main.c File Reference

Detailed Description

Example of use of general PID implementation for AVR.

Example of how to setup and use the general PID implementation in pid.c.

Author:
Atmel Corporation: http://www.atmel.com
Support email: avr@atmel.com
$Name$
Revision
456
$RCSfile$
Date
2006-02-16 12:46:13 +0100 (to, 16 feb 2006)

Definition in file main.c.

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

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Data Structures

struct  GLOBAL_FLAGS
 Flags for status information. More...

Defines

#define K_D   0.00
#define K_I   0.00
#define K_P   1.00
#define TIME_INTERVAL   157

Functions

int16_t Get_Measurement (void)
 Read system process value.
int16_t Get_Reference (void)
 Read reference value.
void Init (void)
 Init of PID controller demo.
void main (void)
 Demo of PID controller.
void Set_Input (int16_t inputValue)
 Set control input to system.
__interrupt void TIMER0_OVF_ISR (void)
 Timer interrupt to control the sampling interval.

Variables

GLOBAL_FLAGS gFlags
 Flags for status information.
PID_DATA pidData
 Parameters for regulator.

Define Documentation

#define K_D   0.00

Todo:

Definition at line 37 of file main.c.

Referenced by Init().

#define K_I   0.00

Todo:

Definition at line 35 of file main.c.

Referenced by Init().

#define K_P   1.00

The K_P, K_I and K_D values (P, I and D gains) need to be modified to adapt to the application at hand

Todo:

Definition at line 33 of file main.c.

Referenced by Init().

#define TIME_INTERVAL   157

Specify the desired PID sample time interval With a 8-bit counter (255 cylces to overflow), the time interval value is calculated as follows: TIME_INTERVAL = ( desired interval [sec] ) * ( frequency [Hz] ) / 255

Todo:

Definition at line 57 of file main.c.

Referenced by TIMER0_OVF_ISR().

Function Documentation

int16_t Get_Measurement ( void   ) 

Read system process value.

This function must return the measured data

Definition at line 99 of file main.c.

Referenced by main().

00100 {
00101   return 4;
00102 }

int16_t Get_Reference ( void   ) 

Read reference value.

This function must return the reference value. May be constant or varying

Definition at line 90 of file main.c.

Referenced by main().

00091 {
00092   return 8;
00093 }

void Init ( void   ) 

Init of PID controller demo.

Definition at line 75 of file main.c.

References K_D, K_I, K_P, pid_Init(), pidData, and SCALING_FACTOR.

Referenced by main().

00076 {
00077   pid_Init(K_P * SCALING_FACTOR, K_I * SCALING_FACTOR , K_D * SCALING_FACTOR , &pidData);
00078 
00079   // Set up timer, enable timer/counte 0 overflow interrupt
00080   TCCR0A = (1<<CS00);
00081   TIMSK0 = (1<<TOIE0);
00082   TCNT0 = 0;
00083 }

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void main ( void   ) 

Demo of PID controller.

Definition at line 117 of file main.c.

References FALSE, Get_Measurement(), Get_Reference(), gFlags, Init(), pid_Controller(), pidData, GLOBAL_FLAGS::pidTimer, and Set_Input().

00118 {
00119   int16_t referenceValue, measurementValue, inputValue;
00120   Init();
00121   __enable_interrupt();
00122 
00123   while(1){
00124 
00125     // Run PID calculations once every PID timer timeout
00126     if(gFlags.pidTimer)
00127     {
00128       referenceValue = Get_Reference();
00129       measurementValue = Get_Measurement();
00130 
00131       inputValue = pid_Controller(referenceValue, measurementValue, &pidData);
00132 
00133       Set_Input(inputValue);
00134 
00135       gFlags.pidTimer = FALSE;
00136     }
00137   }
00138 }

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void Set_Input ( int16_t  inputValue  ) 

Set control input to system.

Set the output from the controller as input to system.

Definition at line 109 of file main.c.

Referenced by main().

00110 {
00111   ;
00112 }

__interrupt void TIMER0_OVF_ISR ( void   ) 

Timer interrupt to control the sampling interval.

Definition at line 62 of file main.c.

References gFlags, GLOBAL_FLAGS::pidTimer, TIME_INTERVAL, and TRUE.

00063 {
00064   static uint16_t i = 0;
00065   if(i < TIME_INTERVAL)
00066     i++;
00067   else{
00068     gFlags.pidTimer = TRUE;
00069     i = 0;
00070   }
00071 }

Variable Documentation

struct GLOBAL_FLAGS gFlags

Flags for status information.

Referenced by main(), and TIMER0_OVF_ISR().

struct PID_DATA pidData

Parameters for regulator.

Definition at line 48 of file main.c.

Referenced by Init(), and main().

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