Question about Magnetic Calibration in AN5019

[ck2]

Hi,

I am doing mag calibration according to AN5019 Rev 2.0, Section 5. Seven Parameter Model

I cannot really understand the content in page 22. 

About |A|=1..it says

Can you give me more information about this paragraph? what if we assume that attenuation is 40% or 60%? Does it make any change on computing?? Can we make |A|=10 as we want??
what knowledge should I have before I can understand these?? please let me know it.
Thank you very much

[reyes]

Hi,

No, it is not possible to make |A|=10, even if you assume that attenuation is 40% or 60%, reason is mentioned in the paragraph you sent telling that it is physically impossible to separate out the magnitude of the geomagnetic field strength from the soft iron, reason of why in the NXP software, we always set the determinant of the sift iron matrix |A|=1.

You can download the complete source code and license for the Hard-Iron and Soft-Iron Calibration from: https://www.nxp.com/support/developer-resources/evaluation-and-development-boards/freedom-developmen...

We provide full optimized MCU software with full source code including 10 element magnetic calibration models for Hard-Iron and Soft-Iron on version 7.2 of sensor fusion library via KDSK download from MCUXpresso for FRDM_K64F and FRDM_K22F.

*Please check the ISSDK checkbox when building your KSDK.

Once downloaded you can find specifically the 10 element code can be found in the file magnetic.c in the projects.