In this video, Eric Gregori of EMGRobotics demonstrates how he controls the Freescale Mechatronics board with the Chumby over USB. Starting out with a stock Chumby from Best Buy, Eric steps through how to access the Easter egg hacker screen. Then after installing the Terra Term terminal program on your computer you SSH to the Chumby. From there you can program the Chumby to read sensors, control servos and more.
The source code for the Chumby app is available here.
Check out the slides from Eric’s presentation at the Robotics Summit 2011 for more info on the development of this project.