For those with the 16HMz AT328P version of the SparkFun Razor9DOF board who also want to run the DCM based AHRS code, this may be of interest.

First read Jordi's post for the ArduIMU and Razor6DOF boards:

To remove the 3 highpass filters from the original 9DOF board, C1,C2 and C19 are removed and replaced with shunts (or just shorted). R5,R8 and R16 are also removed. Photo below shows board after modification with capacitor locations marked "J" and resistor locations marked "X".

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  • The board I modified was purchased in January 2010, but has no date marking. Later boards which do not need modification shouldn't have R5,R8,R16 installed. Modified boards will also have shunts (zero ohm resistors) installed in the capacitor locations.
  • Does anyone know if this is required for the boards marked 12/28/09?
  • yea right, on an airplane/heli that's the last thing we want.
  • Thanks, Mark. I'm wondering if the megnetometer can be located far enough from stray magnetic fields on an RC plane. Seems reasonable to me, since David Anderson had good success with a Microstrain 6DOF+mag IMU like this:

    Mu-metal shielding around the big motors might also do the trick.
  • Developer
    Nice work, your mods should work great..
  • No problem Jordi, and thanks for sharing your work. This is really great stuff.

    Also, this was a good SMT rework exercise for me and now I know I can hand solder 0603 parts if I want to use a few on my next PCB design.
  • Developer
    Sorry about that, i sent the alert to sparkfun a little bit late to remove the High Pass Filter.
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