Hi all,
I am trying to debug some code I have written and I can't seem to =
understand why it is not working. The code builds fine, and I have =
tested it on hardware, and in the simulator.

I have included the code below (sorry about the size of it, didn't want =
to leave out anything important!)

The problem is if I output a character using putch(char) such as the =
line directly after main()
"putch(success+1);" and I step through using the simulator the program =
seems to get stuck on the "while(1)" instruction and never seems to get =
to the "if (encoder_count =3D=3D 50)"....

If I comment out this first putch and change nothing else, the program =
runs all the way through. I am getting consistant results from both the =
simulator and hardware.

Has anyone got any ideas? I am totally lost here as I don't see why =
having that one putch line should cause the program not to work!

Thanks for any help.
kind regards,
James Fitzsimons





/**********************************************************************
 *
 * Filename:    encoder.c
 *=20
 * Description: Counts interrupts on portb from attached motor encoder.=20
 *     Every 50 clicks the PIC sends a message to the serial port.
 *   =20
 *
 * Notes:       The constants in this file are specific to PIC 16F84=20
 *    hardware.
 *
 * Written by James Fitzsimons for PIC hardware
 * 13/12/01
 *
 *
 **********************************************************************/

#include <pic.h>
__CONFIG(UNPROTECT);    // Cofiguration fuses XT|WDT off|PWT off|code =
protect off
#include "delay.h"

void toggleLed();
void putch(char);
char getch(void);
void DelayMS(unsigned char);


/**********************************************************************
 *
 * Function:    main()
 *
 * Description: When the encoder count variable reaches 50 the PIC
 *    sends a message to the PC.
 *=20
 * Notes:       An encoder is attached to portb. The code utilitses=20
 *    the interrupt on change functionality of the portb.
 *
 * Returns:     This routine contains an infinite loop.
 *
 **********************************************************************/

unsigned int encoder_count =3D 0;
char success =3D 65;
unsigned char temp;

void
main(void)
{
 // test to see that serial coms is up
 putch(success+1);=20

 //enable interrupts
 GIE =3D 1;

 // enable RB port change interrupt
 RBIE =3D 1;
=20
 // clear the interrupt flag if set
 RBIF =3D 0;

 // setup RB7 as input
 TRISB7 =3D 1;

 // setup rest of portb as ouputs so as not to cause interrupts
 TRISB6 =3D 0;
 TRISB5 =3D 0;
 TRISB4 =3D 0;

 // setup RA1 as output
 TRISA1 =3D 0;=20

    // endless loop counting interrupts on pin 7 of portb
    while(1)
    {
  // wait for interrupt
  if (encoder_count =3D=3D 50)
   {
    // send charater 'A' to terminal
    // disable interrupts so that timing for serial i/o isn't stuffed up
    GIE =3D 0;
    putch(success);

    // reset encoder_count
    encoder_count =3D 0;
 =20
    // finished sending char so re-enable interrupts
    GIE =3D 1;
   }
 }

}   /* main() */



/**************************
*
* Interrupt Service Routine
*
**************************/

interrupt void
isr(void)
{
=20
 // check to see if interrupt on change flag set
    if ( RBIE && RBIF )
 {
  // read portb
  temp =3D PORTB;

  // increment counter by one
  encoder_count =3D encoder_count + 1;

  // clear interrupt flag
  RBIF =3D 0;

  // toggle led to show in isr
  toggleLed();
 }
}

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