German wrote:

> I have a hex keypad with 16 pins (one for each key) and 1 common.
> Can I use this type of keypad in a project that requires a 4x4 matrix
> keypad (8 lines/pins)(row/column selection)?

  Yes, but you aren't going to like the answer!  You'll need four 4066
chips and two octal SIL resistor packs for pull-downs.  Each key and
pull-down controls one "switch" which makes the matching matrix closure.

  This *is* very useful if you need for example, to control a remote
control (IR) sender to control some device for four functions, and there
is a cute trick using a pocket calculator as a dirt-cheap item counter.

  The message for your application however is - you need a matrix
keyboard and they are usually inexpensive and common.  Note that some
keyboards (real old Touch-Tone telephone pads) have a common with rows
and columns.  In that case of course, you don't need to use the common
and it would do the job.
--
  Cheers,
        Paul B.