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]

Unfortunately not. It sounds like Bosch are discontinuing the part so it looks like my (& your) effort has been a waste of time

" Bosch have told us the part is going EOL at some point and when they have the NRND on a part, they will only support parts that they can continue supplying. I don’t have an EOL date yet, but they can vary from a year or as quick (as we have seen) to a month once announced, it all depends on running business and ability to manufacturer the parts. There is nothing stopping you placing orders for volumes to cover years of production of course, but there is also a last ship date issued with an EOL. I can ask but I don’t believe Bosch will support a part they are going to discontinue. I can ask about trying to arrange time but there would be a cost associated with it, and I would have to check which site has the facilities.

Most manufacturers will only deal through distributors, we do offer the buffer stock, sales, project development etc services for their products which means they focus on design and manufacture of parts so offer them a valuable service. Some do have direct accounts, mainly they are the large manufacturers like the automotive companies, but we do get odd manufacturers taking some of our big customers with a global presence direct."

[BSTRobin]

Hi Digisolve,

BNO055 is not recommended for new design. If your project is new, you can use BHI260AP, which has no discontinued plan.

[Digisolve]

Thanks for the update. Shame this wasn't mentioned earlier as I would not have continued with the BNO055.

With regards to the BHI260AP. This cannot do what I require as it does not have a magnetometer, it only has a Accelerometer & Gyro. Or Am I missing something?

[BSTRobin]

Hi Digisolve,

BHI260AP can be used with BMM150 to realize 9-axis, and BHI260AP has a built-in hub that can run fusion algorithm.

[Digisolve]

Can you be more comprehensive with you reply.

"BHI260AP can be used with BMM150 to realize 9-axis, and BHI260AP has a built-in hub that can run fusion algorithm"

• Is there a dev kit with this confiuration? If yes please send me a link to the page
• Does the fusion software actually exist & will it run on the dev board?