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12 Posts

05-11-2014

Texas, USA

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  • Posts: 12
  • Registered: ‎05-11-2014
  • Location: Texas, USA
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  • Message 1 of 4

USB OTG charging mode

2014-05-11, 18:27 PM

Hello, I've done some fairly extensive research on the subject, and melted quite a bit of solder "testing the theory," but I can't seem to find the right resistance value to use to enable OTG host mode with charging enabled on lenovo devices.

 

According to the USB OTG standard, having pin 4 (id pin) of a micro USB connector tied to ground through the right resistance will enable the OTG device to enter host mode, while still acepting power to charge the battery(s) from the USB line (i.e. allows you to use a USB keyboard/mouse/drive WHILE charging your tablet).

 

I know that, although the otg "standard" implies that 36.5Kohms is the correct resistance to enable this mode, it appears that no manufacturer has enabled that correctly (Samsung used 100Kohms and Sony used 68kohms ... not sure of others), so can anyone tell me the right resistance to use for lenovos (I have an S6000 and an A1000), or if lenovo, for whatever reason, simply failed to impliment this feature of the standard altogether?

 

Any ideas/information (besides "have you checked with the standard resistances of 124K, 100K, 68K, and 36.5K" ... since yes, I have) would be greatly appreciated. :)

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12 Posts

05-11-2014

Texas, USA

18 Signins

269 Page Views

  • Posts: 12
  • Registered: ‎05-11-2014
  • Location: Texas, USA
  • Views: 269
  • Message 2 of 4

Re: USB OTG charging mode

2014-05-16, 19:26 PM

Does anyone have any ideas on this one?

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2 Posts

12-29-2014

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  • Message 3 of 4

Re: USB OTG charging mode

2014-12-30, 9:07 AM

Not really the answer you are looking for, but these guys http://www.ebay.com/itm/Exclusive-Lenovo-Thinkpad-8-Micro-USB-Host-OTG-Cable-and-Charging-for-Tablet-/331286115138?pt=US_USB_Cables_Hubs_Adapters&hash=item4d2230f342) have apparently figured out the answer for the Lenovo Thinkpad 8.

 

So it seems that it is possible on some Lenovos.

 

Could be interesting to obtain one of those cables and see if it works on other Lenovos...?

 

Best of luck. Would love to know the answer if you figure it out (I'm interested in the Lenovo Yoga 2 10)...

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1 Posts

01-24-2016

Bulgaria

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  • Registered: ‎01-24-2016
  • Location: Bulgaria
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  • Message 4 of 4

Re: USB OTG charging mode

2016-01-24, 16:46 PM

So I tried this sheme [IMG]http://media.snimka.bg/s1/5134/036512535-big.jpg?r=0[/IMG] . But no result. Finaly I use variable resistance 100kOhm and the result is that when the resistance is under 4.8kOhm the flash drive is working but tablet is not charging. When the resistance is over 4.8kOhm the tablet is charging but the flash drive is not working.
Please help!!

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