Let's not fall into the trap of arguing with the O/P over his implementation. While I generally object to an inquiry asking for code, when there are examples accessible via search, on this forum, that addresses his query, I also dislike it when we're trying to change his implementation rather than answering his questions.

Now, it's certainly not our place to criticize applications published elsewhere, regardless of how poor they may be. However, but I have to agree, it's pretty silly to use a microcontroller to interface to a keypad encoder chip that costs more than the microcontroller.

Maybe the O/P can clarify why it is that he'd rather use the reather costly 74C922 rather than encoding the keypad with firmware, which would cost him essentially nothing, and for which code is already published. Maybe there's a pin shortage, or some other compelling reason why he should do that, but it makes little sense unless he's building a one-of, in which case it matters not at all.

I think we should know why he's made the choices he's made, if he can tell us, and try to support his goals rather than trying to change them. If he's made some incorrect choices, it will become apparent to him. Don't you agree?

RE