Hello Koray692,
Fusion algorithm BNO055 inside, users could get fusion output.
From "https://www.bosch-sensortec.com/media/boschsensortec/downloads/application_notes_1/bst-bno055-an007.pdf" application note, if you want to use NDOF fusion mode, magnetometer calibration is mandatory immediately after every"power on reset" in order for sensor fusion to create accurate results. After magnetometer calibration by FMC, magnetometer calibration is 3. Then heading value had good accuracy.
... View more