Adding a Touchscreen to an EeePC901

Adding a touch screen to an Asus Eee PC 901.

Touch_Screen_Complete

I recently purchased an Asus Eee PC 901 ultra portable PC.For those yet unfamiliar with these devices, the Eee range of PC's from Asus are ultra mobilepersonal computers which although not the most powerful computers, are incredibly small. This semi guide cover the installation of a touch screen to the Eee PC 901 from Asus. With a couple of hard lessons learned hopefully I can impart to you some tips that will save you money and hassle.

 

There are many benefits to owning one of the AsusEee PC range. Low weight and long battery life are offset against disadvantages, the main one being the small keyboards.For random surfing on the couch this is not a major disadvantage, and this for me is main use that I will be putting mine to.

Another advantage as far as I am concerned is the possibilities for modification that a low cost device offers.It would appear that I am not alone in thinking this way; many others have been taking a screwdriver to their dinky pride and joys and adding some interesting modifications.As my other laptop is supplied to me by my employer, modifications obviously are a big no-no.I have owned mine now for a couple of weeks, so the modifications were long overdue.

The first modification that I just had to do was to add a touch screen.I could see some immediate advantages in this addition:

  • Web browsing should be improved.
  • PCB design work should be just about possible, mouse pads are limited in this activity I find.
  • The odd picture modification for www.justblair.co.uk should be a bit more possible.

So on to the modification.

Sourcing Touch Panels

The first thing to do was to source some touch panels.There are a few guides kicking about the Internet for doing touch screen modifications, most that I found related to theEee PC 701 which uses a 7' screen.Picking a source was confusing to say the least.In the end I plumped for a quick E-bay search.

The package that I found was described as an 8.9' touch screen kit for the Eee PC 901.The package was described as solder less which although I am not averse to using a soldering iron, appealed in that it sounded easier to install.As an added bonus, the touch screen controller included in the package also included a USB hub on the same circuit board.As I may wish to add further devices to the Asus Eee PC 901at a later date, a USB hub is something that I may find useful.The icing on the cake from the vendor was an aluminium stylus with included laser pointer and led light.This was not a deal breaker for me if I am being honest; I had doubts about the likely quality of the stylus as it was a freebie.

The E-bay Vendor that I purchased from goes by the name of new2006power. Although the Vendor states that the item was located in Dublin, Ireland in fact it was dispatched from Hong Kong.Each Touchscreen panel, controller board andfree stylus came to £64.99 delivered.

The package duly arrived and what can I tell you.It was a well packaged pair of touch screens (One for me and one for Mrs JB) The screens looked different from others I have seen on the web in that their patch cables were orientated differently (on the lower left rather than lower right) and the controller was a different shape to others that appeared in guides.Looking at the circuit board carefully, the chip included is the same as is included on the other boards I have seen online.Its origin can be traced to a Taiwanese company EETI who supply drivers and software for the controller from their website.Here is the specifications they publish for the chip.

touch_screen_chip
USB Hardware Specifications

  • Power Voltage4.9 to 5.1 VDC, 50 mVpp maximum ripple
  • Operating Frequency6 MHz
  • Operating Temperature-0 to 70 degrees Centigrade
  • Storage Temperature-65 at 150 degrees Centigrade
  • Current ConsumptionIdle 25 mA, work 60 mA, Suspend 15 mA
  • ProtocolUSB 1.1 Low Speed (1.5 Mbps)
  • Resolution2048 x 2048 (external ADC)
  • Report RateMax. 160 points/sec
  • Response TimeMax. 35 ms
  • Package24-Lead (300 mil) Molded SOIC
  • Package Dimension15.6 mm x 10.5 mm x 2.7 mm

{include_content_item 45}This raises some questions about the vendor's claims for the package they supply, but I won't go into that here.Most of the vendors lay the same claims for devices using the same controller.It is possible that EETI is out of date on the capabilities of the device on their site for instance.

Enough of the specs, let's look at how to fit one of the kits.At this point I should make an admission.But consider this first!

