Friday, October 24, 2014

Chromebook Pixel 2560x1700 LCD to DisplayPort Adapter

This is a project I've been dicking around with on and off for over a year. I bought the panel shortly after they became available (which is probably around the time Chromebook Pixel was released), and made a few prototypes in my (very limited) free time that didn't work for one reason or another.

First two prototypes I made the mistake of making them double sided, not realizing just how fucking annoying it is to solder 0.4mm pitch connectors on the back of already populated PCB. First one I used TI's TPS series of WLED drivers, which didn't work as good as I expected, so I scrapped that one. Second one I switched to ROHM driver, which worked better, but I hooked it up wrong, which didn't allow me to bring drive voltage above 5.5V making the panel pretty useless brightness-wise. Finally the third one, I redid the layout so that it was all on one side, making much easier to assemble and to reduce potential fuckups from having to bake the board twice.

The end result is pretty nice, though I'm fairly happy with my 4K Dells at this point.

As usual, high resolution photos are in the Google Picasa album:

https://plus.google.com/photos/101126269564358156827/albums/6073976289400453185?authkey=CI_pmIrn29f0Uw

Thumbnails below (maybe click to embiggen works)
Windows 8.1 monitor control panel with Chromebook LCD below dual 4K Dells

The board itself. Surely didn't cost me anywhere near $130 even if I was going to assemble only one.

Another look at the board.

rev2 prototype with ROHM driver. Failed.

rev1 prototype with TPS driver. Failed for some reason I can't remember.

Yes, 2560x1700 in ~12 inch. Very nice.
The Chromebook Pixel panels are available on eBay for as low as 70$-80$ shipped. Unlike the iPad 3/4 panel, it does not come with a fpc/microcoaxial cable for connecting to the driver board. I ordered 5 samples from nice folks I've dealt with before for cables, and it cost me $100 shipped for 5 - which is a bit high, but would probably become cheaper if I was going to get more of them.

14 comments:

  1. Awesome is the first word that comes in my mind every time I see a new post/project on your blog. I suppose that this is currently just a POC, a kind of beta rev.1 hardware board due to the position of the ribbon cable connector on this design that can cause problems (folding the cable isn't good).
    However, I was wondering if you plan to sell these cards (and the future revs) on your shop in the near future. In fact Chromebook Pixel Panels are very interesting for certain applications.

    Have a good day and keep up your good work. :)

    Regards.

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  2. Oh whow, this looks really promising, can't wait to hear more about this.
    just checked the cost of these panels.. $63 USD inc shipping on amazon.
    not to bad!!

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  3. Hello.

    You sell a plate for Chromebook? I want to build a cintiq using a display and a tablet without display. If you could help me, I would be very grateful.

    Sorry English, I used the translator.

    Thx!

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  4. If you can sell a DisplayPort Adapter for Chromebook please contact: nadaaoextremo@gmail.com

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  5. I did say I only made one, and if I ever do make more than that, I'll probably need to modify the pcb a bit, as current version is really ugly and not useful.

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  6. Well ... I quite liked the project that worked (third). I thought it is simple and functional. Unless he has not reached the maximum resolution. In this case it needs improvements.

    Anyway, if not bother, could pass the project model developed so I can try to do?

    Thank you and look forward to answer.

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  7. Timmy were did you get the cable from? I have been working on a DIY theater projector using that same display. Been fighting to find a place for that wire. Ordered one from ebay but not sure if its going to work or not. I may make up a board to go from the 20474-040E-12 to Displayport. Just not to sure if it going to be worth it. Any information would be greatly appreciated.

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    Replies
    1. Oh, sorry for late reply.
      I ordered it from usual place where I get coax cables made for work - but it's probably not very cost effective for a one-off.

      You will probably need to make a PCB to mount the 20474 IPEX connector - there's no way you're hand-soldering anything to it, it's 0.4mm pitch.

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  8. Thanks for getting back to me been having problems with coming up with the wire to make this work. Any drawings to help me would be greatly appreciated. Bought a wire off ebay that was for a 15.4" display.The LVDS wire and its doesnt have all the wires and no chance at fixing it. I am in need of the wire and board just for a adapter no back lighting. Pleas e-mail me back at laytont@reprogle.com. Thanks a million.

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  9. If you start selling, I'll probably buy 3...

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  10. If you start selling, I'll probably buy 3...

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  11. If you start selling, I'll probably buy 3...

    I really hope this project

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  12. Hey, can you tell me where you bought that LVDS 40 pin cable at? I've been looking for one that works with the Chromebook Pixel for days.

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    Replies
    1. I had it custom made to specification (basically 1:1 connector and change pitch to match board). it's not the same cable as used by chromebook pixel, I actually have no idea what kinda cable they have in there.

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