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    High current consumption of BNO055

    High current consumption of BNO055

    mmurty
    Member

    Hello,

    We are developing a wearable device which contains the BNO055 part.

    I am presently experimenting with it and noticed that the suspend mode current consumption of the device doesn't match with the datasheet. The device datasheet mentions 40uA as the maximum current consumption whereas practically measuring it I get it around 80uA. I don't suspect the driver as I am using the driver provided by BOSCH on this github page: https://github.com/BoschSensortec/BNO055_driver and I follow all the steps demonstrated in the bno055_support.c file.

    Please help me out with this.

    18 REPLIES 18

    Hi Moderator,

    I checked with the hardware team and they made it clear that the 0 ohm resistor on BL_IND pin was not populated on any of the boards while we did the current measurements. Also as per your recommendation, they have increased the capacitance on pin 9 from 100nf to 1uf still the result remains unchanged and the board consumes around 168uA in suspend mode.

    Please let me know your comments on this.

    Hi mmurty,

    Sorry if I am a a bit running out of ideas here, but in the past I have seen the issue that the host MCU had an internal pull-up/pull-down which would cause current draw on the INT PIN. This is the only output pin of the BNO055.
    The only other active pins, are the i2c port, and the crystal port.

    o_o

    Hello,

    So is this problem with a specific batch of chips or all the new chips have similar problem? Because earlier in this thread I could see the other bosch team could achieve 40uA power consumption in suspend mode on the BNO055 shuttle board.

    And is there any kind of workaround or firmware upgrade which can fix this issue?

    Further I would also like to know whether you recommend this part for future products because we are already facing issues with this one in the existing product while calibrating the sensor and with power consumption. We are also planning new products with the same sensor so if you have any alternative please suggest.

    Thanks for your reply.

    Hello @mmurty,

     

    I appreciate you sharing you concerns over the BNO055 and let me reassure you that the part is still current and recommended for new designs. We are actually looking forward to bring new features on the BNO055 with firmware update, which is taking a bit longer than expected.

     

    Let me answers your questions:

    So is this problem with a specific batch of chips or all the new chips have similar problem? Because earlier in this thread I could see the other bosch team could achieve 40uA power consumption in suspend mode on the BNO055 shuttle board. And is there any kind of workaround or firmware upgrade which can fix this issue?

    We have faced similar issue in the past (~160uA using our application board). In our case, it was not related to a specific batch of chips or firmware, but rather an issue with the host MCU. The GPIO pins have internal pull-down which causes extra current consumption. This is why, in the screenshot that Alan shared, multimeter is connected to the GND pin. (GNDIO and GND pin are tied together on the shuttleboard).  We have confirmed the MCU pull-down current to be the issue on our end with a custom firmware disabling the pull-down.

     

    [...]if you have any alternative please suggest.

    If power consumption is a concern, BNO055 would not be my recommendation. The minimum voltage is 2.5V, and current consumption is 12mA, making it an ~30mW solution for a 9DOF rotation vector. The BHI160 + BMM150 solution operating voltage is 1.8V and current consumption is 1.55mA, making it ~2.8mW solution, about 1/10th of the power used by BNO055. The sensor hub does not contain flash however, which requires a more complicated driver on the host side and increases boot time, but the gains in power consumption are very significant.

     

    o_o

    Hi,

    By Host MCU do you mean an external application processor reading data from BNO055 or the Cortex-M0 processor which is internal to BNO055?

    I think I got confused when you replied earlier.

    Please clarify.

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