AHRS/Head tracking test with GY-85

I have been dreaming about using a Multiple Degrees of Freedom Sensor in my projects for a long time. It would be great for head tracking in BCI application for example. The 9 DOF sensor from ebay GY-85 has stayed on my desk for 6 months but I haven't got a chance to test it. After I got it running, I wrote this tutorial. Hope you will use it for your great projects.

The detail original tutorial is based on the Sparkfun  9DOF Razor IMU. Mine is a GY-85 and an Arduino Fio. You can port it to any other arduino with ease.

Physically different boards

Similar electrical units

As you can see from the picture above, two configurations are very similar. To get the GY-85 to work , you need to connect it to 5V(prefered) or 3.3V from the Fio is still OK. Then hook up the SCL, SDA as below:

GY-85

Vcc_in -> 5 volt
GND -> Ground/GND
SCL -> A5 
SDA -> A4

Now you can start to follow the original tutorial . When you reach the section: Uploading the firmware> Hardware option, please choose this option:

#define HW__VERSION_CODE 10724 // SparkFun "9DOF Sensor Stick" version "SEN-10724" (HMC5883L magnetometer)

Why? Because the stick is almost the same as the GY-85 ( without the Atmega on it) and the GY-85 comes with the HMC5883L. Push the code to arduino. Data should appear as mentioned in the tutorial. The rest of the tutorial is straight forward.

Do share with me your success stories. Good luck!

ps: another great head tracking project with similar configuration is here