Selfmade Charge / USB adaptor for TF810C

Discussion in 'Asus' started by nightworking, Feb 21, 2013.

  1. nightworking

    nightworking Pen Pal - Newbie

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    Hello everyone,

    I bought the tab without the dock, but I knew something like this should be possible to make. See for yourself, thought I should share this:

    USB.jpg

    You need:

    - A cheap USB 3.0 cable (you will need the additional pins in order to be able to switch the power supply to 15 V)
    - An original ASUS USB dongle (I bought a spare one since I didn't want to harm the original one)
    - Some soldering skills

    Instructions:

    - Look at the original charge cable. There is an additional center pin in the front of the USB plug. Actually this is no standard USB 2.0 plug. USB 3.0 plugs have these pins. The original charge cable connects this pin to the power supply's output. This switches this output from 5 V (which you would get with any regular USB cable) to 15 V. At 5 V, the tab would not charge, it would just run off the 5 V. At 15 V, it does charge the battery.

    - Therefore I took the USB 3.0 cable and made the connections as follows:
    - black wire and shield (USB ground) --> solder both together to ground/shield of the USB dongle
    - red wire and USB 3.0 center pin (usually the copper wires inside the extra twisted pair wires) --> solder together to the +15V Vcc pin in the plug. It is quite easy, even with a larger iron.
    - bridge the pins (8,9 denoted in the image below) in the dongle which tell it to accept 15 V (I don't know if this is even necessary, but it is explained in the pinout). Note the pin numbers do not perfectly match the real ones as I noticed, but you can easily recognize which ones are meant.

    - I was able to put the cable a bit inside the dongle case and put expoy around it, so this is quite solid now.

    - Now I can use USB and charge my tab at the same time. Works like a charm.

    Also see pinout here (source: Asus Vivo Tab RT 36-pin connector pinout. - xda-developers)
    Asus VivoTab 36 Pin Connector Total 1.jpg

    Regards
    nightworking
     
  2. Steve S

    Steve S Pen Pro - Senior Member Super Moderator

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    night: Nice job...!
     
  3. sssaaammmcn

    sssaaammmcn Pen Pal - Newbie

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    great. nice job
     
  4. Breed

    Breed Scribbler - Standard Member

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    Good job, man! Is there a risk of whatever's being connected via USB of getting 15V rather than 5?
     
  5. nightworking

    nightworking Pen Pal - Newbie

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    I suppose not -- as long as you connect the 15 V to the Vcc in terminal denoted in the drawing above.
    However, if you are not absolutely sure what you are doing, I'd recommend to let it be. I like to hack things, so I took the risk.
    I have a 4-port USB hub connected with my Keyboard, Mouse and Printer. It works. :)
    You might have to connect the USB after waking the device up from connected standby, but probably this is a driver issue, maybe the same as with the dock's peripherals. I guess it has nothing to do with my hack. Actually, I guess the dock does exactly the same, it just looks differently. Actually, one could build their own $40 dock this way, if you put it all into a nice enclosure.
     
  6. Breed

    Breed Scribbler - Standard Member

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    I have the dock with mine so I don't need to attempt this, thankfully. It was more curiosity. I wish I knew enough to modify electronics like this. Unfortunately programming bare bones metal is as low as I've ever gotten. Good to have the knowledge to be able to create/modify the metal too, though!
     
  7. jgrobert1968

    jgrobert1968 Pen Pal - Newbie

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    That's great! I am so glad that others have gotten some use out of that schematic. I have searched and searched, and finally, got a break on the manufacture of the 36 pin connection. I happened to glance at the connector on the USB charger cable, and saw some writing. “LOTES 1233”. So, I Googled it and sure enough Lotes Co. LTD. Showed up. See LOTES connectors,CPU Socket,Coolers and Antenna for Notebook Computer, Personal Computer ,Mobile electronic device,Ditial Video I have sent an email to both the Main office in main land China and to their South Korea representative, Semsus Electronic Co., Ltd. I received a reply from the South Korea representative, which forwarded the message to the main office. Since China is on Holiday, I don’t expect a prompt reply. Sadly, the South Korea representative did inform me that the company does not have a United States distributor.
    Posted below are a few more pix. The stats of the connector are that it is 15mm x 2 mm, the 34 data pins are set on a 0.5mm pitch (0.5 mm center to center) and are 0.2 mm wide. The Two power pins are 0.5 mm wide, set at 1.0 mm from the interface card edge (PCB that the pins are soldered to, to provide a platform of connection. The interface PCB is 12.0 mm wide where it slides into the actual connector.
    Note of the connections: Both sets of USB data carrying pairs (pins 27-28 and pins 29-30) are capable of connection of a USB device.
    Would love to have other’s input on any experiments with the pinout of this connector. I have a feeling that a USB 3.0 capability and Audio OUT signal also will be found to be capable via this 36 pin connection. I’m currently working on constructing my own homemade docking station for my Vivo Tab. A rep at Asus says he doesn’t know of any plans for such a device from Asus for the Vivo Tab.

    Cheers. jgrobert1968 DSCN2689.jpg 36 Pin Connector 1.jpg
     
  8. nightworking

    nightworking Pen Pal - Newbie

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    Good job! It would be great to have the full pinout sometime. It might be possible to build a simple micro-dock with 2-port USB, audio-out and HDMI out for just a few bucks using cheap cables. The idea with the 2nd USB port came to my mind as well.

    BTW: I notice the tab still supplies some power to the USB device in connected standby. My 4-port USB hub which I connected to the adaptor has a red LED inside (just an optical effect) and I can see it is still lit in connected standby. This is quite annoying since it means increased consumption, so right now I always disconnect the USB hub before entering connected standby. Any ideas how to change this?
     
  9. jgrobert1968

    jgrobert1968 Pen Pal - Newbie

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    Yeah, I'll work on that, also. The issue is that the USB adapter dongle has a linear voltage regulator (labeled U1 on the PCB) in it that is activated when the dongle is plugged into the tablet. I'm figuring that the ground leg of the linear regulator "becomes" attached to ground when the dongle is attached to the tablet. That being said, it might be something that cannot be avoided. However, it is a possibility.......... because the power pin (for the 5V leaving the tablet) will not power up unless the dongle is detected. That must also be via a ground drain (not sure which pin, but I do see that pin 19 is not grounded on the USB charging cable (not in the pic I posted) and it is grounded on the USB adapter dongle. Need to change that in the schematic.
     
  10. wubbzy

    wubbzy Pen Pal - Newbie

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    Nice job, and thanks for posting your results. It sure would be cool to make a custom mini-dock to be able to connect the tablet to my desktop setup with just one plug. This got me thinking about how we can figure out if HDMI and audio are included on the 36-pin connector. The FCC filing has some nice internal photos here. There was apparently a schematic included, but it's treated as confidential and not accessible to the public.

    I'm wondering if an easy way to do this would be to check for continuity between the HDMI and audio jacks to the various pins on the 36-pin connector, assuming that they're connected at the same place without any sort of filtering or switching circuitry. Clearly, the dock does not have either connector on it, but perhaps the connector is wired for it anyway.

    I don't have a VivoTab yet, so I won't be able to try this for a little while, but perhaps someone else might.
     
    Last edited by a moderator: May 18, 2015
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