This repository contains AHRS example for estima crate. It was tested with GY-86 and ESP32-C6-Zero boards.
Running at 160 MHz (no FPU), it achieves approximately 19 Hz sampling. Connections are simple, just plug one PCB into another as on an image above.
| ESP32 | GY-86 |
|---|---|
| GPIO22 | VCC_IN |
| GPIO21 | 3.3V |
| GPIO20 | GND |
| GPIO18 | SDA |
| GPIO19 | SCL |
GY-86 board combines MPU6050, HMC5883L, and MS5611 on a single PCB board.
A magnetometer provides XYZ components of the magnetic field. Before using that data we need to calibrate the sensor. In an ideal world all measurements would be on a centered sphere, but in the real one we have soft and hard-iron biases.
Having a magnet around "pulls" measurements from the center, creating a hard iron bias. A piece of magnetic material like iron would stretch or distort the magnetic field.
We will use simple magnetometer model for calibration: h = A(h_m - b). Calibration parameters A and b could be estimated by fitting an ellipsoid to raw measurements and finding ones that turn distorted ellipsoid into perfect sphere.
Parameters are stored in MagCalibration, magnetic reference is stored in AccelMagMeasurement.
You need to adjust them for your location and sensor.