Research: The Scrablet – Building my own Tablet PC

Posted on November 25, 2010



Making jokes about naming, we (me and my girlfriend) came up with with some ugly names, including “Scronitor” (combining “screen” and “monitor”) which lead to “Scrablet” (combining “screen” and “tablet”). We also invented the name “CloudSack” which is the storage space for your data and “SpareMints” as backup storage items. Only Dutch people might get the joke when you pronounce the words in a specific more French-English way. But who cares.

This research article describes the different aspects of a “Do It Yourself Tablet Computer” and guides you through the research process I did to get to the point of a workable solution. And along the way I found some sweet solutions like the fit-PC2 and a controller that provides “any” laptop LCD screen with a VGA input, making it plug and play for any computer.

Related posts

Building the scrablet – A summarized photo-tour through all the main steps that lead to the end product

Taking apart the Acer Travelmatesee the insides of the Acer Travelmate and some close-ups of the screen that will be my first Do It Yourself portable Touch Screen

Taking apart the Archos 32showing you how compact a portable computer can be

The “iPad killer” – a set of conceptual sketches from 2009 for a tablet computer that can be used both stand alone as for a “see what you are doing while you are doing it” pen tablet


[November 26] Payments came in today. So I just ordered the fit-PC2 (via a Dutch vendor), the USB Touch Panel and the LCD VGA controller (via eBay and delivered from China) as described in this post. Next week I will receive the fit-PC and about two weeks from now the Touch Screen panel and LCD VGA controller will arrive.

Anticipating the China order might be a dud (either arriving dead on arrival or not at all). Hoping it will work.

[December 4] Installed Ubuntu 10.10 on the fit PC2, but could not make the drivers working for the “Intel” Intel GMA500 video chipset. Being not the only one to have this issue I googled for solutions and found a possible workaround on the Ubuntu wiki – that lead to nowhere for the fit PC2 – breaking the installation and rendering it impossible to start the GUI.

I reverted back to Ubuntu 8.04 as recommended: which has a working compile for the Poulsbo drivers, following these instructions on the fit PC2 wiki. To get through the steps I had to do be creative and do some manual work – to copy the “xorg.conf” file to the right postion – and some GUI based work to add the repositories as the default Ubuntu install does not make you Super User (Root User) by defualt.

But: it now runs on Ubuntu 8.04, using a 15 GB USB stick with a write-speed of 4 MB / second as the “hard drive” and a neat resolution of 1980 x 1020 pixels using the DVI to VGA converter between the fit PC and the screen.

[Update: February 23, 2011]

All the parts – including the replacement Touch Screen – were in February 12 and assambly and hardware modding started from that day on. Everything works and fits and right now the paint (deep red) is drying. The last parts to do are the kick-stand and the bottom-plate for the front, which will hold the glass plate of the Touch Screen. A new blog post and a commit to Make and some other similar online DIY modding sites will follow.

The OS installed on the Fit-PC is Mint 9 and Windows XP. Touch software on Mint still needs some adjusting as it conflicts with some other drivers.


Why would I build my own tablet PC?

Three reasons:

  1. To understand the workings of the different parts of a tablet PC first hand.
  2. To get back into hardware hacking – as it has been over 10 years since I seriously took something apart
  3. To research the possibilities for low cost computers – to do Roomware stuff with

Why not?

For any sane person there is likely no reason at all. And here is why:

  1. It will be clunky – You will never have access to the same resources as hardware-builders like Apple, Acer, Asus and Archos have. All their hardware is built on order.
  2. It will cost at least the same as a commercial tablet – A touch-screen alone costs between 100 to 200 euro. The motherboard between 100 to 250 euro, depending on size. In total I will spend about 600 euro.
  3. It will be ugly – As you will have to solve a lot of problems stuffing away all the parts into a compact-as-possibile housing

In short: very much like ballroom dancing. A lot of possible fun if you like to do it, but completely stupid and useless when you look at it from the outside in.

The specifications

  1. 15″ Touch screen – To allow for maximum editability (drawing and working) and high resolution images
  2. Intel Atom processor – To run Windows or Linux on
  3. USB Flash memory – to run OS (Ubuntu) from and store data on
  4. Also usable as a tablet for a PC – to edit and work on a normal power PC

Overview of the parts

  1. An LCD screen – I choose to go for a laptop screen
  2. A Touch-screen film – I choose Resistive screens to start with, mainly for price and practical reasons
  3. A compact fanless motherboard – Running an Intel Atom processor and marked as  “micro-” and “nano IPX”
  4. On-board storage – First USB, later a harddrive via SATA
  5. Battery – Either a re-used laptop battery, an external power source or some home made stuff

Where to get those parts?

Shops that offer all hardware you need are hard to find. So my first choice will be e-bay.

