PID_v1.h

#ifndef PID_v1_h
#define PID_v1_h
#define LIBRARY_VERSION	1.1.1

class PID
{

public:

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

  //commonly used functions **************************************************************************
  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 SetMode(int Mode);               // * sets PID to either Manual (0) or Auto (non-0)

  bool Compute(bool forceCompute);      // * 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, double);       // * While most users will set the tunings once in the 
           	                                 //   constructor, this function gives the user the option
                                                 //   of changing tunings during runtime for Adaptive control
                                                 
  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;

  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 ITerm, lastInput;

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