Hi all,

In keeping with my previous aim(http://diydrones.com/group/arducopterusergroup/forum/topics/operating-arducopter-without-gps-over-mavlink) of using dead reckoning to follow very short trajectories, I want to use an external AHRS (http://www.microstrain.com/inertial/3DM-GX3-25) with the Ardupilot. I did notice some of the codebase mentioning a secondary AHRS, but I can't seem to find any other discussion/post discussing how to add one to the hardware. Would it have to be via I2C?

Alternately, since this AHRS/IMU can connect via a serial port, how can I use the GPS UART port to read the accelerometer without the codebase going crazy trying to figure out what kind of GPS I've added?

The worst case scenario I'm looking at is that I don't touch Ardupilot's internal AHRS, and just pull the accelerometer data via the serial port.

Any help will be very much appreciated!

Thanks a lot!