BNO055 ODR 2

[PB_FHBi]

Hello Bosch,

i was reading this Post as a solution: 

"The closest standalone sensor you could compare the BNO055 to would be the BMA280, BMG160 and BMM150. The performance values will differ, but you may refer to their respective datasheet for an overview of their functional description.

In particuar, you will find in BMA280's datasheet that the sampling rate of filtered acceleration data is always twice the selected bandwidth (i.e. BW = ODR/2), and in BMG160's datasheet you will find a table with the ODR corresponding to each available filter bandwidth.

Available configurations of raw sensor modes of the BNO055 are listed in chapter 3.5 of its datasheet."

But when i put the USB BNO055 Stick in ACCONLY MODE and choose 1000 Hz low pass filter, i measure an Output Data Rate about 160Hz.

The BMG160 Datasheet is not really comparable with this. On page 44 stands for a filter  BW 523Hz the ODR is 2000Hz. I was trying but i couldn't access 2000Hz Data Rate via I2C to BNO055 in ACCONLY MODE. Is the 2000Hz Sample Rate only for the internal MCU and BNO055 sends the filtered Data with a lower frequency?

Edit: Is the Filter Analog or Digital?

[o_o]

I am a bit confused by your question... Let's break it down:

Is the Filter Analog or Digital?

The MCU in BNO055 does not filter the raw data. Accelerometer and gyroscope ASICS each contain a 2nd degree digital filter.

The BMG160 Datasheet is not really comparable with this. On page 44 stands for a filter  BW 523Hz the ODR is 2000Hz. I was trying but i couldn't access 2000Hz Data Rate via I2C to BNO055 in ACCONLY MODE.

The BMG160  is the gyroscope. Data is not available in ACCONLY MODE. (as the name suggests, only accelerometer data is available in this mode). Indeed the gyroscope and accelerometer have different filter bandwidth and data rates selections.

But when i put the USB BNO055 Stick in ACCONLY MODE and choose 1000 Hz low pass filter, i measure an Output Data Rate about 160Hz.

How do you measure this, with DD2.0 ? I know the BNO055 USB stick has some limitations. Internally, the data rate is indeed 2kHz, but this could simply be a limitation of the USB protocol. Have you tried an Application board 2.0 with shuttle board ?

[PB_FHBi]

Thanks for the quick answer. I Used the Data Logging by DD2.0 with Timestamp and calculate the ODR of the collected Data.
I got no Shuttle Board, i am using a STM32F103RB on a own Board and i tried to get Data as fast as possible via I2C but when I analyze it with my Logic Analyzer, i see gaps about 150-200 us between Data from Register. In the Datasheet i read about clock stretching from BNO055, so i tried to verify my Data with the USB-Stick.

I am interested to know, if there are Limitations of reading raw ACC Data about 2kHz via I2C? (to know if my Software has a mistake included)

[o_o · Accepted solution]

Indeed with the clock stretching, 2kHz data readout is not possible, even though the data is internally available at 2kHz.
Unfortunately clock stretching cannot be avoided.

If you are interested in raw data, may I recommend BMX055 instead? The BNO055 sensor was never designed to provide raw data at high rate.

[PB_FHBi]

Yes that's what i was thinking too. I would have chosen a different sensor for this, but BNO055 is already integrated on the board and i am working through my Bachelor Thesis with this fixed board design ...