PID algorithm for PIC18Fxxxx in C18

[wael_sal]

pid algorithm

Hi,
I trying to implement a PID algorithm in my code, I had referred to AN899 PID_main, yet the problem I am not familiar with assembly,
I need to use it for close loop speed control, is there any example code of PID inmlemented for PIC18F in C18?
I hope if any body familiar with PID routine to share his experience.

Best Regards
Wael
:?:

 

[chanchal.chauhan]

how is pi measured

What type of control you are looking

Just go through the website. You will get some more information for PID control
https://www.picontrolsolutions.com/

Please give more details about your project than only anyone help you properly.

Regards
Chanchal

 

[wael_sal]

c18 float example

What type of control you are looking

Just go through the website. You will get some more information for PID control
https://www.picontrolsolutions.com/

Please give more details about your project than only anyone help you properly.

Regards
Chanchal

what the relation between the site you post and my question?
Regards

 

[chanchal.chauhan]

pid pic18

Just try to understand.
If the site is useful than try to read it else leave it.


Regards
Chanchal

 

[btbass]

pid speed control algorithm

I have used a Pi controller for motor speed control using the Pic18f4431.
A Pi controller is usually enough for motor speed control.
Code space was not a probllem for me so I used float variables. One advantage with floats is you dont need to worry to much about overflow.
Tune the response by tweeking the float kCoeffs[] values.

In the init routine you set the 'Pi->Output' to your start up speed and then use that value to control the motor. IE:

PiCalc(&Pi);
pwm duty = (unsigned int)Pi->Output';

/*--------------------------------------------------------------------

  Title       : Header file for Pi controller. 
  Filename    : Pi.h
 
---------------------------------------------------------------------*/
 
 
/*--- Pi structure ---*/

typedef struct 
  {
  float Gain[2];    /* Pi gain values - Kp and Ki */
  float History[2]; /* Delay-line samples */
  float Output;     /* Pi Controller Output  */
  float Measured;   /* Measured Output sample */
  float Setpoint;   /* Reference Input sample */
  }PI;
   
/*--- Function prototypes ---*/

void PiInit(PI *Pi);
void PiCalc(PI *Pi);  
   
/*--- End of file ---*/

/*--------------------------------------------------------------------

  Title       : Pi controller. 
  Filename    : Pi.c
  
----------------------------------------------------------------------*/

#include "Pi.h"
  
/*--- Global variables ---*/

PI Pi;
float kCoeffs[] = {0.5, 0.2}; 
      
/*--- Program entry ---*/

void main(void)
  {
  PiInit(&Pi);
  
  Pi.Setpoint = 1.3;
  Pi.Measured = 1.25;
  
  for(;;){
    PiCalc(&Pi);
    }
  }
   
/*--- Initialise Pi ---*/

void PiInit(PI *Pi)
  {
  Pi->Gain[0] = kCoeffs[0];
  Pi->Gain[1] = kCoeffs[1];
  
  Pi->History[0] = 0.0;
  Pi->History[1] = 0.0;
      
  Pi->Output = 100.0;
  Pi->Setpoint = 0.0;
  Pi->Measured = 0.0;
  }
  
/*--- Calculate Pi ---*/  
  
void PiCalc(PI *Pi)
  {
  Pi->History[0] = Pi->Setpoint - Pi->Measured;
  Pi->History[1] += Pi->History[0];  
  Pi->Output += Pi->History[0] * Pi->Gain[0];    
  Pi->Output += Pi->History[1] * Pi->Gain[1];  
  }     
    
/*--- End of file ---*/