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  1. #ifndef PID_v1_h
  2. #define PID_v1_h
  3.  
  4. typedef float FloatType;
  5. //typedef double floatType;
  6. #include <stdbool.h>
  7. #include <stdio.h>
  8.  
  9. //Constants used in some of the functions below
  10.  
  11. typedef enum
  12. {
  13.   PID_Mode_Automatic = 1,
  14.   PID_Mode_Manual    = 0
  15. } PidModeType;
  16.  
  17. typedef enum
  18. {
  19.   PID_Direction_Direct  = 0,
  20.   PID_Direction_Reverse = 1
  21. } PidDirectionType;
  22.  
  23.   static const FloatType MAX_KD_MIN = 0.01;    // Greater than 0 to avoid division by 0 in calculation of Kd term
  24.  
  25. typedef struct{
  26.   FloatType dispKp; // * we'll hold on to the tuning parameters in user-entered
  27.   FloatType dispKi; //   format for display purposes
  28.   FloatType dispKd; //
  29.  
  30.   FloatType kp;     // * (P)roportional Tuning Parameter
  31.   FloatType ki;     // * (I)ntegral Tuning Parameter
  32.   FloatType kd;     // * (D)erivative Tuning Parameter
  33.  
  34.   FloatType PTerm;  // * (P)roportional term contributing to the output
  35.   FloatType ITerm;  // * (I)ntegral term contributing to the output
  36.   FloatType DTerm;  // * (D)erivative term contributing to the output
  37.  
  38.   FloatType MaxKd;  // * Maximum derivative gain.
  39.                     //   set to 10-20 to avoid applying derivation
  40.                     //   to high frequency measurement noise.
  41.   PidModeType       mode;
  42.   PidDirectionType  controllerDirection;
  43.  
  44.   FloatType* myInput;   // * Pointers to the Input, Output, and Setpoint variables
  45.   FloatType* myOutput;  //   This creates a hard link between the variables and the
  46.   FloatType* mySetpoint; //   PID, freeing the user from having to constantly tell us
  47.                         //   what these values are.  with pointers we'll just know.
  48.  
  49.   uint32_t lastTime;
  50.   FloatType lastInput;
  51.  
  52.   uint32_t SampleTime;
  53.   FloatType outMin, outMax;
  54. }PidType;
  55.  
  56.   // commonly used functions **************************************************************************
  57.  
  58. //  constructor.  links the PID to the Input, Output, and
  59. //  Setpoint.  Initial tuning parameters are also set here
  60. void PID_init(PidType* pid,
  61.     FloatType* Input,
  62.     FloatType* Output,
  63.     FloatType* Setpoint,
  64.     FloatType kp,
  65.     FloatType ki,
  66.     FloatType kd,
  67.     PidDirectionType controllerDirection);
  68.  
  69. // sets PID to either Manual (0) or Auto (non-0)
  70. void PID_SetMode(PidType* pid, PidModeType mode);
  71.  
  72. // performs the PID calculation.  it should be
  73. // called every time loop() cycles. ON/OFF and
  74. // calculation frequency can be set using SetMode
  75. // SetSampleTime respectively
  76. bool PID_Compute(PidType* pid);
  77.  
  78. // clamps the output to a specific range. 0-255 by default, but
  79. // it's likely the user will want to change this depending on
  80. // the application
  81. void PID_SetOutputLimits(PidType* pid, FloatType min, FloatType max);
  82.   // available but not commonly used functions ********************************************************
  83.  
  84. // While most users will set the tunings once in the
  85. // constructor, this function gives the user the option
  86. // of changing tunings during runtime for Adaptive control
  87. void PID_SetTunings(PidType* pid, FloatType kp, FloatType ki, FloatType kd);
  88.  
  89. // Sets the Direction, or "Action" of the controller. DIRECT
  90. // means the output will increase when error is positive. REVERSE
  91. // means the opposite.  it's very unlikely that this will be needed
  92. // once it is set in the constructor.
  93. void PID_SetControllerDirection(PidType* pid, PidDirectionType Direction);
  94.  
  95. // sets the frequency, in Milliseconds, with which
  96. // the PID calculation is performed.  default is 100
  97. void PID_SetSampleTime(PidType* pid, uint32_t newSampleTime);
  98.  
  99. // set the maximum derivative gain.  default is 10.
  100. void PID_SetMaxKd(PidType* pid, FloatType newMaxKd);        
  101.  
  102. //Display functions ****************************************************************
  103. // These functions query the pid for interal values.
  104. //  they were created mainly for the pid front-end,
  105. // where it's important to know what is actually
  106. //  inside the PID.
  107. FloatType PID_GetKp(PidType* pid);
  108. FloatType PID_GetKi(PidType* pid);
  109. FloatType PID_GetKd(PidType* pid);
  110. FloatType PID_GetMin(PidType* pid);
  111. FloatType PID_GetMax(PidType* pid);
  112. uint32_t PID_GetSampleTime(PidType* pid);
  113. PidModeType PID_GetMode(PidType* pid);
  114. PidDirectionType PID_GetDirection(PidType* pid);
  115. FloatType PID_GetPTerm(PidType* pid);
  116. FloatType PID_GetITerm(PidType* pid);
  117. FloatType PID_GetDTerm(PidType* pid);
  118.  
  119. #endif
  120.  
  121.  
  122.