Hello,
I am working on the calibration of the BNO055. Instability of system calibration status in current firmware has been discussed before in other posts. I have found basically two answers for this:
Case 1: It is suggested to ignore the system calibration value as long as the calibraton status of the other sensors are 3 (https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-Calibration-Staus-not-stable/td-p...).
Case 2: Only the status of the system calibration should be considered after reusing a calibration profile (https://community.bosch-sensortec.com/t5/MEMS-sensors-forum/BNO055-Sensor-Calibration-reuse-magnetom...).
Considering the above cases, these are my questions:
1. Usually after a POR, all calibration status = 3, but sometimes the sensors calibration status = 3 and sys remains 0. What should be done in this case? Can the data be trusted if sys = 0 after a POR?
2. Unlike case 1, I found that when running in NDOF mode, if sys = 0, the data should be ignored: “The reason is that system cal '0' in NDOF mode means that the device has not yet found the 'north pole', and orientation values will be off The heading will jump to an absolute value once the BNO finds magnetic north (the system calibration status jumps to 1 or higher) (taken from: (https://learn.adafruit.com/adafruit-bno055-absolute-orientation-sensor/device-calibration?view=all).”
2.1 So, is the data reliable when sys = 0 in NDOF mode, or not? Considering that case 1 says the opposite.
2.2 Is the data reliable when sys = 0 when using a non-fusion mode?
3. I am writing the calibration profile to flash memory to reuse later. Considering case 2, after writing the calibration offsets and radius to the BNO055, to verify that the calibration profile was written correctly,
3.1 is it enough to verify that sys = 3?
3.2 This is not contradictory with case 1, where it is said that the value of sys is not reliable?
4. In the case where sys = 3, but other sensors = 0, how can this happen? Don't the other sensors need to be fully calibrated for sys = 3?
5. The BNO055 Quick Start Guide says that it is highly recommended to check the magnetometer's calibration status periodically to recalibrate it when = 1. Does this apply when running in non-fusion mode, as well as in fusion mode? I understand that in fusion mode the autocalibration runs in the background, which makes me conclude that it is not necessary to check the calibration status.
Thank you in advance for the clarification!
