We use the BNO055 in our marine robot, mainly for heading. We write the calibration at the begining and the CALIB_STAT is well at 255.
Our problem is that after some time on the sea, we lose the calibration the system (the system flag drop to 0). We have the same problem when the robot pass under a dock. After we lose the calibration, we can not get again a good calibration.
I read the topic (https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-heading-drift-on-waves/m-p/7681#M...) and It's maybe the same problem.
Do you have a idea why ?
You could refer this ticket: https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-Calibration-Staus-not-stable/m-p/...
And check current accelerometer, gyroscope, magnetometer calibration status.