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On Wed, 2010-03-17 at 02:42 -0700, Don Quixote de la Mancha wrote:
> On Wed, Mar 17, 2010 at 2:28 AM, Kari Somby <[email protected]> wrote:
> > It can be something on your USB device or USB port.
> 
> To clarify, your motherboard may not be applying device power to your
> USB ports.  I don't think USB power is actually required by the
> protocol spec, rather its an optional feature.  Even if power is
> provided, the amount provided may be insufficient for your particular
> device.
> 
> > When using USB purely powering purposes, no drivers are needed - only thing is
> > that USB devices are enabled.
> 
> That's usually the case, but its not true in general.  To charge a
> Motorola RAZR from USB, one needs special software.  There are several
> freeware packages that enable RAZR charging.  I only tried on Mac OS
> X; I don't know whether there is a Linux package that does it.
> 
> Don Quixote
> -- 
> Don Quixote de la Mancha
> [email protected]
> http://www.dulcineatech.com
> 
>    Dulcinea Technologies Corporation: Software of Elegance and Beauty.
Actually the USB port will limit to 100ma if the software on the device
doesn't complete negotiation with the port software, and the system can
shut down the power, depending on the systems power requirements.  You
can get a copy of the spec on line if you want, at:

http://www.usb.org/developers

	You might also want to read carefully the part about USB-To-Go, which
applies to portable devices implementing the USB protocol and which may
require each device on the bus to supply its own power, due to the
design constraints of battery power.

Regards,
Les H



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