Hello

Will a magnetometer (i.e. the one used in a BN-880) be able to deliver an absolute compass reading without preflight calibration (= compass )? 
Or does such a device allways require an initial calibration to deliver absolute directions?

I think I am not sure about the role of the magnetometer... But I expect it to deliver absolute compass readings!?

Thank you.

// Chris

The Magnetometer will deliver direction with reference to Magnetic North (not True North or Grid North).

It can be calibrated by the Calibrate Magnetometer button on the Betaflight Configurator> Setup page and there are instructions to do this by rotation it 360 degrees on all axis.

You can also set the Magnetometer alignment with reference to the craft via the Betaflight Configurator > Configuration> Board and Sensor alignment page.

You can also adjust the Magnetometer declination for the area you live in based on the latest difference between Magnetic North and True North via the the Betaflight Configurator > Configuration> GPS page.

Is it useful? For Betaflight there is not much use in my opinion as it does not offer good autonomous flight modes such as iNav and Ardupilot. I have not used one for 2 years now on a quad because it was always affected by noise.

In terms of accuracy, these are relatively cheap devices and susceptible to noise and you will get much better accuracy if you mount it on a mast high above the noisy components on a quad.

Hello kafie1980

That makes it much clearer to me, what it can do and what the limits in terms of usability and precision are.

I thought about iNav. But the FC, I use, is not supported ( MAMBA F722 APP ). So I am stuck with BetaFlight.

As the device mainly aids autonomous flight as I understand, it will not be of great help for a beginner like me. So I even might unmount it for now.

Thank you for your excellent explanation and your time!!
I appreciate it!
// Chris