BerryIMU

A pure-rust library for interfacing with BerryIMU v3.

This supports accelerometer and magnetometer readings via i2c, and accelerometer and gyroscope readings via SPI. Settings are fixed, and i2c only works on linux. Pull requests to add more functionality are welcome.

Example

This will print out the tilt-compensated heading via i2c:

use std::error::Error;
use std::f64;
use std::thread;
use std::time::Duration;

use berryimu;

pub fn main() -> Result<(), Box<dyn Error>> {
    let mut accelerometer = berryimu::i2c::Accelerometer::new_from_address("/dev/i2c-1")?;
    let mut magnetometer = berryimu::i2c::Magnetometer::new_from_address("/dev/i2c-1")?;

    loop {
        let (acc_x, acc_y, acc_z) = accelerometer.read()?;
        let (mag_x, mag_y, mag_z) = magnetometer.read()?;

        // Normalize accelerometer raw values.
        let acc_x_norm =
            (acc_x as f64) / ((acc_x * acc_x + acc_y * acc_y + acc_z * acc_z) as f64).sqrt();
        let acc_y_norm =
            (acc_y as f64) / ((acc_x * acc_x + acc_y * acc_y + acc_z * acc_z) as f64).sqrt();

        //Calculate pitch and roll
        let pitch = acc_x_norm.asin();
        let roll = -((acc_y_norm / pitch.cos()).asin());

        // Calculate the new tilt compensated values
        // The compass and accelerometer are oriented differently on the the BerryIMUv1, v2 and v3.
        // This needs to be taken into consideration when performing the calculations.
        // X compensation
        let mag_x_comp = (mag_x as f64) * pitch.cos() + (mag_z as f64) * pitch.sin();
        // Y compensation
        let mag_y_comp = (mag_x as f64) * roll.sin() * pitch.sin() + (mag_y as f64) * roll.cos()
            - (mag_z as f64) * roll.sin() * pitch.cos();

        // Calculate heading in degrees
        let mut heading = 180.0 * mag_y_comp.atan2(mag_x_comp) / f64::consts::PI;
        if heading < 0.0 {
            heading += 360.0;
        }

        println!("{heading:.2}");

        // Sleep for 25ms
        thread::sleep(Duration::from_millis(25));
    }
}

See also the examples/ directory.