>>
> Are you sure you can do this? if you are using a readymade matrix keypad
> it will probablly be wired as a matrix that needs to be scanned.

It's not a readymade keypad. I have control over each button.

>> I've never interfaced anything to the PGD/PGC lines, should I put a
>> 10K (100K?) resistor in series with the pin, then go to the
>> pulldown/switch (see:
>> http://img.photobucket.com/albums/v55/goldscott/pgd-pgc-question.png)?
>>
> 10K should be enough to allow in circuit programing. Note that if using
> an ICD2 it doesn't like it's programming pins pulled up so make sure you
> arrange your pullups and pulldowns so they pull the line low rather than
> high when no buttons are pressed.

I'm using a PicKit2. I read about ICSP programmers not liking pullups,
so that's why I went with the pulldowns.

>> What are some ways to go about this while keeping power low? I know I
>> can poll each button until I find one high, but the processor will
>> always be at full power doing this. What about using a simple logic
>> gate to OR/NOR all the switches together to an interrupt pin to wake
>> the processor up?
>>
> It's certainly an option, another option is to have the pic wake up on a
> timer (say once a millisecond), read the keys and then go back to sleep.

I like that suggestion! I didn't consider that, but that seems like a
good route to go.

>> What other suggestions do you have, and what issues might I run into?
>>
> As well as the above you may need to consider debouncing in some way.

Of course the buttons will be debounced. What's a common debounce
period, 10ms? 50ms?

Thanks,
Scott Larson

As you can tell, I'm a noob. I finished college a year ago and I've
been writing embedded software for work, but projects like this I get
to do at home in my spare time. I like that I get to do everything
from hardware/software design to PCB layout to soldering the
components on. Having your own project come to fruition is quite a
thrill.
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