re: Keypad Interface

   Henry, depending on your application, you might look at
an alternative keypad interface using the 74C922 keypad
decoder chip. Normally I try to eliminate as much `glue'
logic as possible when using the PIC but the 74C922 is
easy to interface and takes care of scan rates and
key-bounce. You are looking at 4 data lines, 1 !CS line,
1 Data Available line, and 2 capacitors. I'm working on
a 16C74-based weather station and I had to implement an
external data bus with an external chip-select decoder, to
communicate with a variety of peripheral chips in both
serial and parallel format. In your case, with a 16C84,
you can easily decode the keyboard directly but using
an external keyboard decoder can reduce your I/O lines
as well as software.

   - Tom

At 11:23 PM 4/3/97 -0600, you wrote:
>been doing basic i/o with 16f84 " if input do output "
>but i now need to be able to scan a 4 x 4 keypad and get
>1 and 2 key inputs from it. Any suggestions or pointers
>would be greatly appreciated.
>
>Henry dragon@topher.net
>
>