So I was planning a project, when the arduino I was using ran out of pins. I had no multiplexer laying around. Nor had I any other ready made solutions. But when I browsed my "chip collection", I found a handful of 4017 decade counters. I used them in a step sequencer together with a 555 as clock, when I build a drone synth some time ago.

I thought: If I timed the clock signal, maybe I could send the outputs of the counter through the switches in the project, and as long as they where used as pull down, it might work.There's probably more drawbacks than I can imagine, but it worked for the user input buttons that I needed.

Demo:


Source code and diagram of the demo in the video can be found on the linked github page.The sequencer which spawned this idea was inspired by Aaron and his project at: