When I saw a 7 inch tablet for AUD63 I knew that it would be the cheapest way to get a 800x480 screen for arduino. http://www.warcom.com.au/blog/product-reviews/amicroe-7-tablet-review/
I wanted to use the tablet power supply to power the arduino via the usb connection. The tablet is configured to use an OTG cable which sets the tablet as host. http://forum.xda-developers.com/showthread.php?t=1828032
The next step was the interface program, a very good system is firmata. http://shokai.github.io/ArduinoFirmata-Android/
This was not really what I wanted. I just wanted to use the tablet as a display as in TVout. http://forum.arduino.cc/index.php/topic,51867.0.html
I wrote a small application to use the tablet as a display. My code makes use of the core usb application. http://code.google.com/p/usb-serial-for-android/
The project code is in the download package. I use eclipse indigo with android 3.1 SDK. If you have this or better you can upload the application to your tablet. I send a set of bytes to the tablet to select the drawing function required. I only chose a few but the full range of the android graphics is available. If you don’t have this I published the application in the google play store. It’s free no adds just search “Arduino Usb Android Display”.
The Arduino code is in a library class and has 6 functions.
canvas.setPaint(int wide, byte red , byte green , byte blue, byte style) //wide - width of brush, style 0 = stroke 1 = fill canvas.setText(String text) //text string up to 8 characters canvas.drawLine(int Xstart, int Ystart, int Xstop, int Ystop) canvas.drawRect(int left, int top, int right, int bottom) canvas.drawCircle(int Xcenter, int Ycenter, int radius) canvas.drawText(int Xstart, int Ystart ,int TextSize
Download the package from. http://code.google.com/p/arduino-projects-carl47/downloads/list