micro-ROS 笔记

Installing ROS 2 and the micro-ROS build system

bash
# Source the ROS 2 installation
source /opt/ros/$ROS_DISTRO/setup.bash

# Create a workspace and download the micro-ROS tools
mkdir microros_ws
cd microros_ws
git clone -b $ROS_DISTRO https://github.com/micro-ROS/micro_ros_setup.git src/micro_ros_setup
rosdep update && rosdep install --from-paths src --ignore-src -y

# Build micro-ROS tools and source them
colcon build
source install/local_setup.bash

Creating a new firmware workspace

bash
# Creating a FreeRTOS + micro-ROS firmware workspace
ros2 run micro_ros_setup create_firmware_ws.sh freertos olimex-stm32-e407

# Creating a Zephyr + micro-ROS firmware workspace
ros2 run micro_ros_setup create_firmware_ws.sh zephyr olimex-stm32-e407

Configuring micro-ROS firmware

bash
ros2 run micro_ros_setup configure_firmware.sh [APP] [OPTIONS]

The options available for this configuration step are:

--transport or -t: udp, serial or any hardware-specific transport label
--dev or -d: agent string descriptor in a serial-like transport
--ip or -i: agent IP in a network-like transport
--port or -p: agent port in a network-like transport

In this tutorial, we will use a Serial transport (labeled as serial) and focus on the out-of-the-box ping_pong application located at firmware/freertos_apps/apps/ping_pong. To execute this application with the chosen transport, run the configuration command above by specifying the [APP] and [OPTIONS] parameters as below:

bash
ros2 run micro_ros_setup configure_firmware.sh ping_pong --transport serial

Building the firmware

bash
ros2 run micro_ros_setup build_firmware.sh

Flashing the firmware

bash
ros2 run micro_ros_setup flash_firmware.sh

Creating the micro-ROS agent

bash
# Download micro-ROS-Agent packages
ros2 run micro_ros_setup create_agent_ws.sh

# Build step
ros2 run micro_ros_setup build_agent.sh
source install/local_setup.bash

# Run a micro-ROS agent
ros2 run micro_ros_agent micro_ros_agent serial --dev [device]

TIP: you can use this command to find your serial device name: ls /dev/serial/by-id/*

Testing the micro-ROS app

bash
source /opt/ros/$ROS_DISTRO/setup.bash

# Subscribe to micro-ROS ping topic
ros2 topic echo /microROS/ping

bash
source /opt/ros/$ROS_DISTRO/setup.bash

# Subscribe to micro-ROS pong topic
ros2 topic echo /microROS/pong

bash
source /opt/ros/$ROS_DISTRO/setup.bash

# Send a fake ping
ros2 topic pub --once /microROS/ping std_msgs/msg/Header '{frame_id: "fake_ping"}'

Standalone build system tools

bash
ros2 run micro_ros_setup component --help

创建自己的 STM32 板子下的 micro-ROS

执行 "Installing ROS 2 and the micro-ROS build system" 步骤

bash
mkdir f407_ws
cd f407_ws
git clone -b $ROS_DISTRO https://github.com/micro-ROS/micro_ros_setup.git src/micro_ros_setup
rosdep update && rosdep install --from-paths src --ignore-src -y
colcon build

bash
source install/local_setup.bash
ros2 run micro_ros_setup component stm32cube

使用 STM32CubeMX / STM32CubeIDE 创建 STM32 Project，并根据要求配置好工程。
修改代码文件 freertos.c 文件。

c
#include "usart.h"

#include <cmsis_os.h>
#include <rcl/rcl.h>
#include <rcl/error_handling.h>
#include <rclc/rclc.h>
#include <rclc/executor.h>
#include <uxr/client/transport.h>
#include <rmw_microxrcedds_c/config.h>
#include <rmw_microros/rmw_microros.h>
#include <std_msgs/msg/int32.h>

bool cubemx_transport_open(struct uxrCustomTransport * transport);
bool cubemx_transport_close(struct uxrCustomTransport * transport);
size_t cubemx_transport_write(struct uxrCustomTransport* transport, const uint8_t * buf, size_t len, uint8_t * err);
size_t cubemx_transport_read(struct uxrCustomTransport* transport, uint8_t* buf, size_t len, int timeout, uint8_t* err);

void * microros_allocate(size_t size, void * state);
void microros_deallocate(void * pointer, void * state);
void * microros_reallocate(void * pointer, size_t size, void * state);
void * microros_zero_allocate(size_t number_of_elements, size_t size_of_element, void * state);

void subscription_callback(const void * msgin)
{
    const std_msgs__msg__Int32 * msg = (const std_msgs__msg__Int32 *)msgin;
    printf("Received: %d\n", msg->data);
}

void StartMicroRosTask(void *argument)
{
  // micro-ROS configuration
  rcl_ret_t ret;
  ret = rmw_uros_set_custom_transport(
      true,
      (void *)&huart1,
      cubemx_transport_open,
      cubemx_transport_close,
      cubemx_transport_write,
      cubemx_transport_read);

  rcl_allocator_t freeRTOS_allocator = rcutils_get_zero_initialized_allocator();
  freeRTOS_allocator.allocate = microros_allocate;
  freeRTOS_allocator.deallocate = microros_deallocate;
  freeRTOS_allocator.reallocate = microros_reallocate;
  freeRTOS_allocator.zero_allocate = microros_zero_allocate;

  if (!rcutils_set_default_allocator(&freeRTOS_allocator)) {
    printf("Error on default allocators (line %d)\n", __LINE__);
  }

