pid.h File Reference

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Detailed Description

PID controller header file.

This file contains defines, typedefs and prototypes for the PID controller.

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

1.3

RCSfile

pid.h,v

Date

2006/03/16 11:57:20

Definition in file pid.h.

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Go to the source code of this file.

Data Structures
struct	pidData
	PID Status. More...
Defines
#define	FALSE   0
	FALSE constant.
#define	MAX_I_TERM   (MAX_LONG - (2 * (int32_t)MAX_INT))
#define	MAX_INT   32767
	Maximum value of integers.
#define	MAX_LONG   2147483647L
	Maximum value of long integers.
#define	SCALING_FACTOR   256
	Scaling division factor for PID controller.
#define	TRUE   (!FALSE)
	TRUE constant.
Typedefs
typedef pidData	pidData_t
	PID Status.
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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Define Documentation

#define FALSE   0

FALSE constant. Definition at line 79 of file pid.h. Referenced by ActualDirectionUpdate(), CommutationTicksUpdate(), DirectionInputChangeISR(), HallChangeISR(), main(), and MotorSynchronizedUpdate().

#define MAX_I_TERM   (MAX_LONG - (2 * (int32_t)MAX_INT))

Maximum value of the I-term. This limits the maximum positive or negative value of the I-term. Changing this value leads to a different integral anti-windup limit. Do not increase this value from its default, as it is already at the limit of the underlying data types. Definition at line 75 of file pid.h. Referenced by PID_Controller(), and PID_Init().

#define MAX_INT   32767

Maximum value of integers. Definition at line 63 of file pid.h. Referenced by PID_Controller(), and PID_Init().

#define MAX_LONG   2147483647L

Maximum value of long integers. Definition at line 66 of file pid.h.

#define SCALING_FACTOR   256

Scaling division factor for PID controller. Scaling division factor for the PID controller. The P, I and D gains will be divided by this number. Definition at line 37 of file pid.h. Referenced by PID_Controller().

#define TRUE   (!FALSE)

TRUE constant. Definition at line 82 of file pid.h. Referenced by CommutationTicksUpdate(), MotorSynchronizedUpdate(), and Timer1CaptureISR().

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Typedef Documentation

typedef struct pidData pidData_t

PID Status. Setpoints and data used by the PID control algorithm

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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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