Hi Bill,

Thanks for clarifying.  That confirms some of what I was observing by trial and error, and answers a few more questions.

One more question ... for the mini-A to mini-B adapter (required by the OTG port), which end plugs into the Tobi OTG port?  The two plugs (mini-A vs. mini-B) do not appear to be plug-in compatible and my Mini-B plugin fits the Tobi side.  

Or is the Belkin hub you mentioned designed to plug into a mini-A style connector?

Just hoping to maximize the chances that I order the right stuff the first time. :-)



On Thu, Jul 21, 2011 at 2:16 PM, William Pretty Security Inc <bill.pretty@xplornet.com> wrote:


First of all, here is the link to the wiki I was talking about: http://gumstix.org/getting-started.html


As for the USB hubs, it may not be obvious from the documentation, but they do come with their own 5V power supply (about 2 Amps!)


The type of cable I mentioned with the Digikey part number, is also available from Gumstix. Delivery is just faster from Digikey.

However a straight mini-B to mini-B cable WILL NOT WORK. I ordered several before I figured out what was wrong L

You need a “Mini-A to Mini-B” cable. They look the same, which sucks, but one of the pins on the connector is grounded.


This web site has a good explanation of the various cable types: http://www.accesscomms.com.au/Reference/USB.htm


Depending on how handy with a soldering iron you are J I spliced the power connector for the Tobi and the connector for the hub

together and connected them both to the same 5V 2 Amp power cube. Works like a charm …


good luck;




"People sleep peaceably in their beds at night only because rough men

stand ready to do violence on their behalf." - George Orwell


From: Curtis Olson [mailto:curtolson@gmail.com]
Sent: Thursday, July 21, 2011 1:10 PM

To: General mailing list for gumstix users.
Subject: Re: [Gumstix-users] Capabilities of USB OTG port


On Thu, Jul 21, 2011 at 11:28 AM, Curtis Olson <curtolson@gmail.com> wrote:


USB Hubs that work for me:        Belkin    F5U700-blk         – 7 port hub

                                                                Belkin    F5U403-blk         - 4 port hub


The 7 port hub had trouble powering high power devices (Alpha WiFi adapter).


Hi Bill, I appreciate your responses, but when I look up these devices I don't see any evidence that they are externally powered.  Have you been able to use the USB-*OTG* port on the Tobi without an externally powered HUB?


Hi Bill, ok, I do see that in one of the later pictures on the newegg site, there's a port for power and a power supply with the 4-port hub you listed.  So as best as I can tell,

The both USB-HOST and USB-OTG ports seem to require a hub to get them to do anything (at least with the devices I've tested.)  And in addition, the USB-OTG port doesn't provide 5v power so to use the USB-OTG port requires not just a hub, but an externally powered hub.


Does this jive with other folks understanding?






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