  // micro-ROS app
  rcl_publisher_t publisher;
  rcl_subscription_t subscriber;
  std_msgs__msg__Int32 msg;
  rclc_support_t support;
  rcl_allocator_t allocator;
  rcl_node_t node;

  allocator = rcl_get_default_allocator();

  // create init_options
  ret = rclc_support_init(&support, 0, NULL, &allocator);

  // create node
  ret = rclc_node_init_default(&node, "cubemx_node", "", &support);

  // create publisher
  ret = rclc_publisher_init_default(
      &publisher,
      &node,
      ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int32),
      "cubemx_publisher");

    // create subscriber
    ret = rclc_subscription_init_default(
        &subscriber,
        &node,
        ROSIDL_GET_MSG_TYPE_SUPPORT(std_msgs, msg, Int32),
        "/cubemx_subscriber");

    // create executor
    rclc_executor_t executor;
    ret = rclc_executor_init(&executor, &support.context, 1, &allocator);
    ret = rclc_executor_add_subscription(&executor, &subscriber, &msg, &subscription_callback, ON_NEW_DATA);

  msg.data = 0;
  /* Infinite loop */
  for(;;)
  {
    rclc_executor_spin_some(&executor, RCL_MS_TO_NS(100));
    ret = rcl_publish(&publisher, &msg, NULL);
    if (ret != RCL_RET_OK) {
      printf("Error publishing (line %d)\n", __LINE__);
    }

    msg.data++;
    osDelay(10);
  }
}

编译烧写固件到 STM32 板子上
执行 "Creating the micro-ROS agent" 步骤
执行命令开启 micro-ROS agent

bash
ros2 run micro_ros_agent micro_ros_agent serial -b 115200 --dev /dev/ttyCH341USB0

查看 STM32 在 ROS2 上发布信息

bash
ros2 topic echo /cubemx_publisher

发布消息

bash
ros2 topic pub --once /cubemx_subscriber std_msgs/msg/Int32 '{data: 1}'

一些问题解决

注意，需要在工程中添加 micro_ros_stm32cubemx_utils 目录下的 extra_sources子目录中的一些 .c 代码文件。


extra_sources/microros_time.c
extra_sources/microros_allocators.c
extra_sources/custom_memory_manager.c
extra_sources/microros_transports/dma_transport.c or your transport selection.

Linux 下普通用户使用串口

bash
sudo usermod -a -G dialout $(whoami)
sudo chmod a+rw /dev/tty*

Linux 下使用 CH340 USB转串口

bash
# 驱动地址:https://www.wch.cn/download/CH341SER_LINUX_ZIP.html

# # CH340系列串口芯片无法识别
sudo apt-get remove --purge brltty

mcu -serial-> micro_ros_agent 是通的，micro_ros_agent --> ROS2 不通（即ROS2上查看不到 micro-ROS的节点）。

查看 ROS_DOMAIN_ID 环境变量。

ROS 2 用于通信的默认中间件是 DDS。在 DDS 中，让不同的逻辑网络共享物理网络的主要机制称为域 ID。同一域的 ROS 2 节点可以自由地发现消息并相互发送消息，而不同域的 ROS 2 节点则不能。默认情况下，所有 ROS 2 节点都使用域 ID 0。为避免同一网络上运行 ROS 2 的不同计算机组之间的干扰，应为每个组设置不同的域 ID。

bash
env | grep ROS_DOMAIN_ID

解决方法 1：取消 域ID 环境变量

bash
unset ROS_DOMAIN_ID

解决方法2：在 MCU 代码中设置 域ID

C
rcl_node_options_t node_ops = rcl_node_get_default_options();
node_ops.domain_id = 10;
RCCHECK(rclc_node_init_with_options(&node, "my_node_name", "", &support, &node_ops));

如果在未安装 Docker 环境下编写代码，需要编译 micro-ROS的库。

找到一台有 Docker 的电脑/虚拟机。
在命令行中执行下面的指令。

bash
git clone -b humble https://github.com/micro-ROS/micro_ros_stm32cubemx_utils.git
docker pull microros/micro_ros_static_library_builder:humble && docker run --rm -v ./:/project --env MICROROS_LIBRARY_FOLDER=micro_ros_stm32cubemx_utils/microros_static_library_ide microros/micro_ros_static_library_builder:humble

然后拷贝 micro_ros_stm32cubemx_utils 目录到对应的STM32工程目录下即可。