Freescale Semiconductor Xtrinsic MAG3110 Magnetometer RD4247MAG3110 RD4247MAG3110 User Manual

Freescale Semiconductor

11

 

— Observe how the Fit Error % field’s values increases, in going from the 10-element model to 

the 4-element model, as a less-complete calibration model is used.

The 7-element model simplifies the inverse soft-iron matrix to a diagonal matrix with zero 
off-diagonal elements. The calibration parameters are the three hard-iron coefficients, the three 
soft-iron matrix coefficients, and the geomagnetic field strength.

The 4-element model further simplifies the inverse soft iron matrix simplifies to a unit matrix. The 
calibration parameters are the three hard-iron coefficients and the geomagnetic field strength.

10. Deliberately jam the eCompass by bringing it close to a spurious magnetic field (such as a 

notebook hard disc or a magnet from a desktop-telephone speaker).

— The Fit Error % field’s value increases and the number of green calibration bars drops from four 

to one and are replaced by the red magnetic warning icon, as shown in the following figure.

— The frame’s status field displays Jammed. Rotate to re-measure geomagnetic field.

11. To unjam the eCompass, do either of the following:

— Move the eCompass away from the jamming source and rotate the evaluation board to obtain 

new measurements of the geomagnetic field for calibration.

The Fit Error % value decreases and the number of green bars increases up to five, as the 
jammed calibration measurements are replaced by newer measurements.

— Click the Reset button to immediately discard all calibrations and rotate the evaluation board 

to capture new calibration data.