>> 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,

Attached is a chunk of code to do just that.  To simplify things, I require
that "double" keypresses have a common line, although one could easily
change by shifting bits around a little (rlf/rrf).

I think you can probably figure out how to detect 3-down keypresses too,
iuf you look at the pins on the rows/columns other than the "active" one.

The enclosed module is intended to be called at about 60 Hz.

In series with each pin used in the matrix is a 150 ohm resistor.  VERY
important.  Diodes, etc. are not needed.

Andy

Attachment converted: wonderland:keyscan.src (TEXT/CSOm) (0000D8C5)

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Andy Kunz - Montana Design - 409 S 6th St - Phillipsburg, NJ 08865
          Hardware & Software for Industry & R/C Hobbies
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