micro-ROS module for Raspberry Pi Pico SDK

Getting Started

Here is a quick way to compile the example given in this repository.

Dependencies

micro-ROS precompiled library is compiled using arm-none-eabi-gcc 9.3.1, a compatible version is expected when building the micro-ROS project. You can specify a compiler path with the following command:

# Configure environment
echo "export PICO_TOOLCHAIN_PATH=..." >> ~/.bashrc
source ~/.bashrc

1. Install Pico SDK

First, make sure the Pico SDK is properly installed and configured:

# Install dependencies
sudo apt install cmake g++ gcc-arm-none-eabi doxygen libnewlib-arm-none-eabi git python3
git clone --recurse-submodules https://github.com/raspberrypi/pico-sdk.git $HOME/pico-sdk

# Configure environment
echo "export PICO_SDK_PATH=$HOME/pico-sdk" >> ~/.bashrc
source ~/.bashrc

2. Compile Example

Once the Pico SDK is ready, clone this repository and compile the example:

git clone -b humble https://github.com/micro-ROS/micro_ros_raspberrypi_pico_sdk
cd micro_ros_raspberrypi_pico_sdk
mkdir build
cd build
cmake ..
make

To flash, hold the boot button, plug the USB and run:

cp pico_micro_ros_right_arm.uf2 /media/$USER/RPI-RP2

3. Start Micro-ROS Agent

Micro-ROS follows the client-server architecture, so you need to start the Micro-ROS Agent. You can do so using the micro-ros-agent Docker:

docker run -it --rm -v /dev:/dev --privileged --net=host microros/micro-ros-agent:humble serial --dev /dev/ttyACM0 -b 115200

Using UART serial communication

To use the UART serial protocol instead of USB (for example, to use micro-ROS in combination with a Raspberry Pi Debug Probe), it is enough to update the # Configure Pico section in the CMakeLists.txt file as follows:

# Configure Pico
pico_enable_stdio_usb(pico_micro_ros_example 0)
pico_enable_stdio_uart(pico_micro_ros_example 1)

What files are relevant?

• pico_uart_transport.c: Contains the board specific implementation of the serial transport (no change needed).
• CMakeLists.txt: CMake file.
• src/main.c: The actual ROS 2 publisher.

How to build the precompiled library

Micro-ROS is precompiled for Raspberry Pi Pico in libmicroros (this directory is gitignored; generate it locally when needed).

Extra interfaces are picked up from library_generation/extra_packages/ and library_generation/extra_packages/extra_packages.repos.

Note: The lucy_msgs package lives in lucy_ros_packages and is imported during the library build. Rebuild libmicroros after changing those definitions.

Native build (no Docker)

Requires a ROS 2 Humble environment with micro_ros_setup, PICO_SDK_PATH pointing at the Pico SDK, the arm-none-eabi-* toolchain, and vcs (from ROS dev tools). From the repository root:

source /opt/ros/humble/setup.bash
cd micro_ros_raspberrypi_pico_sdk
rm -rf firmware   # optional: force a clean micro-ROS workspace
bash library_generation/library_generation.sh

Outputs are written under libmicroros/ (libmicroros.a and libmicroros/include/).

Docker build

The upstream image expects a microros_static_library/ prefix; this repository keeps scripts under library_generation/ at the top level, so set MICROROS_LIBRARY_FOLDER to .:

docker pull microros/micro_ros_static_library_builder:humble
docker run -it --rm -v "$(pwd)":/project -e MICROROS_LIBRARY_FOLDER=. microros/micro_ros_static_library_builder:humble

How to use Pico SDK?

Here is a Raspberry Pi Pico C/C++ SDK documentation: https://datasheets.raspberrypi.org/pico/raspberry-pi-pico-c-sdk.pdf

Purpose of the Project

This software is not ready for 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 it according to any applicable safety standards, e.g., ISO 26262.

License

This repository is open-sourced under the Apache-2.0 license. See the LICENSE file for details.

For a list of other open-source components included in this repository, see the file 3rd-party-licenses.txt.

Known Issues/Limitations

There are no known limitations.