PID_v1.h

#ifndef PID_v1_h
#define PID_v1_h
#define LIBRARY_VERSION	1.2.1

//Constants used in some of the functions below
#define AUTOMATIC	1
#define MANUAL	0
#define DIRECT  0
#define REVERSE  1
#define P_ON_M 0
#define P_ON_E 1

class PID{ 
  public:
    PID() = default;                      // * I forgot why this is needed, but I'll invistigate later
  //commonly used functions **************************************************************************
    PID(double*, double*, double*,        // * constructor.  links the PID to the Input, Output, and 
        double, double, double, int, int);//   Setpoint.  Initial tuning parameters are also set here.
                                          //   (overload for specifying proportional mode)

    PID(double*, double*, double*,        // * constructor.  links the PID to the Input, Output, and 
        double, double, double, int);     //   Setpoint.  Initial tuning parameters are also set here
	
    void SetInput(double* newInput);   // * allows for changing the pointer to the input.
    
    void SetMode(int Mode);               // * sets PID to either Manual (0) or Auto (non-0)

    bool Compute();                       // * performs the PID calculation.  it should be
                                          //   called every time loop() cycles. ON/OFF and
                                          //   calculation frequency can be set using SetMode
                                          //   SetSampleTime respectively

    void SetOutputLimits(double, double); // * clamps the output to a specific range. 0-255 by default, but
										                      //   it's likely the user will want to change this depending on
										                      //   the application
	
  //available but not commonly used functions ********************************************************
    void SetTunings(double, double,       // * While most users will set the tunings once in the 
                    double);         	    //   constructor, this function gives the user the option
                                          //   of changing tunings during runtime for Adaptive control
    void SetTunings(double, double,       // * overload for specifying proportional mode
                    double, int);         	  

	  void SetControllerDirection(int);	    // * Sets the Direction, or "Action" of the controller. DIRECT
										                      //   means the output will increase when error is positive. REVERSE
										                      //   means the opposite.  it's very unlikely that this will be needed
										                      //   once it is set in the constructor.
    void SetSampleTime(int);              // * sets the frequency, in Milliseconds, with which 
                                          //   the PID calculation is performed.  default is 100
										  
    //Display functions ****************************************************************
    double GetKp();						  // These functions query the pid for interal values.
    double GetKi();						  //  they were created mainly for the pid front-end,
    double GetKd();						  // where it's important to know what is actually 
    int GetMode();						  //  inside the PID.
    int GetDirection();					//

  private:
    void Initialize();
    
    double dispKp;				      // * we'll hold on to the tuning parameters in user-entered 
    double dispKi;				      //   format for display purposes
    double dispKd;				      //
    
	  double kp;                  // * (P)roportional Tuning Parameter
    double ki;                  // * (I)ntegral Tuning Parameter
    double kd;                  // * (D)erivative Tuning Parameter

    int controllerDirection;
    int pOn;

    double *myInput;            // * Pointers to the Input, Output, and Setpoint variables
    double *myOutput;           //   This creates a hard link between the variables and the 
    double *mySetpoint;         //   PID, freeing the user from having to constantly tell us
                                //   what these values are.  with pointers we'll just know.
			  
    unsigned long lastTime;
    double outputSum, lastInput;

    unsigned long SampleTime;
    double outMin, outMax;
    bool inAuto, pOnE;
};
#endif