An all-in-one package for building a local MicroROS workspace supporting ROS2 and flashing a ROS2 node on a Raspberry Pi PICO.

These instructions were put together to make setting up a new PICO microcontroller and integrated into a larger ROS2 framework connected to a host server as painless as possible. Installation of this package has been tested with native Ubuntu 22.04 and Windows 11.

Installation

These instructions should work for ROS2 distributions Foxy, Humble, and Iron. These install steps have been successfully tested with a WSL (Ubuntu 22.04 on Windows) session running on Windows 11 in adition to native Ununtu 22.04 OS.

If any problems occur, the Raspberry Pi company has a detailed setup manual for further help.

Additional steps: WSL

If using WSL to interface with physical usb devices, you will need to set up USB pass-through access.

Install Micro-ROS

Make sure your packages are up-to-date.

sudo apt-get update & sudo apt-get upgrade -y

Create the microROS workspace with a ready-to-use micro-ROS build system. This will download any required cross-compilation tools and build the apps for your system.

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

# Create a workspace and download the micro-ROS tools
cd $HOME
mkdir -p micro_ros_ws/src
cd micro_ros_ws
git clone -b $ROS_DISTRO https://github.com/micro-ROS/micro_ros_setup.git src/micro_ros_setup

# Update dependencies using rosdep (note that this assumes you've already installed it through the standard ROS2 install steps)
sudo apt update && rosdep update
rosdep install --from-paths src --ignore-src -y

# Install pip
sudo apt-get install python3-pip

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

• Note: Be aware of "End-Of-Life" distributions. If using ROS2 Foxy which reached its EOL phase Summer of 2023, an additional parameter of --include-eol-distros is needed when performing the rosdep command

  rosdep install --from-paths src --include-eol-distros --ignore-src -y

Create the firmware workspace that targets all the required code and tools

# Create firmware step
ros2 run micro_ros_setup create_firmware_ws.sh host

Finally create the microROS agent package and source the workspace

ros2 run micro_ros_setup create_agent_ws.sh
ros2 run micro_ros_setup build_agent.sh
source install/local_setup.bash

Install Pico SDK

Now let's get the latest stable release of the Pico SDK installed and configured:

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

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

• Note: The Pico SDK installation downloads a handful of submodules for TinyUSB which could take up quite a bit of space on your PC. If optimization isn't a concern, continue with the installation. Otherwise, you can delete folders from the pico-sdk/lib/hw path and remove the board types you won't be using. Be sure to keep at least these two folders: pico-sdk/lib/hw/bsp/rp2040 pico-sdk/lib/hw/mcu/raspberry_pi

You may get a warning that the TinyUSB submodule isn't initialized yet. If so, navigate to the pico-sdk directory and initialize the submodule:

cd $HOME/micro_ros_ws/src/pico-sdk
git submodule update --init

Install Pre-Compiled MicroROS Pico libraries

Once the Pico SDK is ready, compile the example:

git clone https://github.com/micro-ROS/micro_ros_raspberrypi_pico_sdk.git $HOME/micro_ros_ws/src/micro_ros_raspberrypi_pico_sdk
cd $HOME/micro_ros_ws/src/micro_ros_raspberrypi_pico_sdk
mkdir build
cd build
cmake ..
make

Flashing Code

To flash code onto a Pico, hold the reset button on the Pico and plug in the USB cable. The .uf2 file that gets created in the micro_ros_raspberrypi_pico_sdk/build subdirectory can be moved to the RPI drive by either clicking and dragging, or with the command:

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

Start MicroROS Agent

Assuming the Pico is connected on dev/ttyACM0, pass that in as an argument for the serial communication method.

ros2 run micro_ros_agent micro_ros_agent serial --dev /dev/ttyACM0

If access to the port is denied, you may need to allow read/write access and add yourself to the tty and dialout groups (necessary for communicating with USB peripheral devices).

sudo chmod a+rw /dev/ttyACM0
sudo usermod -a -G dialout $USER
sudo usermod -a -G tty $USER

Contributors:

• Jonathan Shulgach (jshulgac@andrew.cmu.edu)

This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.