koen at dominion.kabel.utwente.nl
Sat Jan 20 13:21:41 CET 2007
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Nikita V. Youshchenko schreef:
>>> How can it charge over USB if it gets full discharged?
>>> AFAIK, USB device is not powered by USB host until it is configured.
>>> So gadged must be operational to charge over usb.
>> Well, I'm almost certain that my USB mouse has no battery builtin, so
>> I guess USB does provide some minimal power to enable configuration.
> That depends on how usb client hardware is done.
> In your mouse, there is microcontroller that controls usb client
> functionality, and powers itself from usb (yes usb gives some limited
> power - up to 100 mA if I remember correctly - even to client which is not
> configured yet.
> But in case when USB is controlled by Linux USB Gadget driver, central CPU
> must be operational and kernel up and running for USB client functionality
> to work.
Or using the bootloader, or a seperate PMU or ...
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