BNO055 unreliable calibration & heading readings

[Digisolve]

BNO055 unreliable calibration & heading readings

I'm having difficulty with reliable heading in DNOF mode.  I find it can drifts as much as +/- 20 degrees.

There are many questions I have regarding this. But, as they are all related, I will put them all here in a number list:

1. Power cycling calibration status

I find power cycling effects the accuracy / reliability of the calibration status.

• I calibrate the unit so all 4 calibration status (ACC GYRO MAG SYS) read 3, then save the OFFSET & RADIUS regs to NV storage.
• I then power-down the compass (remove the power)
• I then power-up the compass & restore the OFFSET & RADIUS registers.
• I then check the calibration status & it is no longer calibrated. In some instances NONE of the 4 are 3

2. Power cycling heading reading

 I find power cycling effects the accuracy / reliability of the heading reading.

• I calibrate & save as detailed above.
• I then power-down the compass (removed the power)
• I then power-up the compass in different orientations & restore the OFFSET & RADIUS registers
• I read the heading & it is usually around 0 degrees regardless of the orientation

Always powered-up

I have changed my design to try the compass always powered-up while the battery is connected. This makes an improvement in both cases above, but this is not how I want the design.

I even put the compass into suspend mode on power-down & then back into normal mode at power-up.

3. When / how often should the calibration data to read / restored?

If I have to adopt the always powered-up approach, then the compass will be powered for long periods of time. How often should I read the OFFSET & RADIUS registers into NV storage?

4. Heading drift

I find that the heading drifts. IF I orient the compass in one direction, not change any compass settings, but just turn thru 360 degrees, or move the compass in some random way, the heading can be up to 30 degrees wrong.

5. Absolute heading

I find that the compass does not point north to match my magnetic compass, of my iPhone compass. (NB my magnetic compass & iPhone compass match each other photos attached)

This is was a fully calibrated BNO055 with all 4 CALIB STAT read 3’s

[Digisolve]

Just to clarify will I be able to get heading information from this dev kit like I did from the BNO055 ?

[BSTRobin · Accepted solution]

Hi Digisolve,

Yes, you could get heading information from BHI260AP in DD2.0 like you did from the BNO055.
After you load firmware successfully and set the following sample rate of accel, gyro, mag, you also need to set orientation sample rate.
Set Sample Rate to 25Hz for Acceleromter Passthough(Non-Wakeup)
Set Sample Rate to 25Hz for Gyroscope Passthough(Non-Wakeup)
Set Sample Rate to 25Hz for Magnetomoter Passthough(Non-Wakeup)

See pitch, heading, roll values: