It works in exactly the same way as my DIY stackmat display. You can find the documentation for that here: https://jayanth-rajakumar.github.io/ledmat
The schematic for this is here: https://jayanth-rajakumar.github.io/btmat
Not yet, but I'll try to test it on as many timers as possible when I go to a comp in a couple of weeks.
I've tried it on a QJ and Gen4 so far, and it was actually quite a pain to get it to work on both. I think if it has to come to that, I'll add some kind of hardware switch to select the...
Depending on what you already have, this should cost around $15-20 to make.
I wrote up a long article describing how to put everything together, and it includes a 16-minute video tutorial. It also contains some interesting technical background. Check it out here...