The [http://mchobby.be/data-files/datasheet/ht16K33v110.pdf Holtek HT16K33] chip used in all of our backpacks communicates using the common I2C bus. Linux and the Pi both have native support for I2C, but you'll need to run through a couple quick steps from the console before you can use it in Python.
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If you are running Occidentalis and are familiar with Terminal commands, then the description below will be sufficient.
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If not, then to learn more about how to setup I2C with either Raspbian or Occidentalis, then take a minor diversion to this Adafruit Tutorial: http://learn.adafruit.com/adafruits-raspberry-pi-lesson-4-gpio-setup/configuring-i2c