BNO055 pitch direction after startup (fusion mode)
I'm using the BNO055 in fusion mode to detect pan (yaw) and tilt (pitch). Calibration is OK and also loading the calibration results at startup (in config mode) seems to be fine. The pitch readout is from 0 to 65535 and the 0 value is when levelled. That seems to be OK too.
However, the direction of the pitch seems to be dependent on the position of the sensor when powering on. As the sensor leans forward at boottime, then pitch direction and range are different as when the sensors leans backwards at boottime. I added 2 images to make clear what exactly happens.
It is not 100% reproducable, but this problem makes it difficult(in fact: impossible) to use the BNO055 sensor to read tilt values.
Re: BNO055 pitch direction after startup (fusion mode)
I see 2 issues in your problem description: 1- The pitch is a signed value, from -180 to +180. 2- Euler angles are relative to the mounting orientation of the sensor. If the sensor is mounted to the bottom or top side of the PCB, BNO055 will automatically adjust the output. If the pitch angles are significant (as in your pictures), then the BNO055 can change the reference frame for Euler angle output. Please use the Quaternion output instead, and convert it back to the pitch and yaw values that your application needs. The quaternion output has no discontinuities and uses a fixed reference frame.