Mark, I would think the powered USB hub could work as it would provide power to devices downstream of the hub. They are not to be confused with a passive USB hub, which only passes on the power available from the tablet's USB port.
Powered hubs are easy to identify as they are usually provided with a wall-wart power supply. I use one to relieve the power duties to devices connected to Raspberry Pi boards. A few catches here: One is the wall-wart is usually a switching supply which may cause harmful hash on it's own. You could replace it with an older linear regulator wall-wart in that case. The other is you might have to split out the power lines from the data lines and craft up a "Y" cable to allow you to provide 5V power to the tablet, and also bring out the two data lines to a cable going to the active USB hub. I'm not sure this will even work as (you are correct in that) sometimes the data lines are shorted together in "USB Power Charger" devices, and that is used by the connected device, to detect that the port is to be configured to accept a charging current as opposed to "data mode" If you can find a way to test that the tablet will charge with a wall-wort that only has two pins connected, you should be in good shape to make the Y cable. In the case of the Raspberry Pi, I have had luck with some powered hubs being able to back feed 5V on the USB data connection and actually power the Pi via it's USB dataport. This also may work for your tablet if luck is with you :) Looks like a bit of breadboarding is in your future Mark. Warren, KD4Z On 7/7/2015 11:57 AM, Mark N2QT via Elecraft wrote: > Actually the issue is the tablet is able to supply power to external devices, > which must be > disabled when the unit is being charged from an external source. Best I can > tell in some > devices The direction of power is either negotiated by a digital message upon > connection > of an external device or by shorting or opening the data lines when the unit > is to be > charged. It looks like Dell tablets can operate with specific adapters but > there is no > guarantee this would work on another brand (and lots of review comments > saying it doesn't). > > This was all a surprise to me, I just figured I could hook things up and go. > > Mark. N2QT > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
