Paul pretty much summarizes everything in his reply to this.  He does a
great job.

Most of my applications do something on keypress, then sleep, so I use the
PORTB interrupt.  If your PIC is on constantly, polling is the better
solution.  I agree with pretty much everything Paul states, except that
using an interrupt is undesirable.  Many applications "do something on
keypress", so using a PORTB interrupt to start a debounce timer, and
another interrupt when debounce complete, is a very convenient method for a
lot of applications.  I usually am tight on RAM, so using none at all for
my keypad code (except for hardware flags) is rather convenient.

----------
> From: David Olson <dolson@PROGRESS.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Newbie Toggle Switch Woes
> Date: Tuesday, April 13, 1999 10:55 AM
>
> Justin,
>
> I know your mention of hardware is actually for the switch to generate an
> interrupt but, would you consider a NAND gate latch setup? Or is this too
> much or unnecessary hardware? I've build a sample circuit like this
before
> but I've never tested its resiliency with a range of switches that have
> varying debounce times. Any information I've gathered from this approach
has
> not pointed to this being a "better" solution.
>
> Unfortunately, I need this to be as robust as possible and with the
solution
> being through software, I could at least "tune" the debounce if switches
are
> chosen outside a comfortable range.
>
> I'm in the investigation phase right now and I'm using some simple SPST,
> normally open, momentary switches - I will ultimately move this to a
setup
> that is rubber keypad/PCB contact assembly, for which I really appreciate
> the note from Paul Webster on switch/key design - that was great.
>
--SNIP