CLEARPATH Turtlebot4 User Manual page 113

Creating your first node (Python)
This tutorial will go through the steps of creating a ROS2 package and writing a ROS2 node in
Python. For a C++ example, click here. These steps are similar to the ROS2 Tutorial, but focus
on interacting with the TurtleBot 4. For source code, click here.
Note
You can follow this tutorial on either the Raspberry Pi of your TurtleBot 4, or your PC.
Create a workspace
If you do not already have a workspace, open a terminal and create one in the directory of your
choice:
mkdir ~/turtlebot4_ws/src -p
Create a package and node
You will need to create a ROS2 package to hold your files. For this tutorial, we will create a
package called turtlebot4_python_tutorials with a node called turtlebot4_first_python_node.
source /opt/ros/galactic/setup.bash
cd ~/turtlebot4_ws/src
ros2 pkg create --build-type ament_python --node-name turtlebot4_first_python_node
turtlebot4_python_tutorials
This will create a turtlebot4_python_tutorials folder and populate it with a basic "Hello World"
node, as well as the setup and package.xml files required for a ROS2 Python package.
Write your node
The next step is to start coding. For this tutorial, our goal will be to use the Create® 3 interface
button 1 to change the colour of the Create® 3 lightring. Open up the "Hello World" .py file
located at
~/turtlebot4_ws/src/turtlebot4_python_tutorials/turtlebot4_python_tutorials/turtlebot4_first_pytho
n_node.py in your favourite text editor.