1: The LCD screen

The LCD Screen will be a standard LCD screen used on a standard laptop of a known brand. I have looked at monitors, to buy and take apart, but as the smallest sized 1s 17 inch and my biggest wanted screen size is 15 inch, that option will not do.

These are two out of many options:

  1. A new Sharp 15 inch UXGA LCD screeneBay – 99 USD. Resolution of 1500 x 1200 pixels, 12.0 x 9.0 inches. Nice and high resolution.
  2. A used Toshiba 5105 6100 UXGA LCD screeneBay – 25 USD. Resolution of 1500 x 1200 pixels, 12.0 x 9.0 inches.

1.a: How interchangeable are LCD screens?

In the most simple case I take a Netbook, rip the casing off and re-use the parts. But when I connect a new screen (with higher resolution) to the main board, will it work, or crash?

The main issue with LCD screens is that you can not simply plug any display into your laptop. Even when the plug and socket seem to fit. In other words: when your laptop screen breaks, you have to be carefully to order a screen of the same type or with the exact same specifications. Otherwise you might end up killing the new screen.

I am not an expert, but these two hints give some clue on the why:

From an interview with one of the people from ScreenTec in: “How to replace..“:

sometimes we require the customer to remove the LCD from the display enclosure to get the screen manufacturer’s part number from the back of the screen. The reason we may ask the customer to remove their screen is because the same laptop model may use two or more different screens which are not compatible with each other.

From this page:

If you want to bid, please tell us the Model of your LCD, then we can input the corresponding program into the controller for you. If the inverter and the LVDS cable that fit your LCD are not shown in the picture, we will replace them to make this controller board kit match your LCD.

Looking at LVDS (a abbrieviation which I encountered on other places as well) the Wikipedia article states:

Low-voltage differential signaling, or LVDS, is an electrical signaling system that can run at very high speeds over inexpensive twisted-pair copper cables.

In other words: your computer communicates to your LCD using electrical signals over a copper wire via a method called LVDS. I figure: As this is not a standard / as you can use this in any way you like, LCD screen 1 might be using a different “protocol” than LCD screen 2.

The warnings about “wracking your LCD display” indicate that the wrong display on the wrong controller programming (as the controller itself seems to be quite “standard”) might lead to the death of your (new) LCD display.

Learning about this, I decided to make things simpler and go for the safe solution.

1.b: Using the VGA output

In contrary to the “Direct connection of LCD to motherboard compatibility issues”, VGA is plug and play. So as this is a prototype Tablet computer anyway, I decided to use the VGA output of the mother board as the input for the screen.

1.c: Finding a controller to connect the LCD screen to the computer

Luckily there are products on the market allowing you to turn your LCD screen into a VGA monitor.

This is one of them, from eBay, costing 25 USD excluding the shipping cost.

It provides the following:

  1. An “unbreakable” interface – between your computer (motherboard) and screen
  2. Al the parts to make the LCD screen a “monitor” – so that you can connect it to the VGA outlet of your computer board

This also opens another possibility: to use the screen (with Touch interface) as a tablet for your computer – as I wrote about in this article. I will get back on that in the “Touch Screen” part, as a screen with Touch foil alone is not enough.

2: The touch Screen film

Touch screen film comes in at least 3 tastes:

  1. Capacative
  2. Resistive
    1. 4 wire
    2. 5 wire

I decided to focus on resistive. I want to use a pen on the screen and for that purpose Resistive is the easiest solution.

2.a: Finding the controller

As your standard off the shelf computer does not come with integrated Touch, the same challenge arises as with the LCS screen. You need a controller and something that is easy to connect.

eBay again provides a solution: a 5 wire Touch Screen USB controller.Cost: about 17 USD.

Touch Screen panel USB controller

2.b: Finding the controller and the film

Searching further, we find a 15 inch Touch Screen panel including the USB controller by the same manufacturer of the LCD screen controller. This controller apparently comes with drivers for MS Windows and Linux so it should work on both Windows and Linux machines.

Touch Screen Panel and USB controller

As it is USB driven, we can:

  1. Easily connect it to our mother board
  2. Connect the Touch Screen to another computer,

The panel (in this case) is a glass / film solution, measuring 1.8 mm. This means that when handled roughly, it will break. Glass and film are a common combination in Touch screens, so for the first version, this will do.

2.c: Alternatives for touch

Logipen device

Looking for touch-solutions I also found a reference to a non-touch solution using a pen and a receiver much like the Logipen.

I own and tested the Dane-Elec pen which uses the same technology. Basically the pen is a transmitter of ultra sound and the block has a stereo-receiver. Using both sound and infrared, the block is able to determine the pen’s position in the X/Y space of the object it is attached to.

What the Dane-Elec does not have and the Logipen does, is the option to use it as a real-time input deveice for the computer. Including a tablet-function.

I do not know yet if the Logipen does absolute coordinates. If so, it would be an alternative for touch.

