Josh Koffman wrote:
> At the start of my ISR, I save WREG, STATUS, and BSR (this is a
> PIC18F) to temporary registers. I then restore them on exit. I've been
> tracking a bug that seems to be manifesting itself due to incorrect
> bank selection. Here's why I think this is happening, look at the
> addresses of the following registers:
>
> W_Temp     0x080
> PORTA       0xF80
>
> The other registers have similar overlapping low byte addresses.
> So...going into my ISR I might not be in the correct bank. But if I
> change the bank, I've upset the current state and things won't get
> restored correctly.
>
> I'm not really sure what to do on this one.

There is a lot I could say about banking on PICs, but I won't under the
current conditions.  However, there is code freely available on my web site
that solves exactly this issue.

> I suppose I could use a
> lot of banksel commands (and that's likely what I'm going to try while
> waiting to see what everyone else thinks), but is there a better way?

Absolutely, especially considering that this way won't work.


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