How does a PSP game interface with USB

[ASMO.]

For example, a camera for skype.

This is a programmer level question for homebrew.

[[Unknown]]

I don't know the details exactly - but generally, it uses the sceUsb* APIs.

I'd suggest looking at examples of that usage, e.g.:

http://lukasz.dk/mirror/forums.ps2dev.or...tml?t=9523
http://wololo.net/talk/viewtopic.php?t=4891

Specific to the camera, I think someone was messing with camera support in PPSSPP recently, so I'd suggest looking at that:

https://github.com/hrydgard/ppsspp/pull/11305

-[Unknown]