micro_ros

Micro-ROS on STM32 micro-controller

This is the unofficial tutorial for setting up the micro-ROS on STM32 micro-controller. I have successfully set up the micro-ROS on the STM32F446RET6 and tested with Ubuntu20.04. Following this tutorial, you could set up it on your own micro-controller, but for the arduino , you might refer some other references. In my opinion, there are the same one and it could be easily to find out the official document on the Github.

Introduction

Features

The Micro-ROS offers seen key features that make it ready for use in your micro-controller-based robotic project:

• Micocontroller-optimized client API supporting all major ROS concepts: Micro-ROS brings all major core concepts such as nodes, publish/subscribe, client/service, node graph, life-cycle, etc. onto microcontrollers (MCU). The client API of Micro-ROS is based on the standard ROS 2 Client Support Library (rcl) and a set of extensions and convenience functions;
• Seamless integration with ROS 2;
• Extremely resource-constrained but flexible middle ware;
• Multi-RTOS support with generic build system;
• Permissive license;
• Vibrant community and ecosystem;
• Long-term maintainability and interoperability;

Architecture

Micro-ROS follows the ROS 2 architecture and makes use of its middleware pluggability to use DDS-XRCE, which is optimized for microcontrollers. Moreoer, it uses POSIX-based RTOS(FreeRTOS, Zephyr, or NuttX) instead of Linux. Dark blue components are developed specially for Micro-ROS. Light blue components are taken from the standard ROS 2 stack.

Requirements

• STM32 micro-controller (ex: Necleo STM32F446R6)

• Linux PC with installed ROS 2

• STM32CubeMX
• STM32CubeIDE

Set up for Micro-controller

STMCubeMX: Generate Basic Code

Using STMCubeMX, we can initialize the pin with in the GUI. Specially, I setup the FreeRTOS, UART4, TIMER1, GPIOand basic pin initialized autonomously. Among them, the FreeRTOS is one of the real time control architecture, and I will use it to control the device in the real time mode. The UART4 is the connection protocol to the PC and it is the very high priority to interrupt. I use two channel of TIMER1 to generate PWM signal and control device. Then the GPIO is used to control the input signal of the switch circuit fabricated by transistor.

Then choose the generate mode with Makefile and do it.

Makefile

we need modify the generated Makefile to include the following code before the build operation:

#######################################
# micro-ROS addons
#######################################
LDFLAGS += micro_ros_stm32cubemx_utils/microros_static_library/libmicroros/libmicroros.a
C_INCLUDES += -Imicro_ros_stm32cubemx_utils/microros_static_library/libmicroros/microros_include

# Add micro-ROS utils
C_SOURCES += micro_ros_stm32cubemx_utils/extra_sources/custom_memory_manager.c
C_SOURCES += micro_ros_stm32cubemx_utils/extra_sources/microros_allocators.c
C_SOURCES += micro_ros_stm32cubemx_utils/extra_sources/microros_time.c

# Set here the custom transport implementation
C_SOURCES += micro_ros_stm32cubemx_utils/extra_sources/microros_transports/dma_transport.c

print_cflags:
	@echo $(CFLAGS)

micro_ros_stm32cubemx_utils

This step, we need to clone the repository into the firmware location. And this repository is aims to ease the micro-ROS integration in a STM32CubeMX/IDE project.

Note: These commands must be run under the Firmware folder

git clone https://github.com/micro-ROS/micro_ros_stm32cubemx_utils.git
cd micro_ros_stm32cubemx_utils
git checkout foxy

Then using the docker, to execute the static library generation tool. Compiler flags will retrieved automatically from our Makefile and user will be prompted to check if they are correct.

Note: These commands must be run under the Firmware folder

sudo docker pull microros/micro_ros_static_library_builder:foxy
sudo docker run -it --rm -v $(pwd):/project --env MICROROS_LIBRARY_FOLDER=micro_ros_stm32cubemx_utils/microros_static_library microros/micro_ros_static_library_builder:foxy

After the installing process, you can find out the following output which means installed successfully.

Summary: 63 packages finished [53.7s]
  40 packages had stderr output: action_msgs actionlib_msgs builtin_interfaces composition_interfaces control_msgs diagnostic_msgs example_interfaces geometry_msgs libyaml_vendor lifecycle_msgs micro_ros_msgs microxrcedds_client nav_msgs rcl rcl_action rcl_interfaces rcl_lifecycle rcl_logging_noop rclc rclc_lifecycle rclc_parameter rcutils rmw rmw_implementation rmw_microxrcedds rosgraph_msgs rosidl_runtime_c rosidl_typesupport_c rosidl_typesupport_microxrcedds_c sensor_msgs shape_msgs statistics_msgs std_msgs std_srvs stereo_msgs test_msgs tf2_msgs trajectory_msgs unique_identifier_msgs visualization_msgs

micro_ros_setup