Designing for User Feedback
Whilst you will have chosen the tactile feedback keypad, to maximise touch feedback, you may still be looking for other ways of telling
the user that the key has been actuated.
There are no hard and fast rules, however, you can of course integrate an LED into the key to indicate that it has been pushed.
However, you may well want to add an audio route to feed back this information. This will normally need to be designed into your software
and hardware. The form that this takes is of course dependant on the application, and environment into which it is going.