pid.cpp File Reference

PID controller source file. More...

#include "config.h"
#include "pid.h"

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Functions
void	PIDInit (int16_t p_factor, int16_t i_factor, int16_t d_factor, pidData_t *pid)
	Initialisation of PID controller parameters.
uint16_t	PIDController (int16_t setPoint, int16_t processValue, pidData_t *pid_st)
	PID control algorithm.
void	PIDResetIntegrator (pidData_t *pid_st)
	Resets the integrator in the PID regulator.

Detailed Description

PID controller source file.

This file contains the implementation of the PID controller.

Author

Nexperia: http://www.nexperia.com

Support Page

For additional support, visit: https://www.nexperia.com/support

Author

Aanas Sayed

Date

2024/03/08

Definition in file pid.cpp.

Function Documentation

PIDController()

uint16_t PIDController	(	int16_t	setPoint,
		int16_t	processValue,
		pidData_t *	pid_st )

PID control algorithm.

Calculates output from set point, process value, and PID status.

Parameters

setPoint	Desired value.
processValue	Measured value.
pid_st	PID status struct.

Returns

Calculated control output as a 16-bit unsigned integer.

Definition at line 56 of file pid.cpp.

{
  int32_t ret;
  int32_t temp;
  int16_t error;
 
  error = setPoint - processValue;
 
  // Calculate "P" term and limit error overflow
  if (error > pid_st->maxError)
  {
    pid_st->p_term = MAX_INT;
  }
  else if (error < -pid_st->maxError)
  {
    pid_st->p_term = -MAX_INT;
  }
  else
  {
    pid_st->p_term = pid_st->P_Factor * error / 1000;
  }
 
  // Calculate "I" term and limit integral runaway.
  // i_term is always derived from sumError so the clamp is continuous.
  temp = pid_st->sumError + error;
  if (temp > pid_st->maxSumError)
  {
    pid_st->sumError = pid_st->maxSumError;
  }
  else if (temp < -pid_st->maxSumError)
  {
    pid_st->sumError = -pid_st->maxSumError;
  }
  else
  {
    pid_st->sumError = temp;
  }
  pid_st->i_term = pid_st->I_Factor * pid_st->sumError / 1000;
 
#if (PID_K_D_ENABLE == TRUE)
  // Calculate "D" term
  pid_st->d_term = pid_st->D_Factor * (pid_st->lastProcessValue - processValue) / 1000;
#endif
 
  pid_st->lastProcessValue = processValue;
 
#if (PID_K_D_ENABLE == TRUE)
  ret = (pid_st->p_term + pid_st->i_term + pid_st->d_term);
#else
  ret = (pid_st->p_term + pid_st->i_term);
#endif
 
#if (SCALING_FACTOR_ENABLED == TRUE)
  ret = ret / SCALING_FACTOR;
#endif
  if (ret > MAX_INT)
  {
    ret = MAX_INT;
  }
  // Since the return type is uint16_t
  else if (ret < 0)
  {
    ret = 0;
  }
 
  return ((uint16_t)ret);
}

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PIDInit()

void PIDInit	(	int16_t	p_factor,
		int16_t	i_factor,
		int16_t	d_factor,
		pidData_t *	pid )

Initialisation of PID controller parameters.

Initialise the variables used by the PID algorithm.

Parameters

p_factor	Proportional term.
i_factor	Integral term.
d_factor	Derivate term.
pid	Struct with PID status.

Definition at line 33 of file pid.cpp.

{
  // Start values for PID controller
  pid->sumError = 0;
  pid->lastProcessValue = 0;
  // Tuning constants for PID loop
  pid->P_Factor = p_factor;
  pid->I_Factor = i_factor;
  pid->D_Factor = d_factor;
  // Limits to avoid overflow
  pid->maxError = MAX_INT / pid->P_Factor;
  pid->maxSumError = MAX_I_TERM / pid->I_Factor;
}

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PIDResetIntegrator()

void PIDResetIntegrator

(

pidData_t *

pid_st

)

Resets the integrator in the PID regulator.

Calling this function will reset the integrator in the PID regulator.

Parameters

pid_st

Pointer to the PID status struct for which the integrator will be reset.

Definition at line 131 of file pid.cpp.

{
  pid_st->sumError = 0;
  pid_st->p_term = 0;
  pid_st->i_term = 0;
#if (PID_K_D_ENABLE == TRUE)
  pid_st->d_term = 0;
#endif
}

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