Altitude Issue with PixRacer

Hi Guys,

Today I discovered the following:

Weather was -15oC (5oF), wind was 30km/h, gust 39km/h, cold weather.

The issue is that we are inside at 23oC and we go outside with the quad, temperature difference is for sure very high…

REL-ALT is at 0m when I arm the vehicle, I fly it, land it, REL-ALT is now -4m.

It does all sorts of issues like GEOFENCE and RTL are not working correctly, quad stays in the air because altitude is not good…

If I land it on the first try (when REL-ALT is - 4m) I re-arm it, now altitude is good (0m) and id doesn’t drift anymore…

So I suspect that BAROMETER temperature is not implemented correctly with the PixRacer.

As per MS5611 Barometer Datasheet we can read:

Every module is individually factory calibrated at two temperatures and two pressures. As a result, 6 coefficients necessary to compensate for process variations and temperature variations are calculated and stored in the 128-bit PROM of each module. These bits (partitioned into 6 coefficients) must be read by the microcontroller software and used in the program converting D1 and D2 into compensated pressure and temperature values.

Is this part Temperature compensated in the firmware?



There is temperature compensation available on master:

Thanks, will try tomorrow, keep you posted.

@LorenzMeier Just to be sure, you recommend to update firmware using MASTER in QGC?