USB host successes

[Joel Newkirk]

On Tue, 9 Sep 2008 18:23:43 +0200, Maciej Delmanowski <harnir at harnir.net>
wrote:
> On Aug 25, Joel Newkirk wrote:
>> probably still useful - the question is really whether the Freerunner
> can
>> power a hub and two adapters)
> 
> I've thought about different idea - can FreeRunner be powered from USB
> power
> adaper connected to the USB hub? Like this:
> 
> 
>       Power plug
>           |
>           |
>        USB Hub---Ethernet, thumb drive, other devices
>           |
>           |
>      FreeRunner
> 
> That would probably solved power requirements... But it's still 220V (or
> 110V)
> attached indirectly to the USB network, is it safe ('cause I have no
> idea...)?
> For example, can I connect another computer through USB or Ethernet card
> with
> that configuration?
> 
> harnir

[NOTE: It's NOT - or better not be - 220V or 110V direct to the hub, it's
likely to be 5Vdc]

You should be able to do this with the Freerunner, but you have to set the
mode in sysfs correctly, AND you should have 15k resistors between the D+
and D- data lines and ground. (see
http://wiki.openmoko.org/wiki/GTA02_sysfs#USB_Host_.2F_Device)  I'd ordered
a combo USB hub plus card reader that I wanted to try to utilize this way,
but when it arrived the hub was intermittent and the card reader was dead,
so I've not been able to try yet. (awaiting RMA)  I've got a 5V 2A cord
from my lost Zaurus that I was going to power it all with, figured that'd
be adequate to charge the freerunner at 1000mA while powering the hub/card
reader and whatever I've plugged into it.  Just needs a bit of rewiring
inside the hub.

As far as connecting a desktop PC and the Freerunner to the hub at the same
time, I'm not sure WHAT would happen if the Freerunner were in Host mode -
you'd get contention as to which was master of the bus, probably neither
would be able to work in that configuration. (I'm not even sure if the
design of a USB hub would allow it - I think it treats the 'peripheral'
connections differently than the 'host' connection, even apart from
expecting power to be present on the host port)

j