Bosch Sensortec BNO055 embedded-hal driver

What is this?

This is a embedded-hal driver for Bosch's Absolute Orientation Sensor BNO055.

It is device-agnostic and uses embedded-hal's Write/WriteRead (for I2C) and Delay traits for its operation.

Uses and re-exports mint's Quaternion for quaternion reading and EulerAngles for Euler angles and Vector3 for sensor readings.

Usage

  1. Add dependency to Cargo.toml:

    bash cargo add bno055

  2. Instantiate and init the device:

    ```rust // ... declare and configure your I2c and Delay implementations ... // let i2c = ...; // let delay = ...;

    // Init BNO055 IMU let imu = bno055::Bno055::new(i2c);

    imu.init(&mut delay)?;

    // Enable 9-degrees-of-freedom sensor fusion mode with fast magnetometer calibration imu.set_mode(bno055::BNO055OperationMode::NDOF)?;

    Ok(imu) ```

  3. Read orientation data, quaternion or euler angles (roll, pitch, yaw/heading):

    rust let quat: mint::Quaternion<f32> = imu.quaternion()?; // or: let euler: mint::EulerAngles<f32, ()> = imu.euler_angles()?;

    Due to the BNO055 firmware bugs, the Euler angles reading shouldn't be relied on. I recommend to stick with quaternion readings and convert them to the Euler angles later if needed.

Details and examples

Device calibration

To calibrate device's sensors for first time:

```rust use bno055::{BNO055Calibration, BNO055OperationMode, BNO055CALIBSIZE};

let bno055 = ...;

// Enter NDOF (absolute orientation) sensor fusion mode which is also performing // a regular sensors calibration bno055.set_mode(BNO055OperationMode::NDOF)?;

// Wait for device to auto-calibrate. // Please perform steps necessary for auto-calibration to kick in. // Required steps are described in Datasheet section 3.11 while !bno055.isfullycalibrated() {}

let calib = bno055.calibration_profile()?;

// Save calibration profile in NVRAM mcu.nvramwrite(BNO055CALIBADDR, calib.asbytes(), BNO055CALIBSIZE)?; ```

To load previously saved calibration profile:

```rust use bno055::{BNO055Calibration, BNO055OperationMode, BNO055CALIBSIZE};

let bno055 = ...;

// Read saved calibration profile from MCUs NVRAM let mut buf = [0u8; BNO055CALIBSIZE]; mcu.nvramread(BNO055CALIBADDR, &mut buf, BNO055CALIB_SIZE)?;

// Apply calibration profile let calib = BNO055Calibration::frombuf(buf); bno055.setcalibration_profile(calib)?; ```

Remapping of axes to correspond your mounting

BNO055 allows to change default axes to meet the chip orientation with actual physical device orientation, thus providing possibility to place BNO055 chip on PCB as suitable for a designer and to match chip's axes to physical axes in software later.

```rust use bno055::{AxisRemap, BNO055AxisConfig}; // ...

// Build remap configuration example with X and Y axes swapped: let remap = AxisRemap::builder() .swapxwith(BNO055AxisConfig::AXISASY) .build() .expect("Failed to build axis remap config");

bno055.setaxisremap(remap)?; ```

Please note that AxisRemap (and the chip itself) builder doesn't allow invalid state to be constructed, that is, when one axis is swapped with multiple of others. For example, swapping axis X with both Y and Z at the same time is not allowed:

rust AxisRemap::builder() .swap_x_with(BNO055AxisConfig::AXIS_AS_Y) .swap_x_with(BNO055AxisConfig::AXIS_AS_Z) .build() .unwrap(); // <- panics, .build() returned Err

Changing axes sign

It is also possible to flip sign of either axis of the chip.

Example of flipping X and Y axes:

rust bno055 .set_axis_sign(BNO055AxisSign::X_NEGATIVE | bno055::BNO055AxisSign::Y_NEGATIVE) .expect("Unable to communicate");

Using external 32k crystal

For better performance, it is advised to connect and use external 32k quartz crystal.

User could enable or disable it by calling set_external_crystal:

rust bno055 .set_external_crystal(true) .expect("Failed to set to external crystal");

Using alternative I2C address

BNO055 allows to change its I2C address from default 0x29 to alternative 0x28 by setting COM3 pin LOW.

To connect to device with alternative address, enable its use by calling with_alternative_address():

```rust // use default 0x29 address let mut bno = bno055::Bno055::new(i2c, delay);

// or:

// use 0x28 address let mut bno = bno055::Bno055::new(i2c, delay).withalternativeaddress(); ```

Change BNO055 power mode

```rust use bno055::{Bno055, BNO055PowerMode}; // Normal mode bno055.setpowermode(BNO055PowerMode::NORMAL)?;

// Low-power mode (only accelerometer being awake) bno055.setpowermode(BNO055PowerMode::LOW_POWER)?;

// Suspend mode (all sensors and controller are sleeping) bno055.setpowermode(BNO055PowerMode::SUSPEND)?; ```

Read chip temperature

Temperature is specified in degrees Celsius by default.

rust let temp: i8 = bno055.temperature()?;

Status

What is done and tested and what is not yet: