How to make a tablet LCD be recognizeable as a touchscreen monitor?

Hello, to the Great TH Forum!

I'll try to be quick :sarcastic: First, if this thread needs to be moved then please do so, mods. Second, I tried doing a forum search for my topic with no results... PLEASE post thread links if you feel they'll help answer my question. Third, be gentle with me; I'm decently knowledgeable in electronics but this area is hazy for me.

Sooooooo... I've got a project in mind. I want to put a fully functional computer inside a 2009 SUV. There are already plenty of options for the PC, enclosure, smart-power solutions, mounts, OEM-integrations, audio-system-tie-ins, GUI software, etc so this part of the project is simple. I'm open to suggestions with the above stuff, as well.

The plan:
-i5/i7 CPU, 8GB RAM, good-sized SSD, a GPU that can do 1080p
-Wireless N, bluetooth, [possibly mobile internet chip]
-BluRay drive, iPod/USB/headphone/peripheral ports
-**touchscreen display to eliminate keys, maximize screen size**

The problem:
-you can't get an HD touchscreen. You can buy EITHER an HD screen OR a touchscreen
-NOTE: if someone finds me an HD screen, the screen quality (gamut, backlight, contrast etc...) will probably be terrible

The solution:
-there are a truckload of beautiful, shiny, sensitive HD screens found on tablets
-there are plenty of replacement LCDs and digitizers you can purchase for tablets (Xoom, iPad, ...)

The question(s):
-What are the obstacles to making a tablet screen be recognizable as a touchscreen display for the computer?
-What parts combine to make an LCD a "display peripheral", and what is different in a tablet LCD?

Bonus question:
-Who WOULDN'T want a big, clear, HD, glass touchscreen in their car?

Right away I will state a few things. Firstly, I know it is easier to possibly mount an entire tablet as my PC, but a tablet is simply not powerful/upgradeable enough for me, thank you. Second, I KNOW that tablets are highly proprietary because they're so small and advanced, but my project should still be doable for the simple fact that these devices still use standard protocols. So even if there are proprietary parts, there should still be a way to connect the tablet screen to a proper controller, inverter, blah blah blah even if I have to fabricate something on bread board.

I think i've said enough to release this thread to the community. If someone has the urge to comment "it can't be done", don't bother posting. If someone says "it's too hard", then you're probably a quitter and shouldn't post either. I understand this might be tough. Sometimes projects fail. But other times they work and then I look awesome :)

Other hurdles to consider... iPad 3 screen is nice but most Apple stuff is SUPER proprietary, also their LCD has a massive display with a video controller built by... aliens? Also the compact nature of tablets might mean that components are soldered/inbuilt on the mobo, so i may or may not be able to salvage parts. Another important note is driver issues and display recognition.

I want POSSIBLE, people! I'll answer as many questions as needed. Thanks so much for the wealth of info and generosity on THF, and I look forward to your help. PLEASE feel free to post threads or links that will educate me/others on the complexity of displays!!!

David H
16 answers Last reply
More about make tablet recognizeable touchscreen monitor
  1. I found a parts breakdown of the Motorola Xoom. How difficult would it be to isolate or salvage some of these components from the mobo?$359-92-IHS-iSuppli-Teardown-Reveals.aspx

    Bump! I'm pretty good with this stuff but I just need some pointing in the right direction.

    David H
  2. Found a datasheet for the Xoom tablet LCD screen...

    With these parameters, would it be possible to fabricate or search for existing video controllers for this screen?

    I can also find a Xoom mobo on eBay in working condition. Obviously a touch screen is another dimension to the Xoom LCD, but right now it seems i can acquire stuff relating to the actual screen. Perhaps the eBay mobo could be used in controlling the touch screen digitizer?

    Help, please!

    David H
  3. I think you need to begin with what size screen you want and if you prefer capacitive or resistive touchscreen.

    With the system specs yo posted why the big need for 1080?
    Personally I'd do 720 just so I would have icons that were bigger than pencil point and test I might actually be able to read. 1080 is nice for seeing detail in movies but not so good for pc stuff on tiny screens or large screens from a distance IMO.
  4. I think i've decided pretty conclusively that I'm going to choose a 10.1" Motorola Xoom touchscreen LCD. As my above posts indicate, i've got a small hill of data for the Xoom screen and it's a beautiful 1280 x 800 resolution. It's not exactly a 1080p SCREEN situation... the COMPUTER being 1080p capable isn't actually related to my screen requirments.

