pid.c File Reference

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Detailed Description

PID controller.

This file contains the PID controller, based on the AVR221 application note.

Application note:

AVR447: Sinusoidal driving of three-phase permanent motor using ATmega48/88/168

Documentation

For comprehensive code documentation, supported compilers, compiler settings and supported devices see readme.html

Author:

Atmel Corporation: http://www.atmel.com
Support email: avr@atmel.com

Name

RELEASE_1_0

Revision

1.2

RCSfile

pid.c,v

Date

2006/03/16 08:00:21

Definition in file pid.c.

#include <ioavr.h>
#include "stdint.h"
#include "pid.h"

Include dependency graph for pid.c:

Go to the source code of this file.

Functions
int16_t	PID_Controller (int16_t setPoint, int16_t processValue, pidData_t *pid_st)
	PID control algorithm.
void	PID_Init (int16_t p_factor, int16_t i_factor, int16_t d_factor, pidData_t *pid)
	Initialisation of PID controller parameters.
void	PID_Reset_Integrator (pidData_t *pid_st)
	Resets the integrator.

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Function Documentation

int16_t PID_Controller (  int16_t  setPoint, int16_t  processValue, pidData_t *  pid_st )

PID control algorithm. Calculates output from setpoint, process value and PID status. Parameters: setPoint  Desired value. processValue  Measured value. pid_st  PID status struct. Definition at line 65 of file pid.c. References pidData::D_Factor, pidData::I_Factor, pidData::lastProcessValue, MAX_I_TERM, MAX_INT, pidData::maxError, pidData::maxSumError, pidData::P_Factor, SCALING_FACTOR, and pidData::sumError. Referenced by SpeedController(). { int16_t error, p_term, d_term; int32_t i_term; int32_t ret; int32_t temp; error = setPoint - processValue; // Calculate Pterm and limit error overflow if (error > pid_st->maxError) { p_term = MAX_INT; } else if (error < -pid_st->maxError) { p_term = -MAX_INT; } else { p_term = pid_st->P_Factor * error; } // Calculate Iterm and limit integral runaway temp = pid_st->sumError + error; if(temp > pid_st->maxSumError) { i_term = MAX_I_TERM; pid_st->sumError = pid_st->maxSumError; } else if(temp < -pid_st->maxSumError) { i_term = -MAX_I_TERM; pid_st->sumError = -pid_st->maxSumError; } else { pid_st->sumError = temp; i_term = pid_st->I_Factor * pid_st->sumError; } // Calculate Dterm d_term = pid_st->D_Factor * (pid_st->lastProcessValue - processValue); pid_st->lastProcessValue = processValue; ret = (p_term + i_term + d_term) / SCALING_FACTOR; if(ret > MAX_INT) { ret = MAX_INT; } else if(ret < -MAX_INT) { ret = -MAX_INT; } return((int16_t)ret); }

void PID_Init (  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 41 of file pid.c. References pidData::D_Factor, pidData::I_Factor, pidData::lastProcessValue, MAX_I_TERM, MAX_INT, pidData::maxError, pidData::maxSumError, pidData::P_Factor, and pidData::sumError. Referenced by main(). { // 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; }

void PID_Reset_Integrator (  pidData_t *  pid_st  )

Resets the integrator. Calling this function will reset the integrator in the PID regulator. Definition at line 129 of file pid.c. References pidData::sumError. Referenced by CommutationTicksUpdate(). { pid_st->sumError = 0; }

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