Hi John,

1st of all, if the ONLY interrupt u need enabled is RB0 then

INTCON = 90; //enables global and RB0 interrupts

2ndly, ur interrupt routine should be set up this way:

static void interrupt isr(void){
 //RB0 interrupt
 if (INTF){
    // do something
    INTF=0; //clear RB0 interrupt flag
 }
}

FYI, u can only have one interrupt routine which means all ur interrupts should be
handled within that one routine! so for example if u needed to have TMR0 interrupt
enabled as well as RB0, then the above interrupt routine would look like this:

static void interrupt isr(void){

 //TMR0 interrupt
 if (T0IF){
  // do something
  T0IF=0; //clear TMR0 interrupt flag
 }

 // RB0 interrupt
 if (INTF){
    // do something
    INTF=0; //clear RB0 interrupt flag
 }
}

hope this helps. BTW, if u needed to have TMR0 interrupt enabled, then u would need
to set the value in the OPTION register appropriately. this might be a good time to
have a look at the datasheet for the PIC in use.

seyi


"J.A.YOUNG" wrote:

> Thanks very much to all for the array size stuff, I'm using the bit array to
> store my potentials and wall data, so cutting down on memory, but will put in
> my project that another type of chip would be more appropriate.
>
> <using HiTech PICC-LITE under MPLAB for a PIC16F84A>
>
> For the current pic i'm going to use the dead simple 'follow-the-left-hand-
> wall' technique. I've written the basic code, but at the moment its a case
> of "move 1 square, stop. read sensors. go again", so I'm trying to setup an
> interrupt on RB0 so that when the Left-Hand Sensor changes, I can jump to the
> decision code.
>
> As yet my program runs and compiles but doesn't do anything on a change to B0.
> I've kind of pieced the code I need together from the PICCLITE manual and other
> tutorials, and can see there's stuff about option registers, but nothing I've
> tried has made a difference. Code to try out the interrupt is below.
>
> void interrupt sensor()
> {
>         int i;
>         PORTA=255;
>         for (i=40;i--;) continue;
> }
>
> main()
> {
>         TRISA=0;
>         TRISB=3;
>
>         //OPTION=192;        tried fiddling with this code but I'm just
>         //INTCON|=(1<<GIE);             guessing really...
>
>         for (;;)
>         {
>         PORTA=0;
>         }
> }
>
> Simple stuff no doubt, but any ideas??? cheers,
> john
>
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