We had a bounce problem with a 4x4 keypad.  Well, not really a problem,
more facing real life.  When you take your finger off a button, it doesn't
go from down to up cleanly very often, sort of flutters.  Once you detect a
key, you wait for it to show 'up' for 'x' successive readings.  We'd use
interrupts to catch the key going down, and disable them until the key was
solidly back up.  During time critical activities in other areas, we'd
disable the keypad.  Sort of thing you have to think about with unclean
inputs.

  <edtodd@sni.net>    Ed Todd