#ifndef PID_H
#define PID_H
typedef float FloatType;
//typedef double floatType;
#include <stdbool.h>
//Constants used in some of the functions below
typedef enum
{
PID_Mode_Automatic = 1,
PID_Mode_Manual = 0
} PidModeType;
typedef enum
{
PID_Direction_Direct = 0,
PID_Direction_Reverse = 1
} PidDirectionType;
typedef struct {
FloatType dispKp; // * we'll hold on to the tuning parameters in user-entered
FloatType dispKi; // format for display purposes
FloatType dispKd; //
FloatType kp; // * (P)roportional Tuning Parameter
FloatType ki; // * (I)ntegral Tuning Parameter
FloatType kd; // * (D)erivative Tuning Parameter
PidDirectionType controllerDirection;
FloatType myInput; // * Pointers to the Input, Output, and Setpoint variables
FloatType myOutput; // This creates a hard link between the variables and the
FloatType mySetpoint; // PID, freeing the user from having to constantly tell us
// what these values are. with pointers we'll just know.
// unsigned long lastTime;
FloatType ITerm, lastInput;
unsigned long SampleTime;
FloatType outMin, outMax;
bool inAuto;
} PidType;
//commonly used functions **************************************************************************
// constructor. links the PID to the Input, Output, and
// Setpoint. Initial tuning parameters are also set here
void PID_init(PidType* pid,
FloatType kp,
FloatType ki,
FloatType kd,
PidDirectionType controllerDirection);
// sets PID to either Manual (0) or Auto (non-0)
void PID_SetMode(PidType* pid, PidModeType mode);
// performs the PID calculation. it should be
// called every time loop() cycles. ON/OFF and
// calculation frequency can be set using SetMode
// SetSampleTime respectively
bool PID_Compute(PidType* pid);
// 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
void PID_SetOutputLimits(PidType* pid, FloatType min, FloatType max);
//available but not commonly used functions ********************************************************
// 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 PID_SetTunings(PidType* pid, FloatType kp, FloatType ki, FloatType kd);
// 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 PID_SetControllerDirection(PidType* pid, PidDirectionType Direction);
// sets the frequency, in Milliseconds, with which
// the PID calculation is performed. default is 100
void PID_SetSampleTime(PidType* pid, int newSampleTime);
//Display functions ****************************************************************
// These functions query the pid for interal values.
// they were created mainly for the pid front-end,
// where it's important to know what is actually
// inside the PID.
FloatType PID_GetKp(PidType* pid);
FloatType PID_GetKi(PidType* pid);
FloatType PID_GetKd(PidType* pid);
PidModeType PID_GetMode(PidType* pid);
PidDirectionType PID_GetDirection(PidType* pid);
//void PID_Initialize(PidType* pid);
#endif/**********************************************************************************************
* C PID Library - Version 1.0.1
* modified my Matthew Blythe <mblythester@gmail.com> mjblythe.com/hacks
* originally by Brett Beauregard <br3ttb@gmail.com> brettbeauregard.com
*
* This Library is licensed under a GPLv3 License
**********************************************************************************************/
#include "pid.h"
void PID_Initialize(PidType* pid);
/*Constructor (...)*********************************************************
* The parameters specified here are those for for which we can't set up
* reliable defaults, so we need to have the user set them.
***************************************************************************/
void PID_init(PidType* pid, FloatType Kp, FloatType Ki, FloatType Kd,
PidDirectionType ControllerDirection) {
pid->myInput = 0;
pid->myOutput = 0;
pid->mySetpoint = 0;
pid->ITerm = 0;
pid->lastInput = 0;
pid->inAuto = false;
PID_SetOutputLimits(pid, 0, 0xffff);
//default Controller Sample Time is 1 seconds
pid->SampleTime = 1000;
PID_SetControllerDirection(pid, ControllerDirection);
PID_SetTunings(pid, Kp, Ki, Kd);
// pid->lastTime = millis() - pid->SampleTime;
}
/* Compute() **********************************************************************
* This, as they say, is where the magic happens. this function should be called
* every time "void loop()" executes. the function will decide for itself whether a new
* pid Output needs to be computed. returns true when the output is computed,
* false when nothing has been done.
**********************************************************************************/
bool PID_Compute(PidType* pid) {
if (!pid->inAuto) {
return false;
}
// unsigned long now = millis();
// unsigned long timeChange = (now - pid->lastTime);
// if (timeChange >= pid->SampleTime) {
/*Compute all the working error variables*/
FloatType input = pid->myInput;
FloatType error = pid->mySetpoint - input;
pid->ITerm += (pid->ki * error);
if (pid->ITerm > pid->outMax)
pid->ITerm = pid->outMax;
else if (pid->ITerm < pid->outMin)
pid->ITerm = pid->outMin;
FloatType dInput = (input - pid->lastInput);
/*Compute PID Output*/
FloatType output = pid->kp * error + pid->ITerm - pid->kd * dInput;
if (output > pid->outMax)
output = pid->outMax;
else if (output < pid->outMin)
output = pid->outMin;
pid->myOutput = output;
/*Remember some variables for next time*/
pid->lastInput = input;
// pid->lastTime = now;
return true;
// } else {
// return false;
// }
}
/* SetTunings(...)*************************************************************
* This function allows the controller's dynamic performance to be adjusted.
