William Chops" Westfield" wrote:
> does IoC configured on a port cause the PIC to
> wake up from sleep even if higher levels of interrupt control aren't
> enabled?

Yes.

> Some CPUs return to sleep mode when they're done executing the ISR,

Maybe, but not PICs.  PICs have no notion of being "in" a interrupt.  A
interrupt is simply a event that occurs when its requisite conditions have
been met.  If interrupts are globally enabled, the specific interrupt is
enabled, peripheral interrupts are enabled if this is a "peripheral"
interrupt, and the interrupt condition becomes true, then the PIC will
execute a call to the interrupt vector while at the same time disabling
interrupts.  That's all.  If you happen to have code at the interrupt vector
that services the interrupt and then returns to the interrupted code, that's
your business.  You might call that code a Interrupt Service Routine or ISR,
but the PIC doesn't require nor expect nor check for that.

In one PIC 16 project I used the INT interrupt as a externally forced GOTO
4.  Yes, this caused the stack to overflow and wrap around, but I didn't
care since the code never tried to return to the address pushed onto the
call stack by the interrupt.


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