Ultrasonic.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008. All Rights Reserved.                                                         */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in $(WIND_BASE)/WPILib.  */
/*----------------------------------------------------------------------------*/

#ifndef ULTRASONIC_H_
#define ULTRASONIC_H_

#include "SensorBase.h"
#include "Task.h"
#include "PIDSource.h"

class Counter;
class DigitalInput;
class DigitalOutput;

class Ultrasonic: public SensorBase, public PIDSource
{
public:
        typedef enum {
                kInches = 0,
                kMilliMeters = 1
        } DistanceUnit;
        
        Ultrasonic(DigitalOutput *pingChannel, DigitalInput *echoChannel, DistanceUnit units = kInches);
        Ultrasonic(DigitalOutput &pingChannel, DigitalInput &echoChannel, DistanceUnit units = kInches);
        Ultrasonic(UINT32 pingChannel, UINT32 echoChannel, DistanceUnit units = kInches);
        Ultrasonic(UINT8 pingModuleNumber, UINT32 pingChannel,
                                                        UINT8 echoModuleNumber, UINT32 echoChannel, DistanceUnit units = kInches);
        virtual ~Ultrasonic();

        void Ping();
        bool IsRangeValid();
        static void SetAutomaticMode(bool enabling);
        double GetRangeInches();
        double GetRangeMM();
        bool IsEnabled() { return m_enabled; }
        void SetEnabled(bool enable) { m_enabled = enable; }
        
        double PIDGet();
        void SetDistanceUnits(DistanceUnit units);
        DistanceUnit GetDistanceUnits();

private:
        void Initialize();

        static void UltrasonicChecker();

        static const double kPingTime = 10 * 1e-6;      
        static const UINT32 kPriority = 90;     
        static const double kMaxUltrasonicTime = 0.1;   
        static const double kSpeedOfSoundInchesPerSec = 1130.0 * 12.0;

        static Task m_task; // task doing the round-robin automatic sensing
        static Ultrasonic *m_firstSensor; // head of the ultrasonic sensor list
        static bool m_automaticEnabled; // automatic round robin mode
        static SEM_ID m_semaphore; // synchronize access to the list of sensors

        DigitalInput *m_echoChannel;
        DigitalOutput *m_pingChannel;
        bool m_allocatedChannels;
        bool m_enabled;
        Counter *m_counter;
        Ultrasonic *m_nextSensor;
        
        DistanceUnit m_units;
};

#endif