/**
 * Ping.h :: A library for using a Parallax PING))) sensor in robotic applications.
 * 
 * @author Tom Malone <tmalone+arduino.software@gmail.com>
 * @copyright Released into the public domain.
 */

#ifndef Ping_h
#define Ping_h

#if ARDUINO < 100
#include <WProgram.h>
#else
#include <Arduino.h>
#endif

#include <string.h>

class Ping {

    private:
	    uint8_t _pin;	// Which pin the Ping))) sensor is connected to.
	    String _distanceUnit;    // The unit of measurement for returning distance to obstacle. 
																    // Possible units: cm, in, or raw.
																    // cm == centimeters
																    // in == inches
																    // raw == return the raw time of the pulse duration in microseconds
	    float _centimetersPerSecond;	// The speed of sound we're using (because its variable, by a number of factors), converted to cm/second.
	    int _collisionThreshold;	// How close the robot is allowed to get to an obstacle before forcing it to turn away.
	    float _centimetersToInches(float cmValue);	// Converts centimeters to inches.
	    unsigned long _pulseDuration;	// Stores the time it takes the ultrasound to travel to the obstacle and back.
	    
    public:
	    Ping(uint8_t pin, String distanceUnit);	// The constructor method
	    unsigned long ping();	// Sends the actual Ping))) pulse.
	    void activate();	// The activation method take care of activating the Ping))) sensor with a brief PWM pulse.
	    uint8_t getCollisionThreshold();	// Returns the value of _collisionThreshold.
	    void setCollisionThreshold(uint8_t threshold);	// Sets the value of _collisionThreshold.
	    uint16_t pulseTimeToCentimeters(unsigned long pulseDuration);	// Converts the pulse duration to centimeters
	    float pulseTimeToInches(unsigned long pulseDuration);	// Converts the pulse duration to inches.
	    String getDistanceUnit();	// Gets the distance unit the user wants his distances to be returned in.
	    String setDistanceUnit(String distanceUnit);	// Sets the distance unit the user wants his distances to be turned in.
};

#endif