Paul__B:
dc42:
If it's a 4x4 keypad, then you don't need all 8 ways of the 4051, you only need 4 ways. So you only need to drive 2 of the select lines of each 4051. Plus one of the inhibit pins (or both connected together) so that you also have the state of no key pressed. So you only need 5 Arduino pins in total.He did spec a 4 by 8 matrix - not the earlier system described in the video above.
OK, so 6 pins needed then (3 for one 4051, 2 for the other, and one common inhibit) - assuming he needs to simulate pressing all 32 keys.