As a continuing discussion of what plagues a seemingly easy interrupt:

> >might
> be a victim of read-modify-write feature. In this case, it may be
> > > necessary
> > > to use a 'shadow' register.

> > Should I Switch my pin toggling to another PORT? I have port C open right
> > now....I currently have portb.0 as the frequency output pin, with portb.2
> > to my LCD.
> I think it could be a good idea. If you run out of pins later (like
> always!),
Tried this alone. Did not help.

> use a shadow register. What you do, is you change the bit you want to
> toggle
> in the shadow, and then write the shadow to the port. If you want to
> read a
> pin, you read the port pin directly. A read-modify-write problem is the
> hardest type of problem to solve without an ICE.
Ok, here is what I can do in my ISR:
(using a shadow register, to toggle a pin via Compare Mode interrupt):
        btfss   portb,0 ;Bit test the PortB.0 for a set condition,else:
        goto    Set_Pin
        bcf     Pinstate,0 ;Clear a SHADOW bit, in register Pinstate,bit0
        goto    End_ISR
Set_Pin
        bsf     Pinstate,0
End_ISr
        ;somehow load the Portb(pin0) with the bit0 from Pinstate
register.

Am I on the right track?
So far, I beleive with this short code, PCLATH would be corrupted, as
a GOTO statement is used in this ISR.  Is this correct?  At what point is
FSR changed in any way?

-Dave