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MotionMC calibration fails (all params have default value)

Question asked by kedopofe kedopofe on May 22, 2018
Latest reply on Jun 10, 2018 by kedopofe kedopofe


I'm currently trying to use the MotionEC library for an E-Compass application, and to calibrate the Magnetometer with the MotionMC library. I'm using an STM32L1-DISCO with an LSM303AGR. My general idea is to run the calibration algorithm for x seconds, then get the calibration parameters, and apply them to the e-compass calculation.


The MotionEC library works perfectly fine but I ran into troubles with the MotionMC library.

At first, I'm running the MotionMC_Update function with the parameters I'm reading from the Magnetometer. After that, I'm calling MotionMC_GetCalParams to get the calibration parameters. But the library is always returning the following default values:

HI_Bias = {0, 0, 0},

SF_Matrix = {{1, 0, 0}, {0, 1, 0}, {0, 0, 1}},


Here is my code (based on the ST examples).


// gets called every 20ms

void doCalibrationStep()
    SensorAxes_t mag_data_uncompensated;


    MMC_Input_t data_in;
    data_in.Mag[0] = (float) mag_data_uncompensated.AXIS_X / 10.0f;
    data_in.Mag[1] = (float) mag_data_uncompensated.AXIS_Y / 10.0f;
    data_in.Mag[2] = (float) mag_data_uncompensated.AXIS_Z / 10.0f;


    data_in.TimeStamp = timestamp * COMPASS_REPORT_INTERVAL;


    // example data_in: Mag = {-64, 5.5, 17.1000004}, TimeStamp = 0


    MMC_Output_t data_out;


    dbg("CalParams X: %f, Y: %f, Z: %f, Quality: %d\r\n", data_out.HI_Bias[0], data_out.HI_Bias[1],
            data_out.HI_Bias[2], data_out.CalQuality);   // everything has default values, no matter how often I run the algo




void doCalibration()
    MotionMC_Initialize(COMPASS_REPORT_INTERVAL, 1);
    char lib_version[200];


    dbg(lib_version);   // here the correct version is printed


    <doCalibrationStep() is called repeatedly in 20ms intervals until x seconds elapsed>


    MotionMC_GetCalParams(&cal_params);   // all parameters are zero


I have absolutely no clue what's wrong. Do I miss something?