Buy cheap laptop computers for sale online, official Dell reseller.

Fitting the Touchscreen Kit

"I have not failed. I've just found 10,000 ways that won't work."
Thomas A. Edison

 

In my case I discovered 2 ways that didn't work before I achieved a result on this modification.I won't publish just how much this cost me in "additional parts" least of all because I can't remember how much I told Mrs. JB I spent and I can guarantee you she does.But in the process I broke one touch screen panel and damaged one 1024x600 wxga panel!

However if you know what you are doing this modification should not be this perilous.Hopefully by the time you have read this article I will have imparted onto you what to avoid if attempting this.

Step One: Dis-assembly of the Asus Eee PC 901.

Removing the screws from the underside of an Asus eeePC901
Unlike some laptops I have encountered in the past, tearing down the Asus Eee PC 901 is not the hardest of jobs.To begin with you start turning the E
ee PC onto its back.

Next job is to remove the battery from the Asus Eee PC 901.There are two clips which are clearly marked, these release the battery.Put this to the side, you won't need it for a while.

While the Eee PC 901is on its back, its time to get a small Philips screwdriver to work on the case.There are 11 screws to remove from the underside of the case, eight around the outside edges and another 3 which were previously hidden beneath the battery.Put these somewhere safe.For dis-assembly of electrical items, I keep ready meal containers that have been through the dishwasher as my containers of choice.The type that held once a curry and rice are my favourites, perhaps because of the practical separate compartments, or perhaps that I never have enough of them and must keep eating curry!

Once you have removed the screws, its time to turn the Asus Eee PC 901 back up the right way and open carefully the screen.I say carefully open the screen, because you should be aware that the hinge for the screen is held in place on the base of the Eee PC by two screws on each side.You have just removed half of these as you will see when you get the case open.


Keyboad_Clip2The next stage in the tear down is to access a further set of screws which are hidden below the keyboard of the Eee PC.The keyboard of the Eee PC 901 is clipped into place with three clips these must be pushed in gently to release the keyboard.They are hard to see, but can be found just above the F1, F6 and Pause/Break keys.

keyboard_clip_action
You don't need to press these all at the same time.As each is pressed in the keyboard, which is under a little tension will pop out slightly.As this would be a little too easy, on my and Mrs JB's machines Asus had added a little double sided sticky tape.The keyboard thus required gentle prising to release it from its place.Be very gentle here, the plastic is easily scratched, so don't lever against it.Also the keyboard is connected to the motherboard underneath with a flimsy ribbon cable that you don't want to tear.


Removing the Keyboard ConnectorOnce the keyboard is released, you need to un-attach the ribbon cable from the motherboard.Moving the board upwards you can see the ribbon connector in its Ziff socket.The Zero insertion force sockets have a tab system which must be prised out slightly before you attempt to remove the cable.Once the tabs have been pushed out, the cable should be easy to pull out.If its not, the tabs need to be pushed out further.

Remove the top side screws from the eeePC901
With the keyboard now completely removed, all but one of the six remaining base sections screws are now visible.The sixth is hidden by a warranty sticker.It might as well read "this way there be dragons", once you break this seal, you are on your own if the machine fails for any reason.The decision is yours to live with, but don't come crying to me if Asus refuses to honour a warranty claim.Took me all of 2 seconds to dive in and break the seal.You can't peal it back by the way; it's made of brittle plastic that splits too easily.Remove these six screws and put them safely into your container.

Before you are tempted to start hacking the top base of the Eee PC 901apart, the top of the base section is attached by two ribbon cables.

Remove the touch pad connector
One is attached to the touch pad and has to be released before you attempt to remove the case top.This is easy to spot as it has a blue plastic stiffening tab attached.This is another one of those zero insertion force connectors and has a cream plastic retaining tab that needs to be prised out before you attempt to pull out the ribbon...Again once the ribbon is released it will pull out without any resistance, so if it is not easy to pull, work on those tabs again.

