PRU DMA example w/ HUB75 matrix dithering

Hey BeagleBone hackers,

Since I couldn’t find any modern RemoteProc-friendly examples using PRU and DMA, I put together one and thought I’d share. I figure by the time I finish what I’m working on, it won’t make a good example. Also it’s not quite 100% and maybe a few more eyeballs will help!

As it stands, the code is using a single-shot DMA transfer repeatedly instead of using a continuous DMA transfer loop–also it’s using a large transfer which I suspect is responsible for some of the system instability-- those are my TODOs.