I have looked at two AHRS for the razor. One of then doesn’t appear to have a means to calibrate but also appears to claim it isn’t needed. The nuisance, the yaw setting (compass) didn’t seem to behave the way I would have expected.
It appeared that the north-south axis wasn’t 90degrees with the east-west.
Now, I found an EMI meter (so-called) for my iPhone and … well I should have known, I was trying to calibrate the compass while the sensor sat on the top of my laptop.
There was beer involved.
Mental note to oneself: Use a longer usb cable and find a spot half a meter at least from the laptop.
Still, I am happier with the other version of the AHRS as the on screen behavior seems to equate (mostly) with the behavior of the sensor. Still needs calibration so still a little work.