Connector_FbuttonsThe second ribbon attached is for the additional switches on the silver bar at the foot of the screen.This cable is a bit more durable than the ribbons that you have encountered so far, and has a little more surplus.If you can pry it out from its port before removing the base top then fair enough, but don't worry if you cant, it can be more easily removed once the top is loose.The connector is a straight forward male fits female type.No securing tabs to concern you're self with here.

Next thing to do is to gently get a thumb nail into the split between the two halves of the base and pry off the top.This may take a little experimenting to get the two sections to separate.If you don't get success at one point of the case, keep moving your thumb nail around the split until you feel some give.Don't be tempted to use a metal edge such as a knife or screwdriver here.The plastic is fragile and could easily be damaged.A thumb nail should be enough to separate the halves.If you left the button connector attached to the motherboard, now is the time to remove it.Now both halves should separate and you can remove the top.Put it somewhere safe.

The case of the eeePC901 open
You should now be having your first glimpse into the integrated motherboard loveliness of the Asus Eee PC 901.

In order to do the modification, I would recommend that you completely remove the screen section of the Eee PC 901, i.e. separate the two halves of the unit.This makes both the fitting of the touch screen and the reassembly of the screen portion easier.On my first attempt (remember Edison here) I attempted to do the job without removing the two halves and I broke a touch screen.On a later attempt I completely disassembled the Eee PC 901and found the task a lot easier.

Regardless of whether you take my advice on complete dis-assembly, you are going to need to remove the integrated motherboard in order to place the controller board on your Eee PC, so that's our next task.Before the motherboard can be removed, there are some more cables to remove.These are:

  • The cable that connects the screen to the motherboard
  • Cables that connect the microphone element to the motherboard
  • Cables that connect the web-cam to the motherboard
  • The cable that connects the cooling fan
  • The cable that attaches the speakers
  • The Wi-Fi ariel cables.

Connector_web_camConnector_Fan

Connector_Speaker
You can see in this photo the first five of these connectors marked.These must be removed first.These are straight forward male to female plugs, though you may need to use some fine nosed pliers to get a grip of them and pull them out.Remember where they are, because when it comes to reassembly, you don't want to be forgetting these.The Wi-Fi cables attach to the underside of the board, so we won't remove these at this stage.

Connector_Screen
When you come to removing the cables that connect the screen, you are bound to notice that as well as a multi-plug, the screen is also tethered to the motherboard with an earth strap, held in place with a small Philips head screw.This screw is one of two left that are fixing the motherboard to the chassis, its partner is on the right hand side.Remove this also.

Once the cables and screws are removed, we can attempt to remove the motherboard from the chassis.The correct way to tackle this is to lift the motherboard on the right hand side carefully.On the left hand edge, the external VGA port extends out of a hole in the chassis, the motherboard must be lifted upwards and to the left to allow the External VGA port to clear its hole.Do this very gently; remember that the Wi-Fi Ariel cables are still attached to the underside.Once the external VGA port is clear of the case, flip the board over from right to left to expose the underside of the motherboard.

Wi Fi Ariel Connectors
The black and white ariel cables should be obvious now, connecting to the silver object that is the Wi-Fi daughter board.The gold coloured plugs can be pulled out carefully with a pair of fine nosed pliers.They are a push fit item, made of fairly thin metal, so be careful not to crush them in the jaws of the pliers.You can see also that the cables are held in place on the motherboard with a plastic lever clip.A fine tipped flat headed screwdriver can be used to undo the clip.

The motherboard will now be completely free of the chassis.Place it somewhere carefully, preferably where it won't be affected by static electricity.The Ram is covered with an antistatic cover, but the solid state hard drives are unprotected.

Remove the two hinge screws
Next job to tackle is removing the last two screws in the base of the Eee PC 901.These hold the hinges of the screen to the bottom section of the chassis.Removing these and the screen section should now come free from the base.This will make the next stage easier to do.That is to get access to the screen of the EeePC 901.

