[i336_]

After staring at that repo for a bit (my understanding of C is minimal, and I've never done any embedded work although I definitely want to) I finally got the "OH, the six set_pin() calls are R, G, B for two sets of rows on two panels" (in clock_two_rows()) it kinda clicked and made sense.

I'm not 100% on what "line selectx4" does though. And this is all much more foreign than I'd like... but that's fine, I'll figure it out eventually. (The main thing with software is that accidents/learning/experimentation don't cost anything :P)

It would be interesting to get a microcontroller, or set of microcontrollers connected together at very high speed, to clock data out to the panel in perfect lockstep. An excuse to use assembly language perhaps, but only if the driver microcontroller itself is deterministic (a bit of an unknown).

I'm surprised about the bit with the magnets (I guess if you're trying to bolt a computer with a spinning HDD onto the back of it you're doing it wrong).

Good to know the LEDs turn off instantly. Thanks very much for that bit. I do wonder about the board-to-board propagation time, yeah. I take it each board is chained to the next board's enable line (?), or are they all driven from the microcontroller?

[ChuckMcM]

You don't need assembly, you just need a common "sync" line where all the computers start at a given point.

[i336_]

Right. That makes sense.

I haven't fully mentally appropriated how far embedded computing has come. I would have solved this by counting instruction lengths :)