A few weeks ago at the inPulse hackathon, Eric and Alex helped me modify a watch to get at the debug serial port. I added a sensor board based on the InvenSense IMU-3000, a 3-axis gyroscope. A microcontroller on the sensor board communicates with the IMU-3000 over I2C and sends a rotation matrix representing the orientation of the watch to the inPulse debug serial port. From there, I used Trammell Hudson's Teatime code to draw a 3D wireframe of an arrow, with the camera perspective given by the rotation matrix retrieved from the sensor board.

Used with an auxillary accelerometer, the IMU-3000 performs sensor fusion to output a stable rotational frame about all three axes (yaw, pitch, and roll). With an accelerometer, you can only really measure pitch and roll, and when you add a compass to measure yaw, you still have much lower frequency response than with a gyroscope. The takeaway here is, gyroscope plus sensor fusion opens the door to some pretty cool applications you can't do with other sensors.

So in addition to showing off the possibilities of adding sensors to the inPulse, this is a demo of the gyro+accel sensor fusion made possible by the InvenSense Embedded MotionApps Platform- you can learn more about that on the InvenSense developer's website. (I work at InvenSense on the MotionApps platform.)

The inPulse watch is a pretty cool platform for building wearable sensor demos, hopefully you'll see some more soon!

Source code on github

Very neat - blogged about it on our site.
Next: create an excercise app for inPulse