* it's called automatically from the constructor, but tunings can also
* be adjusted on the fly during normal operation
******************************************************************************/
void PID_SetTunings(PidType* pid, FloatType Kp, FloatType Ki, FloatType Kd) {
if (Kp < 0 || Ki < 0 || Kd < 0){
return;
}
pid->dispKp = Kp;
pid->dispKi = Ki;
pid->dispKd = Kd;
FloatType SampleTimeInSec = ((FloatType) pid->SampleTime) / 1000;
pid->kp = Kp;
pid->ki = Ki * SampleTimeInSec;
pid->kd = Kd / SampleTimeInSec;
if (pid->controllerDirection == PID_Direction_Reverse) {
pid->kp = (0 - pid->kp);
pid->ki = (0 - pid->ki);
pid->kd = (0 - pid->kd);
}
}
/* SetSampleTime(...) *********************************************************
* sets the period, in Milliseconds, at which the calculation is performed
******************************************************************************/
void PID_SetSampleTime(PidType* pid, int NewSampleTime) {
if (NewSampleTime > 0) {
FloatType ratio = (FloatType) NewSampleTime / (FloatType) pid->SampleTime;
pid->ki *= ratio;
pid->kd /= ratio;
pid->SampleTime = (unsigned long) NewSampleTime;
}
}
/* SetOutputLimits(...)****************************************************
* This function will be used far more often than SetInputLimits. while
* the input to the controller will generally be in the 0-1023 range (which is
* the default already,) the output will be a little different. maybe they'll
* be doing a time window and will need 0-8000 or something. or maybe they'll
* want to clamp it from 0-125. who knows. at any rate, that can all be done
* here.
**************************************************************************/
void PID_SetOutputLimits(PidType* pid, FloatType Min, FloatType Max) {
if (Min >= Max) {
return;
}
pid->outMin = Min;
pid->outMax = Max;
if (pid->inAuto) {
if (pid->myOutput > pid->outMax) {
pid->myOutput = pid->outMax;
} else if (pid->myOutput < pid->outMin) {
pid->myOutput = pid->outMin;
}
if (pid->ITerm > pid->outMax) {
pid->ITerm = pid->outMax;
} else if (pid->ITerm < pid->outMin) {
pid->ITerm = pid->outMin;
}
}
}
/* SetMode(...)****************************************************************
* Allows the controller Mode to be set to manual (0) or Automatic (non-zero)
* when the transition from manual to auto occurs, the controller is
* automatically initialized
******************************************************************************/
void PID_SetMode(PidType* pid, PidModeType Mode)
{
bool newAuto = (Mode == PID_Mode_Automatic);
if(newAuto != pid->inAuto)
{ /*we just went from manual to auto*/
PID_Initialize(pid);
}
pid->inAuto = newAuto;
}
/* Initialize()****************************************************************
* does all the things that need to happen to ensure a bumpless transfer
* from manual to automatic mode.
******************************************************************************/
void PID_Initialize(PidType* pid) {
pid->ITerm = pid->myOutput;
pid->lastInput = pid->myInput;
if (pid->ITerm > pid->outMax) {
pid->ITerm = pid->outMax;
} else if (pid->ITerm < pid->outMin) {
pid->ITerm = pid->outMin;
}
}
/* SetControllerDirection(...)*************************************************
* The PID will either be connected to a DIRECT acting process (+Output leads
* to +Input) or a REVERSE acting process(+Output leads to -Input.) we need to
* know which one, because otherwise we may increase the output when we should
* be decreasing. This is called from the constructor.
******************************************************************************/
void PID_SetControllerDirection(PidType* pid, PidDirectionType Direction) {
if (pid->inAuto && Direction != pid->controllerDirection) {
pid->kp = (0 - pid->kp);
pid->ki = (0 - pid->ki);
pid->kd = (0 - pid->kd);
}
pid->controllerDirection = Direction;
}
/* Status Funcions*************************************************************
* Just because you set the Kp=-1 doesn't mean it actually happened. these
* functions query the internal state of the PID. they're here for display
* purposes. this are the functions the PID Front-end uses for example
******************************************************************************/
FloatType PID_GetKp(PidType* pid) {
return pid->dispKp;
}
FloatType PID_GetKi(PidType* pid) {
return pid->dispKi;
}
FloatType PID_GetKd(PidType* pid) {
return pid->dispKd;
}
PidModeType PID_GetMode(PidType* pid) {
return pid->inAuto ? PID_Mode_Automatic : PID_Mode_Manual;
}
PidDirectionType PID_GetDirection(PidType* pid) {
return pid->controllerDirection;
}#include "PID.h"PidType PID;PID_init(&PID, 1, 0.05, 0.25, PID_Direction_Direct);
PID_SetMode(&PID, PID_Mode_Automatic);
PID_SetOutputLimits(&PID, PWM_Step, PWM_Period); PID.mySetpoint = SetTemp;
PID.myInput = RealTemp;
PID_Compute(&PID);
SetPWM = PID.myOutput;