iTouch / iPhone
I could not resist to build the system using perfect multitouch display of iPod Touch (3G, 8MB, OS v 3.0, ~$200).
What is needed
1. Jailbroken iPhone or iPod Touch. Please find current tools for your version of iPod or iPhone device. There are many sites on the net were you can find detailed instruction how to jailbreak the device. Here is an "official" site of the developers http://blog.iphone-dev.org/ .
2. 30 pin connector . I got mine from http://www.chargeconverter.com/shop/connector.htm (S type) for $2.39
3. Software to upload my program to iPod. I'm using either WinSCP (to use with Windows OS) or Cyberduck (for Mac OS). Both programs are free.
4. DRO.app software available from this site.
How to use
1. Connect serial output described on microcontroller page to iPod /iPhone connector. The 3.3V, Rx, and ground pins are used (in this version Tx pin (to toggle fast/slow modes is not used, because I realized that this option is not actually needed, system enters fast mode at startup; also the modes can be switched with the button located on the microcontroller board).
Here is 30-pin connector pinout: http://pinouts.ru/PortableDevices/ipod_pinout.shtml . pin 11 (serial GND) should be connected to pin 1 (GND), pin 13 (Rx) should be connected to Tx pin of the board, pin 1 (GND) goes to GND of the board, pin 18 (3.3 V power) goes to VDD of the board (top-left on the first picture on microcontroller page). The board will get power from iPod / iPhone battery, to have iPod / iPhone powered from external power supply connect also USB pins of USB power supply (pins 16, 23, 25, 27).
2. Upload DRO.app to the application folder. here is how it looks with WinSCP: Note: the program must be downloaded to the "Application" folder of the iPod (not to the "User" ), otherwise serial port will not be accessible and you will see "Unable initialize UART" message after startup.
3. Reset iPod / iPhone by simultaneous pressing "power" and "home" buttons of the iPod for 5 seconds, or just "power off" and "power on" the device with holding "power" button for several seconds.
You should be able to see icon on the springboard.
Here are screenshots, the program can be tested without scales, just select "test" for the output, random numbers will be sent to the screen.
To adjust size of the labels place two fingers on the screen and spread them apart (to zoom in) or squeeze your fingers together (to zoom out). To zero an output tap the label with one finger, or cross several labels with one finger.