USB Host Mode Adapter

Rob Williams rob at
Thu Jul 3 17:59:13 CEST 2008

Hi All,

I'm not an OpenMoko guy by any stretch, but definitely a big supporter 
of open source markets and neat devices like the FreeRunner. Anyways, 
not sure exactly how things work on the OpenMoko hardware, but over on 
the Nokia Internet Tablet (the N800) we had a similiar problem in that 
the hardware supported USB OTG hostmode, but that since the tablets had 
a MiniB and the OTG standard says that's a big no-no we had to come up 
with our own solution. I did some reading on the power injection that 
was required for the Neo, but it sounds like this has been solved on the 
FreeRunner in the same way the Nokia's do it; have the equipment provide 
a limited amount of power over the USB bus when placed into host mode.

On the Nokias you can engage host mode by having the ID pin of the 
mini-B shorted to ground as per the USB OTG specs; I'm not sure if this 
is true for the FreeRunner hardware, but if it is you may be very 
interested in the solution we came up with:

Right now I still build and test each of these by hand, but I'm getting 
manufacturing lined up soon as it's become an extremely popular item 
(I've sold over 500 so far). Anyways, if anyone reads this and is 
interested or thinks it might work for the OpenMoko offerings let me know!


Rob Williams
Open Source Enthusiast
Electronic Product Online Ltd

More information about the hardware mailing list