What is the Crosspad?

The Crosspad is a portable tablet device made by the Cross pen company that records the strokes made on it with a special pen. These pages may be downloaded to a computer for OCR or image processing. Links of interest:

What makes the device particularly exciting is that the firmware is stored in 1 meg of flash. This means that it will be possible to upgrade the software on the tablet, possibly replacing it with more useful applications. I envision an OS similar to PalmOS, with Grafiti input, downloadable apps, calendaring, realtime output of the pen strokes and other nifty features. Right now none of this is possible -- the software only stores the strokes and bulk uploads them to the computer, so it is not possible to use the Crosspad as a graphics tablet, yet.

Cool, it works with Linux!

Not right out of the box. Of course the software only supports Windows, so some reverse engineering was necessary. After doing much of the hard work I found Jun-ichiro itojun Hagino's code for *BSD that had information on the protocol and format of the data. A little bit of porting and I have produced a Perl module that handles the details of retrieving the current contents of the Pad's memory.

Now I am writing a module that will decode the "Ink" files that are produced and generate Postscript/GIF/Perl callbacks from the data stream. Right now it will draw the strokes with Perl/Tk. Slow and painful, but working.

Show me the code!


I want to thank Itojun for documenting the protocol and specifications as well as he did. They made the job of writing the module much, much easier than the tedious amount of reverse engineering and reading of the Java SDK that would have been required otherwise.

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