micro-ROS Sensors Demo

This demo illustrates micro-ROS capabilities in combination with the STM32L4 Discovery kit IoT node node and Zephyr RTOS. micro-ROS integration with common ROS 2 tools such as RQt are shown in this demo case of use. The used board is an ST development board with a complete set of sensors and communication peripherals:  3-axis inertial units (IMU), environmental sensors (temperature, humidity, and pressure), a time of flight laser ranging sensor, NFC, low-power radio and 802.11 devices.

The vast majority of these peripherals are out-of-the-box supported by Zephyr RTOS. So, by using the micro-ROS + Zephyr port, this demo case will put some of these sensors’ measurements to the ROS 2 world. Concretely, the 3-axis accelerometer data will be published on /sensors/imu ROS 2 topic as a three-position array of 32 bits floating-point data. The range measurement of the time of flight laser sensor will be published on /sensors/tof ROS 2 topic.

Finally, in order to test communications from the ROS 2 world to the embedded board running micro-ROS, the board is subscribed to a simple boolean topic on /sensors/led that will turn a LED on and off.

This demo is also focused on the micro-ROS’s middleware layer where eProsima Micro XRCE-DDS is the default implementation. This software, base on the DDS-XRCE wire protocol, offers to micro-ROS client-server communication with the following characteristics:

  • Multi-transport protocol support (UDP, TCP and Serial).
  • Peer-to-peer communication.
  • Server discovery.
  • Best-effort and reliable communication.
  • Message fragmentation.

This demo aims to be an entry point for further IoT development using the STM32L4 Discovery kit IoT node, Zephyr and micro-ROS. It will also show the ease of use of the micro-ROS development environment for a ROS 2 developer.

Hardware

The following is a list of the hardware needed to reproduce this demo:

How to build and flash the firmware?

  1. Run the builder Docker: 
    docker-compose run stiot_builder

    This demo aims to be an entry point for further IoT development using STM32L4 Discovery kit IoT node, Zephyr and micro-ROS. It will also show the ease of use of the micro-ROS development environment for a ROS 2 developer.

  2. Configure and build the micro-ROS firmware inside the Docker: 
    ros2 run micro_ros_setup configure_firmware.sh sensors_publisher --transport serial-usb
ros2 run micro_ros_setup build_firmware.sh

  3. Connect the board using the STLink USB port

  4. Flash the micro-ROS firmware: 
    ros2 run micro_ros_setup flash_firmware.sh

How to use?

To start the application just two steps are needed:

  1. Connect host USB to your computer. You can disconnect the STLink USB port and modify the board supply jumper on the bottom layer.

  2. Up the Docker Compose:

docker-compose up -d

To stop the application just down the Docker Compose:

docker-compose down

Purpose of the project

The software is not ready for a production use. It has neither been developed nor tested for a specific use case. However, the license conditions of the applicable Open Source licenses allow you to adapt the software to your needs. Before using it in a safety relevant setting, make sure that the software fulfills your requirements and adjust ot according to any applicable safety standards (e.g. ISO 26262).