Disadvantages of the pen (at least with Dane-Elec) is that when you tilt the pen, the source of the ultrasound (in the tip of the pen, about 2mm above the writing surface) will move as well, leading to strange effects like “disconnecting” lines in your drawing. It is not ideal and thus I rather avoid it for now.

3: A compact fan-less motherboard

What we need in our motherboard and computer are the following:

  1. At least 2 USB ports – to connect:
    1. A keyboard
    2. External storage
    3. The touch screen
  2. A VGA output port – to connect to our screen
  3. An Intel X86 processor – to allow us to run Windows OR Linux on it
  4. A battery for on the go – allowing us to be off the grid for a few hours

Googling I sumbled on this list: reviewing different options for small scale computers capable of running Linux. As I want to be able to run Windows as well, and with that list as a starting point I started looking for X86 machines.

3.a Small Intel Atom based computers: SBC and mini/nano/pico-ITX

Compulab fit-PC2i Computer, 10 x 9 x 2,8 cm

This Compulab machine is – apparently – sold to cosumers – see this link from Compulab for more resellers.

The fit-PC2 contains this Single Board Computer:

Single Board Computer - FITPC2i internals


The SBC-FITPC2i is a tiny single board computer based on Intel’s Atom Z530 processor and US15W chipset. It runs all standard operating systems and software packages, including Linux, Windows XP and Windows 7. The SBC-FITPC2i unique advantages include exceptionally small size, quiet, fanless operation and very low power consumption.

  • Full-featured PC single board computer, tiny and power savin
  • Up to 2GB DDR2
  • 4GB flash disk
  • DVI & LVDS display interfaces, up to 1920×1080
  • SATA HDD interface
  • PXE (Ethernet) and USB boot capability
  • HD Audio, line-out 2.0 / mic in / line-in
  • Two 1000 BaseT Ethernet port
  • 802.11b/g/n WiFi
  • Six USB 2.0 ports
  • miniSD Socket
  • Single 12V supply, 5W, fanless operation
  • Dimensions – 104 x 96 x 23 mm
  • Runs Windows XP, Windows 7 and Linux

Using Linux, a trimmed down version of Windows 7 with the miniSD port and a miniSD card up to 32 GB this can be a nice on the go machine.

And we can go even 3 centimeters smaller, searching on pico-ITX, like this Kontron pITX-SP:

Kontron Pico ITX, 10 x 7.2 x ±2.5 cm

It boasts the following features:

  • CPU:  Intel® Atom™ Z510 / Z530 1.1 / 1.6 GHZ
  • Dimensions: (H x W x D)        100 x 72mm (Pico-ITX™)
  • Ethernet: Intel® 82574L Gigabit Ethernet
  • Graphics: DirectX 9.0e, OpenGL 2.0, Shader based 2D and 3D dual independent graphics
  • Graphics Controller: Integrated decoders in Intel® System Controller Hub US15W for MPG2 and H.264 / MPEG-4 AVC
  • Hard Disk:  Single or Dual SATA II (chipset option) 1 x PATA 44 Master / Slave
  • Main Memory : 1 x DDR2 SO-DIMM up to 2GB
  • Power Consumption: 5W typical
  • Power Supply:   5V DC
  • Resolution: DVI up to 1920 x 1080 @ 60Hz LVDS up to 1280 x 1024 @ 85Hz
  • Special Features:   1 x microSD socket
  • USB: 6 x USB 2.0 (2 x at front panel, 4 x on board);

To build your own machine, you possibly need more than just the board (about 200 Euro for the cheapest board). This kit is an all in one offer costing about 400 English pound.

And even smaller with the Kontorn nanoETXexpress-SP:

The Kontron nanoETXexpress-SP, 84 x 55 mm

  • Based on Intel Atom CPU Z500 series 1.6GHz
  • Just 55mm x 84mm
  • Based on COM Express™ Pin-out Type 1
  • SerialATA, for highspeed drives
  • 1GB soldered DDR2 memory onboard
  • 4GB onboard flash drive
  • Onboard Gigabit LAN

3.b: Being practical

Beauty shot of the fit-PC2

The fit-PC2 is one of the very few very small sized Compact Single Board Computers (10 x 10 x 2.5 cm and smaller) that is available for the consumer market. All of the boards I found are primarily aimed at the professional/industrial market and can only be ordered in quantities like 100 and more. To build a fully working PC with the components will probably drive your cost towards 400 euro and more with the additional items.

So we get back to the Compulab fit-PC2, starting from 314 euro with WLAN and without drive and about 360 euro with 160 GB harddrive and 450 euro with 64 GB SSD.

What you have with the fit-PC2 is a very compact low-end computer (it will not allow you to do more than browsing the web and do the basic Office-type of stuff).