The screen is made up of two plastic sections; the main part is the section that makes the top of the closed Eee PC 901.Internally this is the section that the internal components mount to.The other section is the fascia or screen surround.Looking at the screen section with the screen itself facing you, there are four rubber bump stops across the top of the screen.These and another two black vinyl dots cover the screw heads we need to get access to.

Remove the six screws from the screen's casing
Take a fine tipped craft knife or very fine tipped precision screwdriver and dig out the rubber and vinyl dots to reveal the screws.They are held in place with double sided sticky.If you are careful, the sticky will remain sticky without any further gluing required during reassembly.I stuck mine to the side of my ready meal container to keep them safe.

This reveals the six screws that you should now remove.We will now be ready to remove the fascia from the screen back.The two halves of the screen assembly are held together with more internal clips.Again this is a job for your thumb nails.Get a nail in to the split between the screens and work the gap.This is a tough job to get the two separated.You can try around the hinges first of all, but keep working around the screen till you get one of the clips to give.Once you get one of the internal clips to separate, you can work from there to completely remove the fascia from the screen back.The screen fascia is made from quite flexible material which can take a little bending as you work.

The Screen Casing Unclipped
Now you should have the open screen in front of you.

Its time to start preparing your screen to accept the touch screen.If you have been using your eee PC at all, the first thing that you need to do is give the screen a thorough clean.Any grease, dust or hairs on the screen are going to be locked in as soon as the screen is fitted.I carefully used ultra-solve and a kitchen towel to clean the screen initially.Then I used the micro pore cloth that came with my Eee PC 901to remove any lint or hair.

The screen with double sided tape applied
Once I was satisfied the screen was clear, I applied double sided sticky tape around the edge of the screen.The best way I found to do this was to apply the tape and then trimmed off any tape that overlapped the edge of the screen.The silver metal surround should be covered.

In other guides that I have seen, the corners only were taped.I tried this on the first occasion and broke a screen.I suspect that this may have contributed to the broken screen.On my successful attempts, I taped the entire surface of the metal surround.This holds the touch screen very securely.When the fascia panel is replaced, this will avoid varying pressure across the glass panel.

Once the tape is in place, give the screen another wipe with the dry micro pore cloth.Dust and hair (especially greyhound hair!) will have been attracted to the surface as you were working.

At this point I think I should mention my second Einstein moment. I have read elsewhere that the anti-glare film that you find on the surface ofTFT screens has a detrimental effect on the quality of image from the screen. As the anti-glare surface is now behind a second glass panel (i.e. the touch panel glass) it's anti glare properties are useless. Some have suggested removing the film is a good idea. Various methods of doing so can be found on the Internet. IU decided to give this a go.

The method I opted for is the wet paper towel method. Basically I soaked paper towels and laid them across the screen surface for a few hours and then attempted to peel the anti-glare coat off. This waspartly effective, but in two places on my screen the anti-glare coat was much better bonded to the screen. in removingit, I removed some of the polarised filter whichis between the anti-glare and the glass of the TFT screen. Polarised filters are essential to you seeing an image through a TFTpanel, so where the coating was stripped, I got white spots onthe screen.Not only that, the anti-glare coat apparently evens out thebrightness across the screen, soI now had a screen with missing sections, anduneven brightness.

Comparing the screen to an unmodified version (Mrs JB's) there was a little improvement in clarity, but not huge amounts. Certainly not enough to justify in my mind the risk you taketo a perfectly good screen. That was my second Einstein moment, and an expensive mistake it was!

Fitting the Touch Panel

The touch panel in place

Next remove the protective film from the glass touch screen panel.If you are careful as you do this, you may get away without having to clean the glass touch panel.Holding the panel to the light, you will be able to see the touch screen film.The touch area does not cover the whole of the panel.The area looks slightly darker as you hold the panel to the light.This darker area you need to line up with the screen so that the panel will be responsive right to the edges of your screen.As it happened with the panels that I had purchased this lined up with the edge of the touch panel sitting flush with the lower edge of the metal surround on the screen.It is worth rehearsing this stage before you peel pack the wax strip on your double sided tape.

