Step 14: Program It
Download the attached zip file. Unzip it and move the PS2Keyboard and MatrixDisplay folders to your Arduino libraries directory. This code is compatible with the Arduino IDE 1.0 so if you have an older version please update it before programming the sign. Open up the code in the Arduino IDE, connect your computer to the Ardweeny with the FTDI programming adapter, and upload the sketch. If all is well, a moment later the display will light up with the default text. Unplug the programmer, load some batteries into the battery packs (if you're going to be using battery power), and screw on the back cover. You're all set!
The code for the Ardweeny is based on two open source Arduino libraries: PS2Keyboard (http://www.arduino.cc/playground/Main/PS2KeyboardExt2), and MatrixDisplay, which started out as a thread on the Arduino forum and is now hosted at http://milesburton.com/HT1632_Arduino_%22Matrix_Display%22_Library_for_the_Sure_2416_and_0832. The code uses an interrupt routine to read the raw scan codes coming in from the keyboard and buffer them, then looks up the appropriate character in an array of font glyphs before sending pixel-specific commands to the display panels.