4: On board Storage

32 GB Kingston micro SD card

As harddrives are easy to wreck, and the Scrablet can fall back on an external drive when more storage is needed, the on board storage might be – in the case of a fit-PC2 – a miniSD card of at least 16 GB and likely 32 GB. Prices for these cards range between 30 to 70 euro (32 GB mini SD card) to 90 euro (micro SD card as pictured here).

4.a: SDD – an alternative option to consider

Kinston 64 GB SSD, 124 USD (November 27, 2010)

Solid State Disks are becoming cheaper and cheaper. A 60 GB SSD can be found on Amazon for 124 USD so I might consider that as an alternative for the Scrablet.

5: Running the Scrablet from a battery

Compact Energizer XP8000 Battery pack - up to "500" recharges

When you are on the road, you run your machine from a battery. I decided to stay away from modding existing batteries, although using the compact packs as delivered in the DELL 6XX series.

The goal is to be up for at least an hour, allowing you to bridge the gap between two places and keeping the battery small and light-weight and – with a little luck – also allowing me to fit the battery in the place where the hard drive would be.

There are several external battery packs available in the market and Energizer seems to dominate that market (on e-Bay and Amazon that is). Reading the reviews, Energizer might not be the first choice to make. Their battery packs can be really compact, but according to the reviews on Amazon you might not make the 500 recharges, warrenty might be limited and shipping can introduce a lot of extra cost. It is also unclear if you can use their packs in the same way as the laptop battery: “constantly charging” while you are hooked to the power grid. The price of the Energizer battery is about 70 euro.

Going through the options, the MyPall / Tekkeon myPowerAll battery and UPS seems to be a very good fit. Although almost 2 times larger than the fit-PC2 (a whopping 17 x 8 x 2.26 centimeters) it can “stay on” for ages. The price is about 100 euro.

The Tekkeon myPowerALL battery and UPS

In the end I will very likely go for what I can find in an airport Electronics shop: as compact as I can find.

5.a: Do it yourself battery pack

I have been considering this. The result is something like the image below. Depending on the voltage and output you connect more batteries in serie and in parallel.

It is sweet as a hack, but not really adding something to what I want to achieve. Not everything has to be home made.


There are several options available in the market to build your own tablet. Using used materials (and eBay to find them) might keep cost below 300 euro. In the end you will spend about 400 to 600 on materials gathered from different sources, coming close to toe price you would pay for a tablet PC built by Toshiba or Acer.

Hacking your own tablet together has another

Re-use / going low budget

I have not gone into re-using old components. Using open markets like eBay you can find broken items that might suit your personal needs. In the case of this project, the motherboard and powersupply / battery of the Asus netbook will suffice. We do not need the screen or the harddrive.

Used screens can be found as well (and maybe you do have an old laptop floating around in your hose, like I have). With a bit of creativity and scrounging around you can collect all basic parts for prices around 25 euro (screen, basic components for computer part) and add some extra 30 euros to it for the converter (and cables) you need to make the LCD screen adapted to your motherboard.

What remains expensive is the touch screen. As you can use a device like the Logipen, you could be done for a mere 200 to 250 euro (shipping costs of parts not included):

  1. 15 inch LCD screen – around 25 euro – to display your shit
  2. VGA LCD controller – around 25 euro – to make your screen adaptable to whatever motherboard
  3. Netbook with broken screen and without hard drive – around 25 euro – to run your OS
  4. A low cost harddrive or memory stick – around 25 euro – to run your OS and store stuff
  5. A Logipen-like input device – around 100 euro – to provide a “touch” interface that allows you to work without a keyboard

You might want to add a keyboard. In the compact range I found this one for 8 dollar which is flexible and can be rolled up.

The end result is a 15 inch Tablet computer that you can take outdoors and do nice tabletty stuff with.

A 500 euro tablet PC is not such a bad deal

Looking at the different parts and what is involved in a Do It Yourself solution, 500 euro for a tablet PC is not such a bad deal. Anything cheaper is simply brilliant. (Or has a small screen and therefore lower cost)

Where I will go

For the fun of Hacking, I might go for re-use of stuff that I have around, including 2 15 inch screens (from an Acer and a Dell laptop) and some Netbook with a broken screen I will buy from someone. Just to see if this is possible.

Taking it to a higher level:

Expecting some client payments to come in, the fit-PC2 is not such a bad deal for me. My work involves running stuff on multiple machines (using VMWare at this point in time) and moving towards more hardware hacking with Roomware and Android a second machine as compact as the fit-PC2 can be handy for daily use.

To use a solution like the Logipen is no solution for me. I will buy the screen, the converter and the Touch-panel to hack my own portable LCD Touch Screen / Monitor thing.

Using separate modules (a separate  screen, separate power supply and separate processing unit) also is an interesting dive into modular working (where one object can fulfill multiple roles).

I will give you an update as soon as I have something.

Posted in: 5: Research