> Van: Rigby-Jones, Michael [PAI01:4837:EXCH]
<michael.rigby-jones.mrjones@NORTEL.CO.UK>
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: Re: Keypad Decoding ][][
> Datum: maandag 4 januari 1999 11:49
>
> Have a look at http://home.clara.net/mikerj/keypad.html for a possible
> method of interfacing a 3x4 (or 4x4 with modifications) to a PIC using
only
> 4 pins.

It's even possible to go upto 28 buttons with only four lines ...  The
Down-side is that any _combination_ of buttons is received like another,
legal, button.

( All connected with diodes : One line is the Pull-down. 3 buttons
connected to a single line.  3 buttons connected to two lines.  1 button
connected to 3 lines.  That gives 7 buttons on 3+1 lines)

Greetz,
  Rudy Wieser