Raymond,

You can use parallel-in/serial-out shift registers. Cascading them
you can get as many input lines as you need (as far as speed is not a
constraint in your application).

I used them for keypad interfacing. Easy and cheap ! You can find the
details in my web page : www.ilari.org (have a look at the terminal page).

Have fun !

Joan

 Raymond Choat wrote :
>
>  My project is using a 16F877. I need to hook 12 switches/buttons to it.
>  These switches/buttons are 4 ft away. I have 4 pins on the
>  16F877 that are
>  still not used. Would it be best to use a multiplexer chip or
>  IC2 to another
>  Pic reading the switches and buttons. Will a multiplexer allow
>  more than one
>  switch to be pressed at the same time? Has anyone done this that has
>  examples?
>  Many Thanks
>

--------------------------------------------------------------
     Joan Ilari                 e-mail : joan@ilari.org
     Barcelona                   www   : www.ilari.org
     Spain                      Voice  : +34 93 431 96 39

"I've seen things you people wouldn't believe. Attack ships on
 fire off the shoulder of Orion. I watched C-beams glitter in
 the dark near the Tannhauser gate. All those moments will be
 lost in time, like tears in rain. Time to die..."
                                               -Blade Runner-
---------------------------------------------------------------

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