Servo.h

#ifndef SR04_H
#define SR04_H

#if defined(ARDUINO) && ARDUINO >= 100
   #include "Arduino.h"
#else
   #include "WProgram.h"
#endif
 //#include "pins_arduino.h"
 
#include <inttypes.h>

#define PULSE_TIMEOUT 150000L	// 100ms
#define DEFAULT_DELAY 10
#define DEFAULT_PINGS 5
class SR04 {
public:

/**
* Constructor
* Ultrasonic sensor SR04, four connections pins
* VCC, ECHO, TRIGGER, GND
* 

* \param echoPin digital INPUT-Pin for measuring distance
 * \param triggerPin if 10us high a trigger signal is generated from 
 *					SR04
 *
 * \return void
 */
 SR04(int echoPin, int triggerPin);

 /**
 * Do a measurment for this sensor. Return distance as long
 * in centimenter
 * \return long distance in centimeter
 */
 long Distance();
 
 /**
 * Do count measurents and calculate the average. 
 * To avoid defilement from ow/high peaks, min/max values
 * are substracted from the average
 *
 * \param wait delay between measurements, default = DEFAULT_DELAY/ms
 * \param count number of measurements, default DEFAULT_PINGS
 * \return long distance in centimeter
 **/
 long DistanceAvg(int wait=DEFAULT_DELAY, int count=DEFAULT_PINGS);
 
 /**
 * Do only a ping. Get result with methode getDistance()
 * 
 * \param keine
 */
 void Ping() ;
 
 /**
 * return latest distance. Methode Ping() should be called before
 * \param keine
 * \return Distanz in Zentimeter
 */
 long getDistance();


private:
 /**
 * Do the measurement calculation and return result in centimeter
 * SR04 measure echo time to obstacle and return way. 
 * 

 * Sound travels with 340m/sec
 * 

 * Example: Obstace 100cm away from SR04. Measure time is 100cm to
 * obstacle and 100cm return = 200cm
 * 

 * 1sec = 1000ms = 1.000.000uS
 * 1.000.000 / 340 = Distance in microseconds for 100cm
 * 2941uS fuer 100cm = 5882 uS fuer 200cm
 *
 * duration / 5882 * 100 = distance in cm
 */	
 long MicrosecondsToCentimeter(long duration);
 long _currentDistance;
 int _echoPin, _triggerPin;
 long _duration, _distance;
 bool _autoMode;
};
#endif