Saturday, February 28, 2015

A Raspberry Pi tablet

Since the year 2008 the world was "invaded" with all kinds of smartphones and tablet mostly based on Android or IOS, but all of them follow the same pattern. You can watch movies on them, you can play games on them or browse the web, but that is kind of all you can do with them.
I like to think different, I wanted a device that can do more, so when Raspberry Foundation announced a board that has a CPU and can run an operating system that let you control some input and output ports, I realized that it is now possible to build a device that can do what any other tablet can do, but also, what any other tablet cannot do- like controlling relays, or process data from some sensors like a pressure sensor, even turn it into a portable oscilloscope.

I also wanted that my tablet as standalone as possible, to be able to use it anywhere without thinking at battery life. So I mounted two solar panels on the back of the device. 

However, here I failed, becase the efficency of those solar pannels is simply too low to charge two 3500 mAh batteries, so the best way to charge the tablet is with two 5v mini usb chargers.
The building process started by the aquisition of the Raspberry Pi model B board.

 Now the latest version is model 2 wich has a quad core CPU and can run Windows 10.
The second main component was the touchscreeen, which i bought from Ebay

The touchscreen also came with a board that has two analog image inputs, one vga port and one hdmi port. For this device i choosed the hdmi posrt as the connection between the raspberry board and the screen. As for the touchscreen, i connected it to one of the two usb ports of the Pi.

You can see in this image the touchscreen usb module
The third main component was the batteries, wich i ordered from a local electronic shop. Basically they were some of those usb solar chargers for mobile phones. Bellow is a picture with them disassembled

With all those main components, i installed the raspbian os on a sd card instructions here and with the screen connected and the two batteries on the back, i turn the device on.

The touchscreen was not connected yet, becase the kernel of the Raspbian OS need to be recompiled in order to recognize touch input. You can find nstructions for that by searching "raspberry pi egalax touchscreen" on google.
The case of the device was made from the case of a playstation 3 console.

The batteries were then placed on top of the boards

The final thing i did was to cover the sides with that grey tape to give it a nice look.
Here are some pictures with the device in action controlling two relays, that turn on/off two light bulbs

You can see the atablet is connected to the internet via a RJ45 cable, which is not often found on tablets.

But what make this unique is the input/output ports, which are not present on any tablet in the market.