On Tue, 10 Jun 2014, Grant wrote:
> >> Understood. Can you tell me how to disable VBUS on the USB
> >> hub/controller? I'll be attempting this on a Beaglebone.
> >
> > I don't know what controller the Beaglebone uses. In general, however,
> > it isn't possible to disable Vbus on a USB host port and still use the
> > port. To do what you want, you would have to physically cut the Vbus
> > wire in the USB cable and splice the device side of that wire to the
> > external power supply.
>
> USB cables like that do exist for sale. Is there a way to disable
> VBUS on the host port if I use a cable like that?
Like I said before, if you did manage to disable Vbus on the host port,
the port would be unusable -- even with a separate power source for the
device.
The hardware in some controllers will allow port power to be switched
off and the hardware in others won't. I don't know whether the
Beaglebone's controller does. For the ones that do, probably the
easiest way to turn off the power is to use my hubpower program:
http://marc.info/?l=linux-usb&m=127162615232234&w=2
Alan Stern
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
