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    BMI270: SPI current consumption

    peterl
    New Poster

    Re: BMI270: SPI current consumption

    Good morning.

    Yes, correct, we are using a BMI270 with a BMM150 attached for communication to the Aux interface of the BMI270.

    The current consumptions we see are:

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), not reading the measured data: about 320uA

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), reading the measured BMI270 data  only (via SPI to the micro-processor): about 340uA

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), reading the measured BMM 150 data (via the AUX interface and then transferring it to the micro via SPI), reading the BMI270 data (via SPI to the micro-processor): about 2mA

    Our suspicion is that the transfer of data via the AUX I2C interface is causing this extra power consumption. Is this expected? 

    Thank you very much.

    All the best

    Peter

    Minhwan
    Community Moderator

    Re: BMI270: SPI current consumption

    Hello Peterl, 

     

    Sorry for late response. 

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), not reading the measured data: about 320uA

     (Expected) 

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), reading the measured BMI270 data  only (via SPI to the micro-processor): about 340uA

     (Expected) 

    - BMI270 sampling at 25Hz, BMM 150 in the low-power preset state (normal mode), reading the measured BMM 150 data (via the AUX interface and then transferring it to the micro via SPI), reading the BMI270 data (via SPI to the micro-processor): about 2mA

    Depends on BMM150 setting. Below table is current consumption for each ODR. If you set high accuracy preset or enhanced, 2mA might be understandable. 

    Minhwan_0-1616798363291.png

    AUX interface and BMI270 accel and gyro data shall be independent, you can test accel and gyro from BMI270 is in suspend mode, and only read BMM150 and measure current consumption 🙂 

    Thanks, 

    peterl
    New Poster

    Re: BMI270: SPI current consumption

    Hi Minhwan,

    Thank you very much for your reponse.

    We carried out some more measurements using the BMI270 set-up we have got and also with an analogous set-up which uses the BMI160 in place of the BMI270. The current measurements we got are shown in the attached file.

    The table also contains the measurements you asked about with the accelerometer and gyro in suspend mode.

    We don't understand why reading data from the BMI270 with the SPI interface causes the current increase we see, why the current increases so significantly if we read the magnetometer data via the AUX interface and also why the BMI160 and BMI270 are behaving differently in this respect.

    I'd be very grateful for any suggestions on this. Thank you very much!

    All the best

    Peter

    Current consumption.JPG

    Minhwan
    Community Moderator

    Re: BMI270: SPI current consumption

    Hello Peterl, 

     

    Sorry for late. 

    I'm just curious that BMM150 current consumption in your table. 

    What is the different only BMM150 and BMI270 and BMM150? 

    As I see, BMM150 and BMI270 combination in the middle of your table is 1.5mA ( BMM150 25hz. )

    However, there is 3.5 mA in the end of your table only for BMM150. 

    What is the different? 

    Thank you 🙂 

    peterl
    New Poster

    Re: BMI270: SPI current consumption

    Dear Minhwan,

    Thank you very much for your emssage and questions.

    Each row in the table was measured for a combination of either a BMI270 with a BMM150 or for a combination of a BMI160 with a BMM150. the second column specifies which IMU was used. Each row also uses a BMM150.

    The last row with the current consumption of 3.5mA uses the combination of a BMI160 with a BMM150.

    The row in the middle with a current consumption of 1.5mA uses a combination of a BMI270 with a BMM150.

    For each of these combinations, we tried and measured the current consumpotion for different set-ups as described in the table.

    I hope these comments make sense and are helpful.

    Thank you and all the best

    Peter 

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