another way to get a keyboard matrix to work off 1 adc pin

[Heckler]

This keypad is not a "matrix" but rather 12-13 individual pushbuttons but you might gane something here...

Here are a couple of videos I ran across a while back where this guy uses a similar method to read a keypad using just one pin.

Great nostalgia if you were around in the mid 70's and remember phone phreaking.
Especially if you dig deeper on the projectMF web site they have some old recordings of guys phreaking(hacking) the telephone network to make free long distance calls.

If you are say only in your 20's now you might say "What is long distance??"






And if you follow this link you will find the code and schematics of his project

http://www.projectmf.org/