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jdh2000

USB Y cable - simultaneous charging & peripheral use?

8 posts in this topic

I know where to purchase this. You can find just about any configuration you can dream up online. My question is: Would the tablet charge AND allow use of peripheral USB devices at the same time. I could experiment, but I do not want to break something on this brand new toy.

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Good question...

Enviado de meu V975m Core4 usando Tapatalk

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I know where to purchase this. You can find just about any configuration you can dream up online. My question is: Would the tablet charge AND allow use of peripheral USB devices at the same time. I could experiment, but I do not want to break something on this brand new toy.

 

With USB Y cable the tablet not charge, I have tryed it

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With USB Y cable the tablet not charge, I have tryed it

 

You are correct, sir. I'm not finished, so follow along with me as I experiment!

 

I began experimenting with an unpowered Asus USB/Ethernet hub to answer the question about battery charging (maintaining power) and using USB peripherals at the same time. I did not harm my V975M in any way.

 

Since pictures speak louder than words, take a look at my setup and I’ll explain what I did, and the outcome.

 

post-1777-0-05726400-1400891222_thumb.jp

 

The tablet is not powered on, but you can see the battery status on the screen. I have everything plugged in. Here’s the list:

 

1.       A short micro USB male to USB A female.

2.       A USB A male to USB A male cable going from the hub to the AC power adapter.

3.       USB keyboard plugged in.

4.       USB wireless mouse dongle.

5.       Network cable.

6.       The Asus unpowered USB/Ethernet hub.

 

I’m ready to turn on the tablet. I hold down the power button; nothing. I do it once more; nothing. I pull the power out of the hub, press the button and the tablet turns on. The network, the mouse and keyboard work. So, while it’s on I plug the power back in. It’s still not charging. I check the battery detail in settings; not charging.

 

post-1777-0-92076900-1400891281_thumb.jp

 

(By the way, once I autenticated to my network, the empty WiFi icon was replaced with the ubiquitous double computer icon made famous in Windows 95)

 

Here’s a picture of the little hub in all its glory:

 

post-1777-0-13688700-1400891325_thumb.jp

 

Conclusion: I will try this with a powered USB hub to see if it makes any difference. Look for the results a little later.

 

Adios!

 

jdh2000

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Quote: "Conclusion: I will try this with a powered USB hub to see if it makes any difference. Look for the results a little later."

 

Hello gang! I hoped that experimenting with a powered USB hub would make a difference. Short answer: it didn't. :(

 

The idea I had was to use this elegant and powerful tablet like a mini laptop; using ethernet for data, a USB keyboard and a wireless mouse. All of those peripherals work, but I can't charge at the same time. Only while I'm using battery power. Other tablets I have use independent wall chargers, but they're just not as fast or as versatile as the V975M.

 

The tablet was not harmed in any way while I tried plugging the AC adapter into the powered USB hub, or in any other configuration I could dream up (like tying different knots at each end of a rope).

 

Anyway, I hope you enjoyed my little escapade. I'll call this one solved.

 

Cheers!

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The operating mode of the Micro-USB connector is controlled by the mode/ID pin 5 of the connector.

Depending on the resistor beeing added between pin5 and pin4 (GND) these modes are switched.

In a standard short micro USB male to USB A female cable pin5 should be grounded as this cable is not predetermined for special functionality.

Take a look over here to get an idea of the possibilities.

If you are interested in the full spec you might find this one helpful.

Of course the possibilities depend on the detection method Onda used.

 

Found this one. Might work...

Edited by SciBee
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The operating mode of the Micro-USB connector is controlled by the mode/ID pin 5 of the connector.

Depending on the resistor beeing added between pin5 and pin4 (GND) these modes are switched.

In a standard short micro USB male to USB A female cable pin5 should be grounded as this cable is not predetermined for special functionality.

Take a look over here to get an idea of the possibilities.

If you are interested in the full spec you might find this one helpful.

Of course the possibilities depend on the detection method Onda used.

 

Found this one. Might work...

 

Thanks for the info! It's very much appreciated.

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I did some experimenting tonight.

 

Some time ago I bought a OTG USB cable that works fine on my Onda v975m tablet without having to cut the plastic (http://www.dx.com/nl/p/usb-female-to-male-charging-data-cable-for-samsung-i9100-galaxy-s2-5cm-67186#.VK2xHXufZ34). The resistance between pin 4 and 5 (GND) of the micro-USB male connector is 0 Ohm (short-circuited).

 

Then I bought a Y cable because I like the idea of charging and OTG at the same time. I bought this one: http://www.dx.com/p/cy-u2-266-bk-micro-usb-2-0-otg-host-flash-disk-cable-with-micro-power-for-samsung-galaxy-s3-s4-i9500-352112#.VK23pHufZ34. I specifically chose this one because it has a micro-USB female connector for power whereas most Y cables have a USB A male connector for power; this means I can still use the regular power cable that comes with the Onda. However, when I connected the Y cable charging was fine but OTG was not working.

Then I measured the resistance between pin 4 and 5 of the micro-USB male: 66 kOhm.

Yes, this cable was said to be compatible with certain Samsung phones, it looks like these phones need 66 kOhm whereras some Sony phones need 100 kOhm between pin 4 and 5.

 

So I cut open the micro-USB male connector and shorted pin 4 and 5 and connected everything again: OTG works but no charging...

When I plug in the cable the charging sign ('lighting') shortly showsup  but then appears.

 

So it looks like our Onda tablet does not like charging and OTG at the same time...

 

Or maybe there is a trick to use a resistor somewhere between 0 and 66 kOhm that would allow us to charge and OTG at the same time?

 

==> Does someone have an original OTG USB cable from Onda and is willing to measure the resistance between pin 4 and 5?

 

[Pinout of the micro-USB connector: see here http://forum.xda-developers.com/showthread.php?t=1828032

I used two needles as multimeter probes / test leads, together with two alligator clips and a magnifying glass to check the resistance for my OTG cable.

 

I am curious for your responses, maybe later this week I will experiment with a potentiometer / variable resistor myself to find out whether or not we can trick this tablet...

 

[bTW, I did not really search but until now I just saw Android phones that could OTG and charge at the same time on their micro-USB port, no Android tablets. Do we also know about other brand tablets that can do that?]

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