S12 / MagniV MicrocontrollersのトピックPWM read on HCS12 (Dragon 12)

PWM read on HCS12 (Dragon 12)

dragonVStiger — Fri, 24 Apr 2009 02:22:25 GMT

I am having a problem reading a pwm signal into my HCS12. I am using codewarrior. I have been working on this problem for a long time with limited to no success. I am using input capture to time rising and falling edges on the samee channel(0). At this point my interupt is only firing on rising eges, but i think i have the register set correctly for both rising and falling. Any advice would be greatly appreciated.

Here is what i have:

    sum = sum + diff ;


    if (cnt==100){


      dblsum=sum ;
      avg = dblsum/cnt;

      cnt = 0;
      sum = 0;
    }

    }

}

__interrupt void RealTimeInterrupt( void )
{
CRGFLG = 0x80;       /* clear rti flag */
}

__interrupt void TC0Interrupt( void )
{

TFLG1 = 0x01;     //clear TC0 flag

if(PTT &= 0x01){ //PT0 is high afte interupt
    rise = TC0;

} else                   //PT0 is low afte interupt

{

    fall = TC0;
    diff = fall - rise;
    cnt++ ;

}

}

__interrupt void TOI( void )
{

}

Re: PWM read on HCS12 (Dragon 12)

ipa — Fri, 24 Apr 2009 15:47:04 GMT

Hi,

My opinion: in TC0Interrupt routine, you may use PTIT register to

determine the level of input pin: if (PTIT & 0x01)...

Regards,

ipa

Re: PWM read on HCS12 (Dragon 12)

dragonVStiger — Wed, 29 Apr 2009 04:06:04 GMT

I have made some progess. My averging was causeing some problems, so i bypassed it. I am getting very accurate readings on the low end of my desired scale (1ms-10ms), but around 10ms and above i am getting an occasional extermly high reading, as the hightime lengthens this error occurs more frequently. Here's what i have now.

#include <hidef.h>      /* common defines and macros */
#include <mc9s12dg256.h>     /* derivative information */
#pragma LINK_INFO DERIVATIVE "mc9s12dg256b"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "main_asm.h" /* interface to the assembly module */
#define DLC_DELAY 300
#define PI 3.14159265

__interrupt void RealTimeInterrupt( void );
__interrupt void TC0Interrupt( void );
__interrupt void TOI( void );

volatile long unsigned int diff,rise,fall,last,ovcnt,sum=0,cnt,avg;
//float avg;
char string[17];
int debug = 1,debug2=2,debug3=3;
int flag = 0,flag2=0,flag3=0;
double dblsum;

void main( void ){

PLL_init();
LCD_init();
DDRT=0x00;                  //input

TSCR1= 0x80;                 // enable timer
TSCR2= 0b101;                // prescale 32
TIOS &= ~0x01;               // channel 0 input capture
TCTL4 = 0b11;                // capture any edge on channel 0
TIE =   1;                     // timer interupt enable

EnableInterrupts;


while(1){

    if(flag==1){

    sprintf(string,"%16d",debug);
    writeLine(string, 1); //write to screen
    flag=0;

    }
    if(flag2==1){

    sprintf(string,"%16d",debug2);
    writeLine(string, 1); //write to screen
    flag2=0;

    }

    if(flag3==1){

    sprintf(string,"%16d",debug3);
    writeLine(string, 1);

    flag3=0;

    }

    sum = sum + diff ;


    if (cnt>10){

      //avg = (float) (sum) / (float) (cnt);
      avg = sum/cnt;
      cnt = 0;
      sum = 0;

      sprintf(string,"%16lu",diff);
      writeLine(string, 2); //write to screen
      flag2=0;
    }
}

}

__interrupt void RealTimeInterrupt( void )
{
CRGFLG = 0x80;       /* clear rti flag */
}

__interrupt void TC0Interrupt( void )
{

TFLG1 = 0x01;     //clear TC0 flag

if(PTIT & 0x01){

    rise = TC0;
    flag = 1;
} else

{

    fall = TC0;
    diff = fall - rise;

    fall=0;
    rise=0;

    cnt++ ;

    flag = 0;
    flag2 = 1;


   }

}

__interrupt void TOI( void )
{

    flag2=0;
    flag3 = 1;

}