I've been working on a couple new designs recently to enable more keys for a given number of microcontroller pins. I've tried using the Japanese Duplex Matrix (talked about on
https://kbd.news/The-Japanese-duplex-matrix-1391.html) as well as a design using a demultiplexer for the columns. I've been breadboarding these versions to test them out, where I write and flash firmware onto a pro micro and build a smaller version of the matrix on a board and then validate that everything is working as expected (it's not always
)
This is time consuming but mostly an accurate way of doing this, but I wonder if there are better ways? Does anyone do this fully in software through simulating the circuit and also the controller to see what works and identify issues? Would be great to understand other workflows in the hope of improving my own!