Keyboard Circuit Board Diagram : symlink.dk - C64 USB Keyboard : From the diagram above, you can see that the combination of row 2 and column 2 could only mean that the follow the diagrams below to connect the keypad to an arduino uno, depending on whether you have a 3x4 or $300 for a special keyboard encoder capable of doing this is completely off the board.

Keyboard Circuit Board Diagram : symlink.dk - C64 USB Keyboard : From the …