Connect Create® 3 to Raspberry Pi® 4 and set up ROS 2 Humble

Before you start

Attention

These directions are written for someone with experience with embedded Linux and basic embedded computers.

It is highly recommended to read through the following documents before beginning:

How to install Ubuntu Server on your Raspberry Pi¹ - official Canonical documentation
Installing ROS 2 on Ubuntu Linux¹ - official Open Robotics documentation

Step-by-step

Download and install the appropriate version of the Raspberry Pi Imager on your computer.
Open the imager and under operating system, select "Other general-purpose OS" then "Ubuntu" and finally, "Ubuntu Server 22.04 LTS (64-bit)".
Insert your microSD card into your computer and under storage in the Raspberry Pi Imager, select your microSD card.
It's recommended to customize advanced options for the image before flashing it. To do it, either click on the gear icon, if visible, or press "ctrl + shift + x" keyboard shortcut ("command + shift + x" on MacOS). Advanced options include enabling SSH, setting a unique username and password, and configuring a wireless LAN. It is recommended to uncheck the "Eject media when finished" box in advanced options so you can edit the necessary files in the following steps without re-inserting the SD card.
Once all options have been selected, click the "WRITE" (or "NEXT") button to write the image to your SD card.
In the system-boot partition, edit config.txt and add dtoverlay=dwc2,dr_mode=peripheral at the end of the file.
In the system-boot partition, edit cmdline.txt to add modules-load=dwc2,g_ether after rootwait.
In the system-boot partition, edit the network-config executable to optionally add information about your Wi-Fi connection, and also add the following under ethernets
```
        usb0:
            dhcp4: false
            optional: true
            addresses: [192.168.186.3/24]
```
For convenience, here's a copy of this file. Be sure to remove the .txt extension. Note that the robot uses the default IP address of 192.168.186.2 on its usb0 interface. Please note also that after initial boot, editing network-config in the boot partition will not do anything; instead, you will need to edit /etc/netplan/50-cloud-init.yaml. After editing that file, you will need to run sudo netplan generate followed by sudo netplan apply to update your network configuration.
If you would like your Raspberry Pi® 4³ to communicate with the Create® 3 over its USB-C®² port (and not just to power it), be sure that the USB/BLE toggle on the robot's adapter board is set to the USB position.
Insert the microSD card into the Raspberry Pi® 4³, and then use a USB-C®² to USB-C®² cable to connect the Raspberry Pi® 4³ to the Create® 3. A photo of this connection can be found here. The first boot may take a few minutes. (It may help to have a monitor and keyboard set up in case of any trouble on the first boot.)

Attention

If you are new to ROS 2 and would like to utilize the turtlesim tutorials, it necessary to install a desktop environment to do this. We have had success with xubuntu which can be installed with the following command: sudo apt install xubuntu-desktop. Please see the Ubuntu docs for more details.
Log in with the default username and password (ubuntu/ubuntu), change your password, and then change your locale to be one that uses UTF-8. For example, in the US, type
```
sudo apt update
sudo apt install locales
sudo locale-gen en_US en_US.UTF-8
sudo update-locale LC_ALL=en_US.UTF-8 LANG=en_US.UTF-8
export LANG=en_US.UTF-8
```
Recommended: follow the procedure to Setup NTP on this compute board so the Create 3 can sync its clock.
Optional: Run timedatectl and see if System clock synchronized: says yes. If not, you may want setup NTP on your raspi so the clock stays accurate. To do so, specify some NTP servers for time syncronization. Edit /etc/systemd/timesyncd.conf (sudo nano /etc/systemd/timesyncd.conf) to have the below contents, then run systemctl restart systemd-timesyncd.service to load the new NTP server configuration.
```
[Time]
NTP=ntp.ubuntu.com
FallbackNTP=0.us.pool.ntp.org 1.us.pool.ntp.org
```

Then, execute the following blocks of commands to install ROS 2⁴:

sudo apt update && sudo apt install -y curl gnupg2 lsb-release build-essential git cmake

then

sudo curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(source /etc/os-release && echo $UBUNTU_CODENAME) main" | sudo tee /etc/apt/sources.list.d/ros2.list > /dev/null
sudo apt update

then

sudo apt install -y ros-humble-desktop
sudo apt install -y ros-humble-irobot-create-msgs
sudo apt install -y build-essential python3-colcon-common-extensions python3-rosdep ros-humble-rmw-cyclonedds-cpp

finally

echo "source /opt/ros/humble/setup.bash" >> ~/.bashrc

At this point, we recommend setting your default RMW. The RMW you set here has to match the RMW on your robot, which can be found from its Application Configuration page. More detail on RMW can be found here. Depending on your robot's RMW implementation, type one of the following:
```
echo "export RMW_IMPLEMENTATION=rmw_cyclonedds_cpp" >> ~/.bashrc
```
or
```
echo "export RMW_IMPLEMENTATION=rmw_fastrtps_cpp" >> ~/.bashrc
```
Log out and log back in. Once you do, test things out with a ros2 topic list. A full Create® 3 API description can be found here.

Attention

If you are using CycloneDDS, your Raspberry Pi® may be running with multiple network interfaces (usb0 to talk to robot and wlan0 to talk to laptop). You will need to export a path on the Raspberry Pi® to an xml config file that registers those interfaces in the CYCLONEDDS_URI. See CycloneDDS Multiple Network Interfaces.

Ubuntu is a registered trademark of Canonical Ltd. ↩↩
USB-C® is a trademark of USB Implementers Forum. ↩↩↩
Raspberry Pi® is a trademark of Raspberry Pi Trading. All other trademarks mentioned are the property of their respective owners. ↩↩↩
ROS 2 is governed by Open Robotics ↩