Thank you for the project :)

[cutephoton]

I mostly wanted to thank you for posting this & the video. Thinking in the current domain like this is like trying to write with my left hand. I don't have the muscle memory nor intuition to use it. I design hardware as a hobbyist, but professionally I am a (bored) embedded systems engineer. As I come from a digital domain, discreet analog circuits tend to be more challenging.

This is exactly the kind of project that makes trying something different fun and educational. It was simple, easy to understand, practical, and (bonus) firmware is simplified. Current mirrors tend to be discussed in more formal ways with lots of text, equations and toy circuits that do nothing useful... it's so much easier to appreciate when the application is real. I hope to see more from you in the future. :) Thank you.

And so behold... this is an unintentionally small 4x4 single sided keypad test fixture. I'm thinking of adopting this technique in a project that uses low pin count (8 pin) ATTiny devices to handle user input and WS2812-style RGB leds. I mostly wanted something I can just drop in to other projects instead of re-implementing these basic building blocks every time I design something.

[sgmne]

Looks like a nice layout. Thanks for sharing! With one pin for keypad and 5 pins for up to 20 LEDs using Charlieplexing something quite spectacular can be made. Have fun!