DEV Community: naguballa77

ROS2 Publisher Node.

naguballa77 — Fri, 31 Oct 2025 18:56:37 +0000

Hey everyone 👋
In my previous blog, I shared how I started exploring ROS2 Humble using Turtlesim.
Now, I’ve moved one step ahead — by creating my own C++ node that publishes data inside ROS2.

This post will walk you through everything I did — step by step — so you can do the same on your system.

⚙️ Step 1:

Creating a New Package

Inside your workspace:

cd ~/ros2_ws/src
ros2 pkg create --build-type ament_cmake pkg_2

What this does:

Creates a folder named pkg_2
Generates the necessary files: CMakeLists.txt, package.xml, include/, and src/
Sets up a C++ ROS2 package ready for your node

Your structure should look like:

pkg_2/
├── CMakeLists.txt
├── include/pkg_2/
├── package.xml
└── src/

🧩 Step 2:

Writing the Node

Create a file:

cd pkg_2/src
nano my_node.cpp

This node doesn’t publish yet — but it’s alive and running, ready to communicate.
📄 Step 3:

Editing

CMakeLists.txt

This tells ROS2 how to compile your C++ node and link it with the rclcpp library
📦 Step 4:

Updating package.xml

Open:

nano ../package.xml

And add your dependency to xml file:

<depend>rclcpp</depend>

🏗️ Step 5:

Building the Package

Go back to your workspace:

cd ~/ros2_ws
colcon build
source install/setup.bash

colcon is the build tool front-end. It discovers packages in src/, figures out build order from package manifests, and runs the configured build tool (eg. ament_cmake) for each package. Results go into build/, install/, and log/.

Discovery

: colcon scans src/ for packages (reads package.xml).
▶️ Step 6:

Running the Node

Run it with:

ros2 run pkg_2 my_node

Output:

[INFO] [my_cpp_node]: Hello guys this is nagu !

🎉 Congratulations — you’ve just created your first C++ ROS2 node!

Typical errors you might encounter and what they mean

Package 'pkg_2' not found:
You didn’t source install/setup.bashof your workspace (or you built under a different overlay).

Linker errors (undefined references):
you forgot to ament_target_dependencies(... rclcpp)or find_package(rclcpp).

Runtime errors about DDS:
rclcpp::initcan fail if the rmw implementation is missing or environment variables are wrong. Also firewall settings can block DDS discovery.

It appears that the colcon command is not currently installed on your system. This tool is required to build ROS2 workspaces. You may install it using the following commands:

sudo apt update
sudo apt install python3-colcon-common-extensions -y

💬 What’s Next?

In my next blog, I’ll extend this node to publish messages at regular intervals and create a subscriber node to receive them — this is where true ROS2 communication begins.

Stay tuned 🚀
Until then, keep experimenting and exploring the power of ROS2!

🧩 Bonus Tip:

To see all running nodes:

ros2 node list

To check logs:

ros2 topic echo /rosout

🪶 >Written by NARASIMHA ALIAS Nagu
💡 "Don't prove, just improve."
follow me for more knowledge

humble turtlesim

naguballa77 — Mon, 27 Oct 2025 07:40:35 +0000

ros2 turtlesim

the humble turtlesim is a beginer level simulation tool

Hey everyone 👋 I’m Nagu, and this is my first blog post on the DEV Community!
In this post, we’ll explore Turtlesim, a fun and simple simulator in ROS 2 (Robot Operating System 2) — perfect for beginners who want to start learning robotics and ROS commands.

🚀 What is ROS 2 Humble?

ROS 2 Humble Hawksbill is a popular Long-Term Support (LTS) version of ROS 2.
It’s widely used for building and simulating robots — from simple mobile bots to advanced AI-driven systems.

🐢 What is Turtlesim?

Turtlesim is a lightweight simulator that shows a small turtle in a 2D world.
It’s often the first step to understanding ROS concepts such as:

Nodes 🧩 (independent programs)

Topics 🗣️ (communication channels)

Services ⚙️ (request/response system)

Parameters ⚡ (settings and configurations)

⚙️ Step 1: Install ROS 2 Humble

If you haven’t installed ROS 2 yet, open your terminal and run:

sudo apt update && sudo apt upgrade -y
sudo apt install ros-humble-desktop

Then source it:

source

/opt/ros/humble/setup.bash

(Tip: Add this line to your .bashrc so it auto-loads every time you open a terminal)

🧩 Step 2: Install Turtlesim

sudo apt install ros-humble-turtlesim

Check if it’s installed:

ros2 pkg list | grep turtlesim

note :sometimes ros2 command not found in terminal
in that case it better to switch to root terminal by the below command

sudo su

🖥️ Step 3: Run Turtlesim

Launch the turtlesim window:

ros2 run turtlesim turtlesim_node

A blue window will appear with a turtle in the center 🐢💙

🎮 Step 4: Control the Turtle

Open another terminal and run:

ros2 run turtlesim turtle_teleop_key

after clicks of some keys
⬆️➡️⬇️⬅️

Now use your arrow keys to move the turtle around.
Congrats — you just published your first commands in ROS 2!

🧠 Step 5: Explore Basic Commands

List all active topics:

ros2 topic list

See messages being published: while you are controling the turtle by arrow keys

ros2 topic echo /turtle1/cmd_vel

---
linear:
  x: 0.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: -2.0
---
linear:
  x: 0.0
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 2.0
---

WHEN YOU TOUCH THE EDGE OF THE WINDOW it publish to the

turtlesim_node
terminal
[WARN] [1761550426.649414936] [turtlesim]: Oh no! I hit the wall! (Clamping from [x=11.120421, y=4.634281])

Clear the screen:

ros2 service call /clear std_srvs/srv/Empty

Change the background color:

ros2 param set /turtlesim background_r 200
ros2 param set /turtlesim background_g 100
ros2 param set /turtlesim background_b 150
ros2 service call /clear std_srvs/srv/Empty

💡 What You Learned

✅ How to install and run ROS 2 Humble
✅ How to launch and control Turtlesim
✅ How to explore topics, services, and parameters
the official website for ros

This is just the beginning of your ROS 2 journey — next, we’ll write a Python node to move the turtle automatically!

✍️ Final Words

Thanks for reading!
If you enjoyed this post or found it helpful, leave a ❤️ and follow me for more tutorials on ROS 2, Ubuntu, and Ethical Hacking.
and since it is my first ever blog please support me for more info

“Don’t prove, just improve.” — Nagu

Would you like me to write your next post script — the one about controlling Turtlesim using Python code
see you soon guys