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    BMX055 Magnetometer direction calculation

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    New Poster

    BMX055 Magnetometer direction calculation

    Hi, I am trying to use the BMX055 as a compass, but am having some issues. I am reading the X,Y and Z axis information but I was expecting with the device flat, I would get '0' on 2 axis and then the other axis value changes when moved. What I am getting is angles on all axis and just by rotating the devices I get X and Y both changing. In the data sheet it refers to an API, but I can only find code for displaying the raw data which I already have working. I would be grateful if you can send me any application notes to help me solve this problem.

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    Community Moderator

    Re: BMX055 Magnetometer direction calculation

    Hi,

    Thanks for your inquiry.

    BMX055 is a 9-axis sensor that includes 3-axis accel, 3-axis gyro and 3-axis magnetometer. In order to get a tilt compensated eCompass, you need to use both accel data in the unit of g and magnetometer data in the unit of uT from BMX055. In order to make the heading angle be immune to the external magnetic interference field, you need to use gyro data in the unit of degree per second or radian per second. Therefore, you need sensor fusion algorithm to get eCompass from BMX055.

    Please download BSXLite sensor fusion library at https://www.bosch-sensortec.com/software-tools/software/sensor-fusion-software/ and integrate it into your firmware. Then you can get the eCompass right away from BMX055.

    Thanks.

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    New Poster

    Re: BMX055 Magnetometer direction calculation

    I have downloaded the BSXlite software, but I can't see what is required. There is precompiled software for cortext M3 and M4, but I am writing the software for a different processor and need to write everything from scratch. Is there a document stated how the data is manipulated from the raw data to get a true direction?

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    Community Moderator

    Re: BMX055 Magnetometer direction calculation

    Hi,

    After you download BSXLite there are two PDF files for BSXLite API and integration guide. You only need to define your processor's I2C read/I2C write/Delay three functions. Then you should be able to use the library.

    Thanks.

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    New Poster

    Re: BMX055 Magnetometer direction calculation

    The closest I can find in the pdf's is from page 17 of the 'Library integration guide', but this doesn't state how the raw data is manipulated to get the true heading. Please specify the area of the pdf's you refer to which shows how the raw data is manipulated.

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