My next project is a wall mountable 15″ touchscreen tablet and I’m pretty sure I can do it for around £100!
For this I’m using an Acer Travelmate 2413 laptop I picked up for just £10 on ebay. The laptop works absolutely fine, though I got it cheap because both the hinges on the lid are broken so the screen is dangling off the base unit.
Acer Travelmate 2413 with Broken Hinges
I wanted to find a laptop that had at least the same spec as my Dell Mini 9. This one didn’t but for a tenner I thought it would be worth it! The basic spec of the laptop is :
1.5ghz Celeron M Processor
60GB Hard Drive
15″ XVGA Screen (1024 x 768)
It came with Windows XP (urg) so first thing I did was install Ubuntu 11.10 on it with Gnome 3 and tint2. It was so painfully slow! I was worried the hard drive may have been the problem, but fortunately I had a spare 1gb of RAM lying around and swapped out the 256mg RAM card and that fixed the speed.
It is actually surprisingly snappy! Though it only has a 1.5ghz processor compared to the 1.6ghz on the Dell Mini, I think it actually runs alot better. In fact, the speed seems to be on par with my desktop computer so I think it’s going to work great!
I have it set up for dual boot in case I need to use XP for anything.
One feature it lacked that I needed was WiFi. The Travelmate 2413 has a PCMCIA slot which I could have used to install a WiFi card but I needed that slot for something else so I got a handy USB Wifi Dongle for £12.50. Works out of the box in Ubuntu, though needed to install the drivers for it on XP.
USB Wifi Dongle and Serial Port
Next up was the touchscreen. There are 15″ touchscreen kits out there. On ebay there are easy peasy resistive touchscreen kits from Hong Kong for about £60 but I don’t think I could live with a resistive touchscreen. An alternative was to find a capacitive touchscreen kit but all the ones I could find were around $200! Wasn’t willing to pay that much. Luckily I found an IT recycling company near me that has about 25 touchscreens salvaged from the touchscreen game machines you find in pubs. The one I am using is a 15″ General Touch SAW (Standing Acoustic Wave) touchscreen which are very responsive. I got it for only £25 pounds (including the controller) since it was untested. The guys there had no idea how to test it since it didn’t come with the cable that attaches the touchscreen controller to a PC. I was pretty sure I could get it working so went home and investigated the controller.
General Touch 4001 Touchscreen Controller
It was labelled as a General Touch 4001 controller, which is confusing since online I can find a 4001u (the USB version) and the 4001s (the serial version) and so I had no idea whether or not this is the USB or the Serial version, or anything else about the controller for that matter. After investigating the pins on the controller with an oscilloscope I had lying around, I was pretty sure this was a serial version.
Sadly, the Travelmate 2413 doesn’t have a serial port. I could have possibly used a serial to usb adapter, but have had trouble with those in the past so took the more reliable root of getting a Serial Port that fits into the PCMCIA port. Found one for £5 and installed it and it looks to be recognized in both Ubuntu and XP.
Though I still had no idea how to wire the controller to the serial port. I experimented with a few configurations, and although the indicator light on the controller showed that the touchscreen was communication fine with the controller, I couldn’t get the controller to communicate with the serial port. I found a pin out drawing of the controller but still couldn’t figure out how it should be wired.
I emailed General Touch and today replied saying they can provide replacement cables for just $3! Good news! No idea how much the postage is going to be but will let you know.
Oh, one issue with the controller I forgot to mention is that it runs on 12 volts. I have it running on a 12v power supply at the moment, but I’m going to have to find a 12v source on the laptop to tap into in the final build. I’m guessing I can find one around the battery terminal.
Now, how to turn all this into a tablet? It would need a new case so I found this 16″ x 12″ display box on ebay for £22.
This should be big enough to hold all the laptop components after I dismantle it.
I’ve already begun swapping out the glass panel that came with it, and replaced it with the touchscreen panel. Fits nicely.
Display Box with Touchscreen Panel
So far I’ve spent £10 on the laptop, £25 on the touchscreen, £22 on the display box, £5 on the serial port, and £12.50 on the Wifi Dongle.
Total so far = £74.50
So that’s where I am at the moment.
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December 26th, 2011 by sephiroth