alt Hacker News> The linked article appears to be doing a quarter-VGA display in 3-bit/8-color, and is sort of right at the limit of the power of the engine.
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.
> it turns out that there are a lot of situations where PIO can avoid the need for an application-specific peripheral
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.