Once you are satisfied on the alignment you are aiming for, its time to remove the wax tape on your double sided tape and fit the screen.You want to do this as quickly as possible to avoid dust or hair getting into the gap between the two surfaces.You will probably need to give the surfaces a final wipe with the micro pore cloth that came with the Eee PC 901.

Foam Tape added to touch panel edge for strain relief
Once in place, I decided that I would add some strain relief around the edges of the screen.This is because the fascia is going to be pressing onto the fragile glass touch panel.I decided to attach some foam tape to the edges.The stuff that I used was double sided foam tape that I find useful for attaching circuit boards to surfaces.I did not however remove the wax tape from both sides as I may need to open the screen again in future.That double sided foam is mighty sticky stuff!

 

Now is the scary point of your modification, putting the screens casing back together.If your touch screen is going to break, it's at this point you will hear the dreadful crack.Very carefully fit the two halves of the screens casing together.Start at the hinge point of the screen, carefully routing the cables so that they do not get trapped between the two plastic halves.Once lined up, carefully pinch around the edges of the plastic until you here the internal clips operate.Work your way around the screen until both halves are clipped together.Then replace the screws to secure the screen casing together.Don't over tighten here in case you squeeze the touch screen panel too tightly.

 

If you have reached this stage successfully, and the screen is in tact, you are through the worst of the modification.Have a cup of tea, a cigarette or whatever else you need to chill and settle your nerves.

Fitting the Controller Board

The Touch Panel Controller BoardThe touch screen came with little instruction as to where to mount this, so I spent some time trying out different possibilities before I came to my final solution.The place to place your board is on the underside of the motherboard and you will need some double sided foam to place it there.Attach two pieces of foam to the underside of your touch panel's controller board.Next locate the empty area on the underside of the motherboard between the external USB ports and the solid state hard drive.There is plenty of space here for your controller board orientation wise, the USB in should face towards the cut out for the battery.

The controller board mounted on the underside of the motherboard
The controller board has several outputs and inputs on it.One of these is going to plug in to where the web-cam's cable plugged into the motherboard.Don't worry if you cant remember where this is; it is clearly marked on the motherboard. We will connect this later once the board is in place.Another of the wires (the longest one) is going to attach to the touch screen itself.It is a good idea to route this while you have the board free of the machine. The best way I found to do this, was to route it under the Solid state hard drive and the Wi-Fi card.These are both held onto the motherboard with two screws each.Simply remove the screws and the cards pop up.Slip the cable under them and then refasten the screws.

Reassembly

Turning the board back over, you are ready to reassemble the rest of your Eee PC 901.First of all take the USB in cable of your touch screen controller card and insert it into the web-cam USB port.

Next attach your screen back onto the chassis of your Eee PC 901with two screws.This is simply the reverse of the dismantling procedure.

Now its time to fit the motherboard back into place.Before you do, you will need to attach the web-cam cable onto the connector cable that comes from your Touch screen controller card.When in place this is all going to sit underneath the motherboard neatly out of the way.Coming from the screen, there are two cables that look the same.The longer of the two should be the web cam's cable.The two plugs are shaped so you can't plug them in the wrong way around.

This gets a bit fiddly (hence no photos I both my hands were engaged) but you also need to reconnect the black and white ariel connectors to theWi-Fi card.Once in place, make sure they have clicked together properly by using some pence nosed pliers to squeeze the plugs into their sockets.By now the motherboard will have to be placed into its final position.

Last item to connect up before the board can rest on its mounts is the touch screen itself.Its thin strip connector plugs into the cable that attaches to the controller board.The best place for this lot to rest is underneath the motherboard at the screens connector.The connection can be made with the motherboard in place but lifted slightly.Then tuck the cables under.

The rest of the cables may now be connected to the motherboard, that is:

  • The screen, including earth lead.
  • The microphone cable
  • The fan connector
  • And the speaker connectors.

Then reassemble the rest of the Eee PC 901.Remember to connect up the extra function keys, keyboard and touch pad cables as you go along.

