Introduction

This library allows you to calibrate magnetometers when used with a 3 axis accelerometer. It is designed for use with circuitpython and ulab, but can be used in any python environment where numpy is present.

Dependencies

This driver depends on:

• Adafruit CircuitPython
• Numpy or ulab

Installing from PyPI

On supported GNU/Linux systems like the Raspberry Pi, you can install the driver locally from PyPI. To install for current user:

pip3 install circuitpython-mag-cal

To install system-wide (this may be required in some cases):

sudo pip3 install circuitpython-mag-cal

To install in a virtual environment in your current project:

mkdir project-name && cd project-name
python3 -m venv .venv
source .env/bin/activate
pip3 install circuitpython-mag-cal

Installing to a Connected CircuitPython Device with Circup

Make sure that you have circup installed in your Python environment. Install it with the following command if necessary:

pip3 install circup

With circup installed and your CircuitPython device connected use the following command to install:

circup install mag_cal

Or the following command to update an existing version:

circup update

Usage Example

from mag_cal.calibration import Calibration
from mag_cal.utils import read_fixture

PATH = "../tests/fixtures/cal_data/hj2.json"

with open(PATH) as f:
    aligned, grav, mag = read_fixture(f.read())

calib = Calibration()
calib.fit_ellipsoid(mag, grav)
calib.fit_to_axis(aligned)
calib.fit_non_linear_quick(aligned, param_count=5)

#calib.fit_non_linear(aligned, param_count=3)
for m, g in zip(mag,grav):
    azimuth, inclination, roll = calib.get_angles(m, g)
    print(f"{azimuth:05.1f}° {inclination:+05.1f}° {roll:+04.0f}°")

Documentation

API documentation for this library can be found on Read the Docs.

For information on building library documentation, please check out this guide.

Contributing

Contributions are welcome! Please read our Code of Conduct before contributing to help this project stay welcoming.