Tested on:Raspberry Pi 2; Python 2.7; Raspbian pre Jessie
Prerequisites:Raspberry Pi with Raspbian Jessie and internet connection (see steps 1-7 in the Introduction)
Hardware:Odroid-Vu
HDMI A male to HDMI A male cable
Speakers
Logitech PA0086 USB Power Bank
USB to open cable
Coaxial Power Connector 2.5/0.8 mm
Voltmeter
Soldering Equipment
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The PiPad: a simple multimedia Raspberry Pi Pad

The PiPad won’t run as smoothly as a preassembled device, but the components are reusable and the Pad is highly customizable. Using a Raspberry Pi 2 and a fast SDHC card gives the PiPad a pretty good performance. This tutorial was tested with the pretty and low-power Odroid-Vu touchscreen but may work with other touchscreens, too.

Connect the Touchscreen
Follow all tutorials from the Prerequisites. Then, connect the Odroid-Vu with the Raspberry Pi, the HDMI cable for audio and video and the USB cable for the touch interface. Boot and expect the Odroid-Vu to work out of the box, including the touch interface, although keyboard and mouse still need to be connected with the Raspberry Pi for the configuration.

Setup the virtual keyboard Florence

Add the line

at the end of the file.

Florence configuration

  • Click the second button from the top in the leftmost column in the florence interface to open the configuration menu.
  • Under the Tab Behaviour select the input method timer.
  • Click on the Tab Window. Make sure resizable and keep ratio is activated
  • Under the tab layout and extend the Keyboard at least by Navigation keys

Fit and move Florence until size and position are optimal. Then, reopen the configuration, go to the Window-Tab and turn off all checkboxes besides always on top, which should be checked. Reboot afterwards. To Hide/Show Florence, click the keyboard icon in the top-right corner of the screen.
Find more info about the Florence configuration at its sourceforge.

Florence Desktop icon
In case Florence crashes, a simple way for restarting it is necessary. Therefore, create a desktop icon with

and enter

Some may prefer to install the LuaKit browser by now and add an Desktop icon like shown for Florence.

Sound
The Odroid touchscreen has an audio bridge, but it’s necessary to configure the Raspberry Pi to enable it. Open /boot/config.txt with

and add

at the end of the file.
Shut the Raspberry Pi down and plug the speaker cable into the touchscreen. Boot the Raspberry Pi and test the audio with

For problems with the sound, take a look at the Elinux troubleshooting guide.

Video support
Installing the excellent omxplayerGUI from G√ľnter Kreidl gives the Omxplayer a handy GUI for the PiPad. Type in the Terminal

Start the player with

Mobile Power
The PiPad needs at least 1.2A(Screen) + 0.65A(Raspberry Pi) + 0.5A(Wifi) + ~0.5A(audio output) ~= 2.85 Amperes and 5 Volt. Besides the LogiLink Powerbank listed in the hardware section being slightly underpowered, the assembled PiPad runs well. It has an charge of around 18 Amperes, so the PiPad should last for around 6 Hours.
Take a look at the back of the power source which comes with the Odroid-Vu:

PiPad polarisation

The diagram shows the plug is negative on the outside and positive on the inside

Open the 2.5/0.8mm plug and solder a red cable to the inner connector and a black cable to the outhere one:
PiPad plug

Custom touchscreen plug

Then, solder the red cable to the red cable of an open USB plug and the black one to the black one:
Touchscreen power cable

Assembled Touchscreen power cable

Important: Ensure that the polarity of the assembled power cable is equal to the power source which came with the Odroid-Vu with a voltmeter before connecting it to the touchscreen- having it wrong bricks the touchscreen!

Connect the 2 Ampere power out of the USB powerbank with the Raspberry Pi and the 1 Ampere power out with the touchscreen and turn on the USB powerbank.

The PiPad alpha build is now ready to use; making a disk image of the configured SD-card now is a good idea.

Assembled PiPad

Assembled PiPad – alpha build

To Do

  • Emulating a right click on the Odroid-Vu would really improve the usability
  • Florence should be easy to hide
  • Find a way to enable sound for HTML5 Videos
  • Create an enclosure with an better suited power source

Add Ons
For example, implement an browser-based interface for a rc switches system with a browser-based remote control and/or add a microphone for Jasper for voice recognition with Jasper.

Some beautiful PiPads
instructables.com
makezine.com

Links
Odroid-Vu touchscreen: http://www.hardkernel.com/main/products/prdt_info.php?g_code=G140383714860
Florence on Sourceforge: http://florence.sourceforge.net/english/usage.html
LuaKit browser tutorial: http://www.knight-of-pi.org/luakit-a-ultra-lightweight-browser-with-good-video-support/
Elinux touchscreen guide: http://elinux.org/R-Pi_Troubleshooting#Sound
omxplayerGUI documentation: http://steinerdatenbank.de/software/omxplayerGUI_manual.pdf
Creating disk images with gnome-disks: http://www.knight-of-pi.org/sdisk-images-for-complex-rapberry-pi-projects/
Home automation with rc switches: http://www.knight-of-pi.org/cheap-home-automation-with-a-raspberry-pi-controlling-rc-switches-with-pi-switch/
Voice recognition with Jasper: http://www.knight-of-pi.org/voice-control-jasper-raspberry-b-plus/
Webinterface WebIOPi tutorial: http://www.knight-of-pi.org/webiopi-a-simple-but-great-web-api-for-the-raspberry-pi/

Knight of Pi

Johannes Bergs aka Knight of Pi. Diploma in Bioinformatics, some Webdesign and Python coding then. Living in the beautiful city of Vienna.

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