    Anyways, i've got the LCD screen model figured out and i've got the touchscreen digitizer model figured out. Done. I just need to know the SPECIFICS of extra equipment... video controller, power inverter, drivers, all the OTHER stuff.

    David H
  5. Holy moly, people! Is there no one that's able to help here?

    After some research, I've realized that the Xoom touch screen has its touch controller attached to it... separate from the motherboard. Furthermore, the Xoom LCD seems to contain the backlight and the video controller.

    If this is true, then I should actually have most of the hardware. The hardest thing (as for hardware issues) now would be to set up a power supply that can handle 12V input (from a vehicle).

    However, an important question needs answering: even if all the hardware works properly, what types of software/drivers/firmware is necessary to turn this LCD touchscreen into a plug-and-play monitor?

    David H
  6. your not goiing to turn it into a plug and play monitor. You need to manually set the resolution and refresh rate within whatever driver you find to work with it, just like the good old days.

    I think you're major hurdle is going to be how to interface the GPU's output with the input to the screen.
  7. As far as I'm concerned, i've got most of the hardware I need to run this thing. The ONLY thing i would need is someone to do some C++ programming to create some drivers for me. If the drivers were added into the registry then, to me, that's plug and play.
  8. I know its old. In case you haven't moved past this problem...... You'll need an Android app that converts the Xoom into a touchscreen monitor. If such an app is not readily available, you need 3 pieces of software:

    1) An android app to display data that emerges from the PC

    2) An android app to send touch data to the PC

    3) A PC application to make windows believe there's a touchscreen monitor. This would then take video data from the PC and send it to the Xoom, while also transmitting touch data in the other direction.

    I believe its definitely possible to do, and I do hope you are successful, such versatile applications are somewhat lacking.

    EDIT: Sorry if it sounds generic and obvious. The reason I broke it down, is that its very easy to find open source apps that do one of the above.

    1) -> Some VNC application readymade

    2) Not sure, if you can find one.

    3) This is a bit hard, need to write a driver for this, that interfaces with the other two apps.
  9. Hi there;

    It's not that I'm using a functional Xoom and just plugging it into a PC for the display. I'm using the touch/LED display assembly from the Xoom only. I was initially considering using the display controller from the Xoom, but I now realize that it is EXTREMELY proprietary not only in hardware connections but in driver architecture (its android based). Even though I was considering grabbing the display driver from a Windows 7/8 tablet, but again the display controller is way too proprietary to work with.

    Solution: getting a different display controller. So far seems to be my best bet. Those guys are intelligent enough to write the code for any display you throw at them, but they've got some serious display controllers to offer.

    So I'll be using one of DV's controllers when I'm ready to see this project through. And actually I did buy myself a Xoom display, but after further consideration I may go all out and opt for Apple's lovely new WQXGA 13" Retina Display; really by the time I want to complete this project (summer 2013), there should be a number of small super-res displays available.

    So here's the answer to this type of less common question...

    How to take a tablet display and transform it into a plug and play PC monitor?

    1. First thing, pick your screen. A great place to start is and search by specification... unless you've already got a screen in your sights (pun intended).

    2. Go find the datasheet for your screen. Google is your friend, as may be the manufacturer. Datasheets will have specs, electrical characteristics, etc.
    ***Without a datasheet, basically abandon hope. You need that datasheet. For a SLIM chance of reviving your project, either contact a display controller company in case they've dealt with your screen before, OR find a display controller that might work then plug it in and hope for the best (don't expect any/most/all features to work if you're pulling the 50/50 move)***

    3. Ditch the tablet's proprietary display controller and contact a display controller manufacturer about options for your screen. EarthLCD has options, I've chosen to go with DigitalView. There are MANY options and websites, get Googling! What's do you need in your display controller? Well, is your screen LMDS? LED back lit? Resolution and brightness? Does your screen need PWM?

    4. The controller maker will need to program the controller to the screen characteristics. After that you'll need to contact a cable maker in order to get a custom cable between the controller and screen. Quantenna is a good custom maker. Check them out, or ask the display controller maker for suggestions.

    5. Plug and play, dude.

    6. If you're a computer/software engineer, you're awesome and you don't need any of this info cause you'll do it yourself.

    Cost? Not cheap. Some people are doing cheap and dirty mock ups for like $100. Me, I'm choosing quality since I plan on attaching this (with touchscreen overlay) to a $4000 computer. A Retina Display screen is like $500, the proper Digital View controller is $250, a cable is $100, and programming costs (if the controller doesn't immediately recognize the screen) might be like $2-500. So... not cheap, but with my touchscreen overlay i'll have one amazing car computer.

