magcal-rs

Magnetometer calibration in pure Rust, optimized for embedded use.
Minimal dependencies. Dead-simple API surface. Very much no_std.

This is a Rust port of Freescale/NXP magcal.c by Paul Stoffregen.

Fits hard-iron and soft-iron magnetometer calibration from a batch of raw samples:

corrected = soft_iron * (raw - hard_iron)

There are three solvers available:

• sphere: fits hard iron only.
• axis_aligned: fits hard iron and diagonal soft iron.
• ellipsoid: fits hard iron and full soft iron.

Each tier requires more samples, compute, and memory, but gives increasingly better results.

Usage

use magcal::{MagCal, Solver, SolverTier};

let samples: &[[i16; 3]] = todo!();

// Pick the best tier supported by the sample count.
let cal = MagCal::fit(samples).expect("fit failed");

// Or pick a specific tier yourself.
let cal = MagCal::fit_with(samples, SolverTier::Ellipsoid).expect("fit failed");

// If low on memory, reuse a long-lived Solver, for example a static one.
let mut s = Solver::new();

s.push_sample([100, 200, -150]);
// ...

let cal = s.solve().expect("fit failed");
// Alternatively: solve_sphere / solve_axis_aligned / solve_ellipsoid

s.reset(); // Clear samples and reuse.

// Apply to a fresh raw sample.
let corrected = cal.apply([100, 200, -150]);

Contributing

PRs welcome.

Compatibility

MSRV: Rust 1.63. #![no_std], no alloc, only depends on libm. Builds on stable.

License

BSD-3-Clause; see LICENSE. The upstream magcal.c and matrix.c that src/solver.rs and src/matrix.rs port from are BSD-3-Clause by Freescale Semiconductor, Inc. (2014); the Freescale copyright is preserved verbatim at the top of each ported file. Their original notice is preserved verbatim in NOTICE-UPSTREAM.