ubuntu-phone team mailing list archive

[Ed Kapitein <ed@xxxxxxxxxxxx>]

On 9/12/2015 3:10 PM, Stephen M. Webb wrote:
> On 15-09-12 08:11 AM, Ed Kapitein wrote:
> > Hi,
> > i want to use a raspberry pi to charge the BQ 4.5, without a (powered) hub.
> > The BQ is not charging when i plug it into the pi, and the pi never enumerates the BQ on its usb bus.
> Sounds like they're both OTG connections, each waiting for the other to assert host mode.
>
> It's possible neither device has a kernel that supports host mode on the OTG port:  you can check on the devices using
> the command line 'grep CONFIG_USB_OTG /boot/config-$(uname -r)'.  In particular, this is required on the Pi, which has a
> USB Standard-A connector so needs to play the host.
>
> It's also very possible you're using a regular USB cable and not an OTG cable, so host-slave nego never happens and
> they're both waiting in slave mode for the other device to assert dominance through hardware signalling.  See the
> Wikipedia entry https://en.wikipedia.org/wiki/USB_On-The-Go for a detaied description.
>
> --
> Stephen M. Webb  <stephen.webb@xxxxxxxxxxxxx>
Hi Stephen,

Thanks for your toughts. The BQ does charge from a host that has 
CONFIG_USB_OTG=N and with an ordinary micro USB cable.
Just to be sure i used a OTG cable, but that did not work with the pi.
Any idea if/how you can force either device into slave mode?

Kind regards,
Ed