On Sun, Dec 7, 2008 at 8:20 PM, Bob Ammerman <rammerman@verizon.net> wrote:
> Again, you do *not* actually need to use an interrupt handler, nor globally
> enable interrupts to get interrupt-on-change to work to wake up from sleep.
>
> As Olin noted, an enabled interrupt-on-change causes an interrupt
> *condition*, but it only becomes an actual interrupt if interrupts are
> globally enabled.
>
> So, you want to do the following:
>
> 1: Make sure you properly initialize your inputs as digital as opposed to
> analog (often controlled by a port called ANSEL, but this varies amoung
> several different PICs).
>
> 2: Make sure your inputs are set up as inputs rather than outputs (this is
> the default condition, check out TRIS registers for this).
>
> 3: Make sure that interrupts are globally disabled (often a flag bit called
> GIE). This is the default condition.
>
> 4: Make sure the interrupt-on-change interrupt is enabled (another flag
> bit).
>
> Now a SLEEP should be terminated when the input bit changes, but no
> interrupt handler is needed.
>
>
> Some baby steps:
>
> I would start by trying to write a program that just copied the state of an
> input bit to an output bit. This makes sure you have inputs set up as inputs
> and outputs as outputs. Then I would try to add the
> interrupt-on-change/wakeup from SLEEP logic.
>
> -- Bob Ammerman

Very helpful, thank you. Attempting now.



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