MotionMC calibration fails (all params have default value)

[kedopofe kedopofe]

Posted on May 22, 2018 at 22:59

Hi,

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}},

CalQuality = MMC_CALQSTATUSUNKNOWN

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

// COMPASS_REPORT_INTERVAL = 20

// gets called every 20ms

void doCalibrationStep()

{

    SensorAxes_t mag_data_uncompensated;

    getMagneto(&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

    MotionMC_Update(&data_in);

    MMC_Output_t data_out;

    MotionMC_GetCalParams(&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

    timestamp++;

}

void doCalibration()

{

    MotionMC_Initialize(COMPASS_REPORT_INTERVAL, 1);

    char lib_version[200];

    MotionMC_GetLibVersion(lib_version);

    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?

Thanks

[Miroslav BATEK]

Posted on May 23, 2018 at 21:30

Did you rotate the sensor slowly in a figure eight pattern through 3D space?

Or you can rotate it along each axis.

After this movement you should get the calibration value.

[kedopofe kedopofe]

Posted on June 10, 2018 at 14:21

I did not have time in the last few weeks to look at this issue, but found time today to investigate further.

For users that might encounter this problem:

The problem, was/is that the calibration algorithm has to run quite often before one can read calibration values. Depending on the interval, this takes some time, in my case >10 seconds. I ran the calibration algorithm for a few seconds only and, thus, did not get results.

[Pierre Castera]

Hi, 

I'm facing the same issue. Does anyone resolve this ? 

I'm using a Nucleo F401RE board and a STEVAL -MKI172V1 board  ( dev board for the LSM303AGR sensor). 

 

My hardware is good (I can acces the lsm303agr register) 

 

I init the MotionMc fucntion with a 200ms sample time. I set up a timer for over count every 200ms.I can read the firmware version of the lib 

 

 debug_init(&huart2);
 lsm303agr_init(&lsm303agr,&hi2c1);

 lsm303agr_setup_magnetometer(&lsm303agr);
 lsm303agr_setup_accelerometer(&lsm303agr);

 MotionMC_Initialize(LSM303AGR_MAGNETOMETER_CALIBRATION_SAMPLE_TIME, 1);

 char motion_mc_version[35] = {0};
 MotionMC_GetLibVersion(motion_mc_version);
 printf("motion mc version : %s \n",motion_mc_version);

 HAL_TIM_Base_Start_IT(&htim10);

 

I set up the lsm303agr magnetometer as follow

 

	//0b100001100 = 0x8C
	//COMP_TEMP_EN = 1 -> mag temp compensation enabled
	//REBOOT = 0 -> reboot memory content disabled
	//SOFT_RST = 0 -> soft reset disabled
	//LP = 0 -> low power mode disabled
	//ODR[1:0] = 0x11 -> 100Hz
	//MD[1:0] = 0x00 -> continous mode
	lsm303agr_write_register(lsm303agr,LSM303AGR_CFG_REG_A_M,0x8C);

	//0b00000010 = 0x02
	//OFF_CAN_ONE_SHOT = 0 -> offset cancelation in single mode disabled
	//INT_on_Data_OFF = 0 -> interutp block recognition do not checks data after HI correction to discover the interupt
	//set_FREQ = 0 -> frequency of the pulse is set to every 63 ODR
	//OFF_CANC = 1 -> offset cancelation enabled
	//LPF = 0 -> low pass filter disabled
	lsm303agr_write_register(lsm303agr,LSM303AGR_CFG_REG_B_M,0x02);


	//0b00010000 = 0x10
	//INT_MAG_PIN = 0 -> interupt signal is not driven on INT_MAG_PIN
	//I2C_DIS = 0 -> I2C is enabled
	//BDU = 1 -> protection over wrong data enabled
	//BLE = 0 -> LSB and MSB not inverted
	//SELF_TEST = 0 -> self test disabled
	//INT_MAG = 0 -> DRDY pin is not configure as GPIO Output
	lsm303agr_write_register(lsm303agr,LSM303AGR_CFG_REG_C_M,0x10);

	//set delay to let time to power up
	HAL_Delay(LSM303AGR_DELAY_MAGNETOMETER_POWER_UP);

 

Then I call the following function every 200ms

 

if (token_200ms){

 HAL_GPIO_WritePin(TEST_PIN_GPIO_Port, TEST_PIN_Pin,GPIO_PIN_SET);
 lsm303agr_magnetometer_run_calib(&lsm303agr);
 HAL_GPIO_WritePin(TEST_PIN_GPIO_Port, TEST_PIN_Pin,GPIO_PIN_RESET);

 token_200ms = 0;
}

 

 

 

lsm303agr_status_t lsm303agr_magnetometer_run_calib(lsm303agr_t *lsm303agr)
{
	//increment time count
	lsm303agr->calib_time_count++;

	MMC_Input_t data_in;
	MMC_Output_t data_out;

	// Get magnetic field X/Y/Z
	lsm303agr_read_mag_output_register(lsm303agr);

	data_in.Mag[0] = lsm303agr_mag_val_to_uT(lsm303agr->mag.x);
	data_in.Mag[1] = lsm303agr_mag_val_to_uT(lsm303agr->mag.y);
	data_in.Mag[2] = lsm303agr_mag_val_to_uT(lsm303agr->mag.z);

	// Get current sample time in [ms]
	data_in.TimeStamp = lsm303agr->calib_time_count * LSM303AGR_MAGNETOMETER_CALIBRATION_SAMPLE_TIME;

	// Magnetometer calibration algorithm update
	MotionMC_Update(&data_in);

	// Get the magnetometer calibration coefficients
	MotionMC_GetCalParams(&data_out);

}

// @brief 	TIM callback
// @PAram 	TIM which trig the callback
// @return 	None
//---------------------------------------------------------------------------------------------------------------------
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim){

	if (htim->Instance == TIM10) { //200ms
		token_200ms = 1;
	}
}

 

 

I tried to run the algo more than 1min rotating the sensor slowly but nothing happened I always got 0 for the bias and an Identity matrice for the SF

thanks