    Hopefully this can be a general resource for someone else on TH or elsewhere.

  10. Oh yeah, a note about the tablet's touchscreen. The short answer is that you should try finding your own touchscreen overlay kit that uses a USB connection to interact with your computer. They plentiful and require zero screwing around. You'll probably (as I have) be able to find the exact same touchscreen the tablet uses, just with a generic USB I/O instead of some other I/O. Even though many tablets use an off-the-shelf touchscreen, they intentionally use some type of super stupid proprietary I/O connection... for no good reason IMO.
  11. But why not use the whole functional tablet? You can completely sidestep the proprietary-ness. Its also far more standard. Your selection of tablets is far wider if you choose to only write drivers rather than rip a screen off a tablet.
  12. I don't intend to be argumentative, but I would technically see your method as allowing LESS screens to work with. If I use the method I discussed, my computer will see whatever the display controller's drivers tell it to see. And since it can be programmed to accept anything in the screen world, my options arent limited to tablets, but laptops as well.

    The other important reason is that I can reduce the amount of MY time and effort spent researching and finding the right people to help mr achieve this task. For run of the mill tasks, the internet offers tons of novice programmers who can do general stuff. But (as my MONTHS of searching have shown) as soon as it's a unique problem or creation being contemplated, the airwaves go silent. Smart ppl are hard to find, plain and simple. I've encountered this conclusion in MANY different projects of mine, ranging from CNC machining and metallurgy questions all the way to long-range wifi and cellular networking systems.

    My current plans have both hardware and people with the means to achieve my goals. Sometimes its just nicer to throw money at a problem. And for no more than double the price of buying a 1080p tablet, I can have a brighter, larger, 2560 x 1600 screen in my hands. Hopefully you understand my points and my ultimate direction for this project.

    Btw thanks for your input.

  13. Hi dave,

    I think I may have a much easier solution for you... I've been investigating a way for my wife to have the full power of a PC in a lightweight tablet. I found a very simple solution.

    All you need to be able to do is use the tablet to control a remote desktop of a PC. That is rather simple, and you can still use the tablet as a tablet when you want to. I found this software for an android tablet that allows an android tablet to log into a PC accross a network and view the PC's screen and control it. You would need to set up a wireless network for it to connect to the PC, but that's it.

    No programming special drivers, soldering, or running special wires from the PC to the tablet screen. The only issue is if you want to be able to play a FPS game or stream 1080p video, althogh the streaming doesn't even look that bad.

    I havn't actually done this yet, I just found the software last night ad haven't bought a tablet yet. I'm going to see f I can find one with a really high speed Wi-Fi in it to see if I can get smoother video playback than what they showed on the splashtop site. It showed 20fps at 1080p with 40-50ms latency over wi-fi. You might be able to get smooother video at lower resolution. It also might be possible to use a USB network adapter and run a wire to increse framerate and latency, but I don't know on that. That idea just popped into my head as I wrote this. Hmmm... it might also be possible to use the wired and wireless netowork at the same time bound together to increase speed even more...

    Good luck in your build but um... what city do you live in? If you get this all working in your car I might be safer off the streets...

  14. Hi kirk;

    In and of itself that remote desktop app is really cool. If I ever get a tablet I'd really think that'd be a cool way to use a tablet as a mobile workstation or a multimedia device with unlimited storage around the home.

    Alas, my car computer idea wants what it wants. Super quality display with multitouch ability.

    And as far as the whole "safer off the streets" comment, I know its just poking fun, BUT riddle me this:
    How many times have you texted (even quickly) while driving, changed the song playing, or answered a call by grabbing your phone? The major motivator to having this massive touchscreen computer in my vehicle is to have those features while being SAFE. I'll explain...

    Tablets and phones can't take advantage of state of the art speech software, but a super fast computer with good mics can use that stuff amazingly fast. And if you've ever trained Dragon Naturally Speaking to your voice, it is INSANELY accurate in detecting vocab, punctuation, and action requests. So, now imagine your phone is in your pocket, but upon receiving a text or call you can reply with perfect clarity and without having to look off the road, all through the power of a good computer in your vehicle. And yes, it is obviously true that "hands free" safety is not the same as "focus only on driving and nothing else" safety, bit this is my attempt at reducing extraneous risks while still multitasking.

