Temperature calibration trouble


I am trying to do temperature calibration a pixhawk 2.1 board, but am not having much luck.

I am following the directions here for offboard calibration:


I am using the offboard technique. First I cold soak the board for about 30 minutes @ -30C. Then I raise the temperature up over the next 30 minutes to +70C. At this point I power down the pixhawk and run the python script.

The resulting output is very strange.

First attempt is here:


17_54_03.ulg.pdf (309.0 KB)

Why is there no data in the middle of the log? This attempt had a much faster ramp on temperature, so the log is shorter.

Second attempt here:


log001.ulg.pdf (1.4 MB)

Why is the log only 20 minutes? I had the system in the test chamber for at least an hour. Was data lost due to removing the power? How do I shut the board down to close the log file properly?

Why are the graphs over such a small temperature range, and why is that range different for each sensor?

Without the calibration I get massive errors on the accelerometers in the cold (-5C or so). “sensors status” shows a 1G discrepancy between some of the axes.

Also, does SENS_EN_THERMAL have any usage?

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