Facebook
Google
GitHub
Linkedin
I am using LSM303C 3D compass module to measure accelerometer and magnetometer. Ideally I would like to know a compass heading which would tell me which direction I am facing, however, I am still not unsure how would you do that. I have tried using FusionCompass library which takes the cross product of my accelerometer and magnetometer data, but the results are not quite as expected.
My accelerometer data seems fine - when the device is flat on the surface, I am reading(converted to G):
X=0g
Y=0g
Z=1g
Is there any way to confirm whether the magnetometer data is correct?
My debug window:
As I rotate my device 90 degrees clockwise or counter clockwise, I expect the heading to change by approximately 90, but it does not.
Considering the fact that the accelerometer data is correct, the magnetometer data should be fine too therefore I believe there might be a problem with the way the formulas compute the compass heading in the fusioncompass functions.
My accelerometer data seems fine - when the device is flat on the surface, I am reading(converted to G):
X=0g
Y=0g
Z=1g
Is there any way to confirm whether the magnetometer data is correct?
My debug window:
C:
void magxl_test() {
if(magxl_init() < 0) {
if(I2C1_IsDeviceReady(MAG_SLAVE_ADDRESS7, 5) == HAL_OK) {
#ifdef DEBUG_PRINT
debug_printf("MAG responding to Address!\n");
#endif
}
else {
#ifdef DEBUG_PRINT
debug_printf("MAG not responding\n");
#endif
}
while(1);
}
uint8_t reg = WHO_AM_I_A;
FusionVector3 accelerometer = {
.axis.x = 0.0f,
.axis.y = 0.0f,
.axis.z = 0.0f,
};
FusionVector3 magnetometer = {
.axis.x = 0.0f,
.axis.y = 0.0f,
.axis.z = 0.0f,
};
xyzData_t magdata; //create a variable named magdata which contains structure x y and z
xyzData_t xldata[32];
int dataCount;
float curent_time=HAL_GetTick();
while(1) {
while(!magxl_mag_dataReady());
magxl_mag_getData(&magdata);
dataCount = magxl_xl_getFIFOData(xldata);
// Calculate offset for each axis and substract from reading
float offset_X= (X_MAX + X_MIN)/2;
float offset_Y= (Y_MAX + Y_MIN)/2;
float offset_Z= (Z_MAX + Z_MIN)/2;
#ifdef DEBUG_PRINT
debug_printf("\n\n>>magnetometer x: %i, y: %i, z: %i\n", magdata.x, magdata.y, magdata.z);
debug_printf("\n Accelerometer x: %i, y: %i, z: %i\n", xldata->x, xldata->y, xldata->z);
#endif
//Convert to G value
//Z-Axis
//Z@1G = 15500
//Z@-1G = -16800
//Z Centre Point = (15500 - 16800) / 2 = -650
//Z Range = 15500 + 16800 = 32300
//G Per Sample Z = 2.0G /32300 = 0.00006191950464f
// 2G divided by full scale for each axis
GPerSample.z = 2 / (Z_MAX - Z_MIN);
GPerSample.y = 2 / (Y_MAX - Y_MIN);
GPerSample.x = 2 / (X_MAX - X_MIN);
// Calculate offset for each axis and substract from reading
float zG = (GPerSample.z * (xldata->z));
float xG = (GPerSample.x * (xldata->x));
float yG = (GPerSample.y * (xldata->y));
#ifdef DEBUG_PRINT
debug_printf("\n DEBUG****Accelerometer in G: X: %f , Y: %f, Z: %f\n", xG, yG, zG);
#endif
magnetometer.axis.x = ((float)magdata.x);
magnetometer.axis.y = ((float)magdata.y);
magnetometer.axis.z = ((float)magdata.z);
accelerometer.axis.x = ((float) xldata->x);
accelerometer.axis.y = ((float) xldata->y);
accelerometer.axis.z = ((float) xldata->z);
#ifdef DEBUG_PRINT
// debug_printf("\n\n>>magnetometer x: %i, y: %i, z: %i\n", magdata.x, magdata.y, magdata.z);
#endif
float heading = FusionCompassCalculateHeading(accelerometer, magnetometer);
debug_printf("\theading: %f\n", heading);
float last_time=HAL_GetTick();
HAL_Delay(50);
debug_printf("time= %.2f\n", last_time);
}
}As I rotate my device 90 degrees clockwise or counter clockwise, I expect the heading to change by approximately 90, but it does not.
Considering the fact that the accelerometer data is correct, the magnetometer data should be fine too therefore I believe there might be a problem with the way the formulas compute the compass heading in the fusioncompass functions.
