BNO055 spike of Linear Acceleration and Angular Velocity

[Justina]

Dear all,

I'm trying to read the linear acceleration and angular velocity register in NDOF mode by using I2C bus. I think if I just put this sensor on the desk and do not move it, the results should alway be 0. But I can get some spikes. I do not know why. Can you help me to explain it?

I also searched the same problem in this community. I got this BNO055 Linear Acceleration But in my code, there is no "time delay" between reading LSB and MSB.

Here is my results. Thank you very much.

[Justina]

Any one can help me 🤔? Thanks a lot.

[o_o]

Hi Justina:

I see many issues with your design:

1- The L300 inductor limits the peak current of the device. Moreover, there is little capacitance after the inductor to compensate. VDD supply can be filtered with an inductor, but not VDDIO.
2- C314 is only 100nF. The new recommendation from Microchip is 1uF. Our datasheet update will follow soon to reflect this.
3- Logic level clocking is not supported in BNO055. Please remove the SiT1532A1 and replace it with a 32.768kHz crystal circuit.
4- Pin 10 is a digital output. DO NOT CONNECT TO GND. This will create a short circuit.
5- nBOOT_LOAD_PIN needs a connection to the host for future firmware updates. We have planned a firmware update soon that will bring new features and bug fixes.

I understand the logic gate is used for 3.3 to 5V level shifting. Typically, 3.3V will be accepted as a logic '1' by most 5V devices. For level-shifting of the Bus itself, NXP provides a useful application note: https://www.nxp.com/docs/en/application-note/AN10441.pdf

[Justina]

Hello,

can you show me more detail, how can I design nBOOT_LOAD_PIN (pin 4), reset pin (pin 11), if I want to update the firmware version by using I2C?

Is there already an application note for updating firmware?

Thank you.

[o_o · Accepted solution]

We are in the last steps to publish the entire package for the new firmware, including:
-Bootloader Application note
-Bootloader sample code
-Firmware binaries
-New Firmware documentation

The BNO055 datasheet already documents quite well the behavior is the nBOOT_LOAD_PIN and the required connection. See section 3.10

This pin requires a logic low-level at reset to enter the bootloader, otherwise, the application will start.