The resolution and color depth restrictions were the product of the low data rate of USB FS (~12 Mbps), not inherent limitations of PIO.
> It's... honestly it's just really weird. And IMHO has really, really, REALLY limited application.
I'd agree with "weird". But it's useful weird; it turns out that there are a lot of situations where PIO can avoid the need for an application-specific peripheral, and can provide that function in a more flexible fashion than a fixed-function peripheral could. Dmitry's SDIO device emulator is a great example - almost every other SDIO peripheral on the market is host-only.
And I can only repeat: I think that's an aspirational delusion. I'm not aware of anyone shipping a PIO solution to anyone in volume. It's "useful weird" to Hackerspace nerds like us, and that leads to some epistemological skew.
Hardware needs to be boring and reliably supported (by people you can sue!) or else no one will bet a 10k unit PCB run on it. This is anything but.
>Basically PIO smells like a wart to me. I genuinely don't know who wants it. Regular hackers aren't sophisticated enough to use it productively and the snobby nerds have better options.
driving complex displays with no spu use: https://dmitry.gr/?r=06.%20Thoughts&proj=09.ComplexPioMachin... (my work)
pretending to be memory stick and sd card at dozens of mhz as a slave to a sync bus (my work)
ethernet: https://github.com/kingyoPiyo/Pico-10BASE-T (not my work)
68k bus slave (my work)
usb host https://github.com/sekigon-gonnoc/Pico-PIO-USB (not my work)
all on a $1 chip
Please don't.
I mean, I applaud your work. But let's also be honest (in the "tough love" sense): those are all toys with significant limitations that preclude anyone shipping any of them on an actual device to an actual consumer. I mean, your SOC (maybe a $2 one) surely already includes a SPI master and USB host!
Actual interconnects that solve real market problems have big boring spec books and competing implementations and silicon vendors. The application for PIO is basically limited to "I have to connect to this crazy old junk and no one makes the part I'd otherwise need".