Amperage through built in usb?

"CaliberMengsk" wrote:
Hey guys, I'm at work, so I can't check, but I had an idea pop in my head, and I'd like to know if the USB port (when wall adapter is plugged in and such) is limited to the standard 100-150ma output of a normal usb port, or if it's higher because of the wall wart?

(Idea has to deal with having a dynamic temperature system for use with the rift, and would require a fan as well as a thermoelectric {Peltier} cooler, both of which require a fair amount of amperage. I don't have either on hand, so I can't test anything anyway, but the idea is bumping around, and it'd be cool to have it all work with just the usb cable of the rift.)

Its 500ma for usb2.0 and 900ma for usb3.0.
Technichally your supposed to negotiate with the host if you want more than 100/150ma but thats just a courtesy if you will.
If your a good boy you design your device to ask for more current and if the host says no you do not draw it.
Lots of USB devices dont even bother negotiating for higher current.

Theres absolutley nothing stopping me from drawing 500ma from one of my ports with a dummy load.
The only current limiting device fitted will be a polyfuse.

With all that said I recall reading that the reason people cant plug there Leap Motions directly into the DK2
port is that Oculus lowered the max current allowed by negotiation with one of the firmware updates(the Leap is obviously properly designed and requests the current rarther than just taking it).

Unfortunatley I dont know what that limit is and would assume that they lowered it for a good reason.