    Furthermore, the massive screen I want in my dash will serve an important feature, aside from being awesome for navigation and watching movies. My wife and I are on the road more than 60,000km a year, and lots of that time is spent driving at night. Soooooo I'll be installing an infrared camera wity infrared headlight to allow assistance with night driving, an idea I've had for years and that many luxury cars now have (such as the Merc E-class).

    Oh and lastly, if I ever find the money and time to do any of this, I intend on spending money for an awesome audio DAC to have excellent music... something only a good computer can make use of.

    So as you can see there is not only the desire to have a super cool system, but to NOT sacrifice safety while being awesome. Even yet, Id hope to be safer on the road than without this system. Im pretty sure you and most others would agree that its a bit idealistic to assume north Americans are gonna suddenly drop their handhelds in favour of safer, no-distractions driving. However it is totally fair to expect north Americans to grow a brain on top of their necks and exercise a bit of intelligent/responsible thought while multitasking.

    Hopefully this clears up the "why" of my complicated setup. This won't be a simple system. It will have GPS for security, wifi and cell antennas, and a bunch of other diddlies. Pow!

    Again, though, I've got more important places to spend our money. So this may never actually happen. My preference is to reduce our personal debt instead of undertake this kind of lavish (awesome) project. But dreaming is fun.

  15. Hi Dave,

    Yeah, the safer off the streets comment was in jest, but glad you are thinking about it. The voice activation thing is nice, the thing that wories me a bit about people with touchscreens on their dash is that you actually do have to look at it to select something. At least with old fashoned knobs you can sort of figure out what you are looking for by feel without looking. Sadly, you have more faith that people will grow a brain on their heads and not text and drive etc.

    I'm also a dreamer and have been thinking about your idea all day. I've been thinking how cool it would be to have it so the tablet can be inserted and removed from the dash. If you had a strong enough Wi-Fi you could use it at a pretty good distance from your car and still have access to a full power PC.

    As far as your idea goes though. My wife was looking today and found several multi-touch monitors up to 22-24" for under $400. That may be too big for what you were thinking, but a quick search on Amazon finds several from 7"- 16" are already set to use a HDMI and USB interface, several under $300.

    Probably the best option that would do everything you want it to do would be the Microsoft Surface Pro. (not the RT that is out now) It is supposed to be out by the end of the month. 10.8" 1080P ten point multi-touch screen. It's a full PC with Windows 8 and an Intel I5 processor. 128gb SSD, 4GB Ram, USB 3.0 , and bluetooth 4. USB 3 is fast enough you could easily put additional storage on it and not have speed issues. the more I think about it the more I think this would be the easiest and possibly the cheapest way for you to get what you want now at a reasonable price. It won't be as fast as a desktop, or even a top end laptop, but it is a full PC with 1080p touchscreen.

    I suppose you could also use the new Asus TaiChi It's available with a 11.6 and 13.3" screens. If you mounted it so it was easy to pop out of the dash it will double as a very nice full feature ultrabook or tablet PC. and you can get it with an i7. I've been looking at the surface and the taichi for my wife to use as a full computer tablet, but she's afrad they will be too heavy to use as a tablet and hold for hours at a time. Which is why I started looking at the remote controlling a full pc with a lightweight tablet.

    Another option that I just saw and would be really easy to set up for what you want is an all in one PC that is actually built in to a touch screen monitor. You may be able to find one with beefyer specs than the Surface Pro or TaiChi, and with a bigger screen if that's what you are looking for. You might even be able to find one that's cheaper than the Surface and Taichi. All you'd need for it to work would be an inverter for power. I'd recomend also putting a nice UPS in the car as well so you'd have some battery time. If you got one with software you could set it up to shut itself down before the battery dies.

    if you want chaper and all you need is what you listed in your last post, my wife also tells me that her Android phone will do speech to text, navigation and everything you listed that you wanted your system to do, so it will work with any android tablet or phone with version 4.0 or later with just downloading a few apps. I'm all for dreaming the big project, but when it comes to spending the money if I can get 90% of what I want for 1/4 the price to make it easily affordable now instead of in the distant future I say go for it.

    Good Luck,

  16. Why did this thread die?! So much potential!

    If someone did end up getting this hashed out for a commonly desired touchscreen size, diagonal 8"(double DIN), 10.1", and a larger size maybe 12"? And had it made to plug and play with a common OS (i.e. Mac or Windows). They may be able to make quite a few bucks of it by bulk ordering and then selling privately at markup.
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