BNO08x Zephyr Driver

A clean, plug-and-play Zephyr RTOS driver for the BNO08x IMU with Sensor Fusion.

The BNO08x is a powerful 9-axis System-in-Package (SiP) featuring an accelerometer, gyroscope, magnetometer, and a 32-bit ARM Cortex M0+ running Hillcrest Labs' SH-2 firmware. It outputs incredibly stable, pre-calculated quaternions, Euler angles, and activity classifications.

This repository packages the official Hillcrest SH-2 library into a native Zephyr Module, seamlessly handling I2C communication and exposing a clean API for your applications.

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Installation

This driver is structured as a Zephyr out-of-tree module. To add it to your project, simply add it to your west.yml manifest file:

manifest:
  projects:
    - name: zephyr-bno08x
      url: https://github.com/YourUsername/zephyr-bno08x  # Replace with your actual repo URL!
      revision: main

Then, run west update to fetch the module into your workspace.

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Configuration

1. Kconfig (prj.conf)

Enable the module and the required Zephyr I2C subsystem in your prj.conf:

CONFIG_I2C=y
CONFIG_BNO08X=y

# (Optional) Enable floating point print support if you want to print the sensor values
CONFIG_CBPRINTF_FP_SUPPORT=y

2. Device Tree (.overlay)

Add the BNO08x to your board's device tree overlay on the appropriate I2C bus. Make sure to update the pins to match your hardware!

&i2c1 {
	status = "okay";
	clock-frequency = <I2C_BITRATE_FAST>; /* 400kHz recommended */
	pinctrl-0 = <&i2c1_default>;
	pinctrl-names = "default";

	bno086: bno086@4b {
		compatible = "i2c-device";
		reg = <0x4B>; /* 0x4B is the default. Can be 0x4A depending on the SA0 pin */
		label = "BNO086";
	};
};

(Note: The driver currently assumes the devicetree node is labeled bno086 and uses address 0x4B).

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Usage Example

Here is a minimal example of how to initialize the sensor and read the Game Rotation Vector (quaternions) to calculate pitch, roll, and yaw.

#include <zephyr/kernel.h>
#include <bno08x/bno08x.h>

void main(void) {
    printk("Starting BNO08x test...\n");

    // 1. Initialize the sensor
    if (bno08x_init() != SH2_OK) {
        printk("Failed to initialize BNO08x!\n");
        return;
    }

    // 2. Enable the Game Rotation Vector report at 100Hz (10,000 microseconds)
    bno08x_enable_report(SH2_GAME_ROTATION_VECTOR, 10000);

    sh2_SensorValue_t sensor_data;
    bno08x_euler_t euler;

    while (1) {
        // 3. Poll the sensor for new data
        if (bno08x_get_sensor_event(&sensor_data)) {
            
            if (sensor_data.sensorId == SH2_GAME_ROTATION_VECTOR) {
                // Convert raw quaternion into degrees
                bno08x_quaternion_to_euler(
                    sensor_data.un.gameRotationVector.real,
                    sensor_data.un.gameRotationVector.i,
                    sensor_data.un.gameRotationVector.j,
                    sensor_data.un.gameRotationVector.k,
                    &euler, true
                );

                printk("Pitch: %.1f | Roll: %.1f | Yaw: %.1f\n", 
                       (double)euler.pitch, (double)euler.roll, (double)euler.yaw);
            }
        }
        k_msleep(1);
    }
}

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License

This module wraps the original Hillcrest Laboratories SH-2 library. The core SH-2 library and the Zephyr wrapper code are provided under the Apache License 2.0. See the LICENSE file for details.