BNO085-ROS2-Node

A ROS2 Compatible node that interfaces with the BNO085 IMU sensor via python. The node publishes the linear acceleration (gravity compensated) and angular velocity on /imu/data.

Build with colcon build in root of repository. Source ./install/setup.sh. Run with ros2 run bno085 bno085_publisher.

Requirements

TODO: Added Requirements.txt

The node communicates with the BNO08x via i2c on the Raspberry Pi and Python. The required software/libraries to run this code:

• Adafruit_CircuitPython_BNO08x
• Adafruit-extended-bus
• Adafruit_Blinka
• RPi GPIO

I2C Setup

The Raspberry Pi hardware I2C implementation doesn't handle clock stretching due to a bug. This is a problem when using the BNO085 (and it's cousins it appears, the BNO55 and BNO080) because it causes the crashes when the sensor is communicating with the Pi's programs.

There are 2 recommended options across the internet:

• Slow the I2C Clock
  • This didn't work well for me, as continues to crashed the script, or if too low wouldn't even detect the sensor.
  • Also follow the suggestion in this hookup guide and setting the Clock faster @400KHz made it worst and crashed more quickly
• Configure and Use software I2C instead which supports clock stretching at the cost of a slight increase in CPU usage.
  • Using this guide in addition to the previous link, I update the code the use the software I2C interface with SDA on GPIO23, and SCL on GPIO24 and giving the bus id 3

As an extra: config.txt on ubuntu on the Pi is located in /boot/firmware/config.txt instead of /boot/config.txt

Test Setup

• Platform: Raspberry Pi 4
• OS: Ubuntu 22.04.2 LTS
• ROS: ROS2 Humble
• Python: 3.10.6