First: Sorry to those c.a.e folks who abhor s.e.d -- hopefully the politics won't bleed onto this thread.
On to the real question. It's phrased oddly, but I think it gets to the point best:
If I have a dingus with a battery in it, and I want to charge that battery via USB, and I want to get the most out of the USB port, does that dingus have to have a microprocessor in it that talks on the USB?
OR, can I determine how much current I can draw via USB with some purely analog arrangement of circuitry on the "battery charge" side.
I think I know the answer, but I'd like to be surprised.