Now we are ready to install some software and test the new touch screen.

Software

The vendor supplied a link to software that controls the screen.However if you go to this link you can download more up to date software and drivers for the touch screen controller.

The download package that EETI supply includes the windows drivers for the touch panel controller and a software bundle called Touchkit which allows you to control the settings for the device. The Touchkit software also includes tools to allow you to calibrate and test the device. As packages go, it is intuitive to use and supplies a good level of function without being overly complicated to operate.

Touchkit tools tab
Once installed, the touch kit software needs to be configured for your screen.The most basic configuration is a four point calibration.Calibration is done by touching the screen with your stylus upon calibration points that are displayed.You hold the stylus to the calibration points until the point disappears.This allows the touch screen controlling software to get an idea as to the orientation of the screen as well as the exact positioning of the capacitive matrix.

Touchkit settings tabWithin the software is the facility to do 4 point, 9 point or 15 point calibration.The more sample points that are calibrated, the more accurate the stylus should be on the screen.However as the screen supplied seems quite linear, I did not find much difference in responsiveness between the different calibrations.I have not yet checked to see if using less calibration points makes the screen more or less responsive. If you wish to change the linearization type to a higher or lower number of calibration points you can do so from the settings menu

The settings menu also gives you access to other options that you may wish to change for your touch panel, for instance how the mouse buttons are emulated. I have mine set so that if I hold the stylus still for a few seconds it emulates a right hand mouse click. This seems to work very reliably.


Touchkit tools tabBefore exiting from the touch kit software you may wish to try the draw test from the tools menu tab.This lets you draw freehand on the screen to test the accuracy of the screen.If all is well you are almost ready to start enjoying your touch screen.


Touchkit_draw_test
One other piece of software that I would consider adding to your system, assuming that you use Firefox that is, is the Grab and Drag add on for firebox.This makes a lot easier the business of surfing web pages using your touch screen stylus.The Grab and Drag add on gives the browser control similar to the I phone.You can grab the web-page and throw it around.

Living with a Touch Screen EeePC901

Using the touchscreen for a week or two now, I could wax lyrical about the difference that it makes to the Eee PC 901. In fairness I won't. To be honest, I don't think my words would do it justice. On a small device such as the Eee PC 901, the extra functionality the touch panel brings, particularly whilst web browsing is incredible. Sofa Surfing becomes a pleasure, the touch kit speeding up idle browsing measureably. The only issue that I can report is that using ordinary screens now has become a real pain; not least because I keep inking them with my pen when I wish to send/recieve my email or when engrossed in a web page.

Diptrace screenshot
Another package that I enjoy using is Diptrace. This is a PCB design package usefull for putting together schematics or for designing circuit boards such as the Pedja Rogic BufferI completed recently. I have found the touch screen so useful for this task, I am now considering buying a 19' wide screen touch screen panel to add to a spareTFT screen that I use at home. I may end up building a digital
drawing board for designing future circuits this way.

Google Sketchup responds well also to the touch screen. Designing on such a small (8.9') screen you would imagine to be fairly limited... Well actually it is a bit, but the touch screen again makes the whole process a lot easier. Using a touch pad accurately on such a small screen is not the easiest, however with the touch panel, simple designs can be put together while reclined on the couch.

ngrc screenshot
NGRC, is a piece of software that shows great promise as being an ideal touch screen application for the Eee PC 901. For those that have not encountered it yet, NGRC is a fantastic remote control application for Windows Media Centers. It installs on the Media Center PC and is accessed through a web browser. From the browser, you can play music, build playlists, see your playlist on the Eee PC 901. Almost all of the other buttons on the Media Center (MCE) remote can be emulated on the Eee PC 901. NGRC is optimised design wise for the I-phone or handheld Playstation screen. I have though managed to hack the code to make the design a bit more suitable for the higher resolution screen on the Eee PC 901. I will write that up into another article as soon as time allows.

I do seem to be developing writers cramp from time to time!