to wiring pin 0 
long elapsedtime = 0;  
 
void setup() { 
  Serial.begin(9600);            
} 
 
void loop() { 
  elapsedtime = 0; 
  pinMode(signalPin, OUTPUT);     // set signalPin as OUTPUT 
 
  // Send 0-1-0 pulse to activate the sensor 
  digitalWrite(signalPin, LOW);  
  delayMicroseconds(2);  
  digitalWrite(signalPin, HIGH);  
  delayMicroseconds(5);  
  digitalWrite(signalPin, LOW);  
 
  // Listen to pulse   
  pinMode(signalPin, INPUT);      // set signalPin as INPUT 
  elapsedtime = pulseIn(signalPin, HIGH);  // get the length of the pusle while it is HIGH 
 
  // print value through Serial 
   
  Serial.println(elapsedtime, DEC); 
  delay(100); 
}