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Android USB OTG

Discussion in 'General Electronics Discussion' started by Pavle, Dec 5, 2015.

  1. Pavle

    Pavle

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    Sep 21, 2015
    My Samsung Galaxy S3 Neo does not provide enough power to otg devices.How to fix this ???
     
  2. cjdelphi

    cjdelphi

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    104
    Oct 26, 2011
    Two options...

    1... find a USB splitter then feed 5v in from an externally fed 5v source..

    Or

    2. Cut the cable and feed 5v in
     
  3. cjdelphi

    cjdelphi

    1,098
    104
    Oct 26, 2011
    You might want to cut the 5v coming out your phone completely, leave ground/black cable alone relying on the external power source, or leave it in to charge your phone! Maybe a diode.....
     
  4. blaablaaguy

    blaablaaguy

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    Dec 6, 2015
    Try using a powered hub.
     
  5. Pavle

    Pavle

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    Sep 21, 2015
    Can I make android to provide enough power to otg devices without external power supply???
     
  6. davenn

    davenn Moderator

    13,319
    1,767
    Sep 5, 2009
    that would depend on the device and its power requirements
     
  7. blaablaaguy

    blaablaaguy

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    Dec 6, 2015
    You should be able to power flashdrives, keyboards, and mice, but external hardrives wont work without external power.
     
  8. cjdelphi

    cjdelphi

    1,098
    104
    Oct 26, 2011
    A 5v usb battery bank will do for a small load..
     
  9. Pavle

    Pavle

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    Sep 21, 2015
    I want to make android to provide enough power to otg devices without external power supply???
     
  10. garublador

    garublador

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    Oct 14, 2014
    My Googling has shown that there is no known way to make the S3 Neo output 5V for OTG. It may be a hardware limitation. It looks like you'll have to get a Y cable if you want to use OTG on the S3 Neo.
     
  11. Pavle

    Pavle

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    Sep 21, 2015
    How to measure voltage at micro usb port on android with multimeter???
     
  12. blaablaaguy

    blaablaaguy

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    Dec 6, 2015
    I suppose you could snip a cable off and stick the multimeters black wire to the black wire on the cable and do the same with the red wire and ignore the green and white ones coz their for data then switch the multimeter to 20v dc and read the numbers on the display, but since im a noob maybe you should check with someone who knows a bit more than me or you might mess something up. So dont do it. Dont.
     
  13. Pavle

    Pavle

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    Sep 21, 2015
    I tried but is not showing anything on display.
     
  14. garublador

    garublador

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    43
    Oct 14, 2014
    Was it an OTG cable or just a regular USB cable? Either way the ID pin needs to be shorted to common (the black wire) for an OTG port to produce 5V.
     
  15. Pavle

    Pavle

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    Sep 21, 2015
    It was regular USB cable.
     
  16. blaablaaguy

    blaablaaguy

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    Dec 6, 2015
    Did you strip the ends off the rubber the wires? You have to be touching the metal. And I thought i told you not to do it! o_O
     
  17. garublador

    garublador

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    43
    Oct 14, 2014
    I'll start with a disclaimer: Trying to measure 5V out of your phone this way could damage your phone if the wrong wires touch. It is very important to not let the red wire come in contact with any of the other wires or you could damage your phone. Don't do this if you don't want to risk damaging your phone! There's little chance you will learn anything useful and will just have to get power some other way anyway.

    In case you're curious as to what's going on.

    The way USB OTG works there is an extra ID pin that is either floating (no connection) or tied to common. If it's floating then whatever is plugged into the micro USB side is the "device" and it expects the other side to provide 5V on the red wire. If it's tied to common then whatever is plugged into the micro USB side is the "host" and should provide 5V to power the "device" (e.g. a thumb drive).

    You probably found that your USB cable only has 4 wires. Chances are they just left out the ID pin since it isn't needed. If you're trying to measure the 5V out of the phone when the phone is acting as the host you'll need to find a way to pull that ID pin to common. If you already have a OTG cable and a regular USB cable you've cut up then you might be in luck. All you'd need to do (but don't do it) is plug in the OTG cable then plug the A side of the USB cable (the part that normally goes to a USB port on a PC) and then measure from the red to black wires. Again, It is very important to not let the red wire come in contact with any of the other wires or you could damage your phone. But you shouldn't have to worry about that because you won't do it because it's been established that you'll just need a different way to power the device anyway and you don't want to damage your phone.
     
  18. Pavle

    Pavle

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    0
    Sep 21, 2015
    I cut android usb cable and connected red wire with red wire,black wire with black wire and plugged in usb port to pc and micro usb port to android and multimeter says 4.76 volts.
     
  19. blaablaaguy

    blaablaaguy

    55
    5
    Dec 6, 2015
    I think that might be the power coming from the computer. Woukd you mind telling me exactly what you trying to connect to your phone?
     
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