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Android usb otg power

Discussion in 'General Electronics Discussion' started by Pavle, Jun 10, 2016.

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  1. Pavle

    Pavle

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    Sep 21, 2015
    I have s3 neo i9301i.How can I get voltage from wifi,bluetooth or gps for usb port?
     
  2. Gryd3

    Gryd3

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    Jun 25, 2014
    You don't ...
    Voltage for the 'Radio' modules in your cellular phone do not get redirected to the USB port.
    The USB port should have it's own 5V supply that is optionally enabled if the phone is acting as a USB *host*
     
    davenn likes this.
  3. Pavle

    Pavle

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    Sep 21, 2015
    I don't have 5v for usb otg and I want to use voltage for wifi,bluetooth or gps for usb port!!!!
     
  4. Gryd3

    Gryd3

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    Jun 25, 2014
    Don't do it...
    The radio modules are usually underneath a little metal shield on the board. Access is difficult.
    You need to find the voltage regulator for this, and look at the part number to make sure it can even support the additional draw. You need to make sure that the radios inside the handset are being fed 5V, and not something else like 3.3V .
    It's not uncommon for some USB devices to draw 500mA... Additionally, depending on how you wire this, you may cause more damage when you connect the phone to a computer or charger... as the other device will be putting 5V on the line, and rightfully so.

    Oh.. one more note..
    Even if you manage to find a 5V source in the phone and connect it in such a way that it does not try to pump 5V Backwards into a charger... what good will it do you?
    You just said you don't have OTG. A USB port is not often designed to be able to switch from a host to client device. Your phone is a client... A memory stick is a client. Congrats, the power LED might light up, but there is an incredibly high probability that the phone will not be able to read the memory stick.

    You will be much better off buying and using a USB rechargeable battery pack, unless you can explain why you so badly need to redirect power from the phone's radio.
     
    davenn likes this.
  5. Pavle

    Pavle

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    Sep 21, 2015
    I want to have 5v inside my device to power otg devices.
     
  6. Gryd3

    Gryd3

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    Jun 25, 2014
    Sorry, but you are missing the point.

    There is no such thing as an *OTG Device*. The Phone itself must have the *OTG* feature.

    Normal phones operate as a USB *client* ... They 'respond' to USB hosts, and the port acts as an *input* for power.
    Memory sticks, USB Mice and keyboards... They are all USB *clients* as well.

    Now, some phones and tablet manufacturers realize that some users want to be able to use a USB keyboard or memory sticks with the phones/tablets so they began to include a feature they call 'OTG'.
    This feature *reverses* the normal behaviour of the USB port on a phone to that is acts like a USB *host*.
    If you phone does not have this feature, then regardless of power or not *no* USB device will work when connected to your phone. Two USB *clients* will not directly communicate. It would be like connecting two memory sticks together assuming they would copy the contents to each other...

    The phone's USB port is an *input* for power only, and the phone's USB port is a *client* or *slave* that will only respond and work properly when connected to a *host*.
    You cannot simply add power, and expect the phone to magically reverse the function of the USB port.

    The only possible benefit you could ever have from doing this modification, is that your phone would be able to charge the battery of other phones, or turn on the power LED of another USB device. Data will not flow!
    Additionally... side-affects may include:
    - Broken phone...
    - Broken Radio, or intermittent radio. (Bluetooth, GPS, Cellular)
    - Broken chargers.
    - Broken computers...


    Only sensible solution is to buy a portable USB charger/power-pack.
    *If* your phone supports USB OTG, you may be able to buy a special adaptor to introduce external power to the OTG adaptor... supplying 5V by yourself if no easy task.

    I strongly encourage you to abandon this project.
     
  7. Gryd3

    Gryd3

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    Jun 25, 2014
    *Note*
    There are mixed replies on other sites.

    Some say the S3 Neo has limited support for *OTG* devices.
    *It does not have the hardware to support OTG devices.

    Using a Y-Cable, some users have been able to use this feature... however, a number of users are unable to use this feature and cite a problem with the Kernel in the device.

    Modifying the hardware to provide 5V is *highly discouraged*
     
  8. Pavle

    Pavle

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    Sep 21, 2015
    How to modify software to get 5V to usb port???
     
  9. Gryd3

    Gryd3

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    Jun 25, 2014
    *Stop Asking.
    https://www.electronicspoint.com/threads/android-usb-otg-voltage.279070/
    https://www.electronicspoint.com/threads/power-mp8226-ic.278781/

    *Please try to learn some basics.
    https://www.electronicspoint.com/threads/ir-remote.277673/#post-1683557

    You cannot simply adjust software to make hardware do something it is physically incapable of doing.
    You cannot simply add a wire or simple component, and expect the software to work.

    You will need to redesign the board, or make major adjustments to the board, as well as make adjustments to the kernel of your phone.
    This is not simple, and is WAY too much work than it's worth.
    If you were to pay someone to simply adjust the kernel, you would likely pay more for their time than simply buying a phone that already works.
     
  10. davenn

    davenn Moderator

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    Sep 5, 2009
    Pavle

    you have been given wise advice from Gryd3, please listen to it


    thread closed


    Dave
     
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