# Magnetometer_Calibration
This repository contains a platformio library and an explanatory jupyter notebook for calculating the hard and soft iron offsets of an magnetometer as descriped in [Calibrating an eCompass in the Presence of Hard- and Soft-Iron Interference](https://www.nxp.com/docs/en/application-note/AN4246.pdf) by NXP.

## Jupyter notebook

Simply run `jupyter notebook` int his folder to start jupyter. Then open the mag_calibration notebook. There you find all informations needed.

## C++ implementation

This implementation depends on Eigen. For platform.io projects you can use [Eigen_Platformio_Header](https://github.com/hobbeshunter/Eigen_Platformio_Header).

Usage:
```C++
#define NO_CALIBRATION_MEASUREMENTS 5000
Eigen::Array<float, NO_CALIBRATION_MEASUREMENTS, 1> mxs;
Eigen::Array<float, NO_CALIBRATION_MEASUREMENTS, 1> mys;
Eigen::Array<float, NO_CALIBRATION_MEASUREMENTS, 1> mzs;
Eigen::Array<float, NO_CALIBRATION_MEASUREMENTS, 1> rolls;
Eigen::Array<float, NO_CALIBRATION_MEASUREMENTS, 1> pitchs;

// Fill measurement arrays

Magnetometer_Calibration mag_cal;
mag_cal.calibrate(mxs, mys, mzs, rolls, pitchs);
Winv = mag_cal.getWinv();
W = mag_cal.getW();
V = mag_cal.getV();
B = mag_cal.getB();
incl = mag_cal.getInclination();
```
## Installing Jupyter
### Setting up Jupyer

	# upgrade packaging tools
	python -m pip install --upgrade pip setuptools wheel

	# install JupyterLab and classic notebook support
	python -m pip install jupyterlab notebook ipykernel
	
	# Register this environment as a Jupyter kernel
	# you need to use your Python environment, e.g. "pioenv" or "rnsenv"
	python -m ipykernel install \
	  --user \
	  --name pioenv \
	  --display-name "Python ~/rnsenv"
	  
#### Example:

	(rnsenv) jlpoole@jp /usr/local/src/Magnetometer_Calibration $   python -m ipykernel install \
		  --user \
		  --name pioenv \
		  --display-name "Python ~/rnsenv"
	Installed kernelspec pioenv in /home/jlpoole/.local/share/jupyter/kernels/pioenv
	(rnsenv) jlpoole@jp /usr/local/src/Magnetometer_Calibration $ 


### Modules:

	pip install numpy pandas matplotlib pyserial cobs msgpack
	pip install --upgrade ipywidgets jupyterlab_widgets widgetsnbextension ipympl

### Restart Jupyter if already running
	
### Start the Jupyter lab:

	jupyter lab
	# The above will open a tab in your current browser