ROS2 LED Strip Controller

This project is a ROS2 LED Strip controller written in C++ using pigpio with button input for switching colors, running with pigpio on a Raspberry Pi Model 3B+.

Design

• The led_strip_output node defines a subscriber for "led_controller1/new_color", a std_msgs::msg::ColorRGBA object. Upon receipt of a new color by any publisher, the node will set the LED strip to that color.
• The button_pub node defines a publisher for "led_controller1/new_color" according to GPIO input from a pushbutton. Depending on which color is next in the queue, a button press will immediately publish a new color. The color rotation goes as follows: White → Red → Blue → Purple → Medium Slate Blue → Off → White. New colors can be added in the button_pub.cpp file in the node's constructor.

Equipment

• 24V LED strip and power supply with RGB input
• 3 logic-level mosfets for LED strip control
• Raspberry Pi 3B+ running Ubuntu Server 20.04 (Ubuntu is recommended for ROS2 installation)
• Pushbutton

Hardware Setup

pigpio uses Broadcom numbers for addressing the Raspberry Pi's GPIO outputs. The GPIO arrangement diagram for each Raspberry Pi distribution is available here. The following GPIO constants can be changed in their corresponding header files.

• LED Strip:
  • Red: GPIO 2
  • Green: GPIO 3
  • Blue: GPIO 4
• Pushbutton: GPIO 17

Requirements

• ROS2 Galactic
• pigpio

Installation and How To Run

1. Make sure ROS2 Galactic and pigpio are installed onto your Raspberry Pi. pigpio-master should be in your home/user directory (~/), as the CMakeLists.txt configuration searches for it there.
2. Clone this repository and after sourcing your ROS2 installation (source /opt/ros/galactic/setup.bash), run colcon build in the ROS2CPP/led_strip_controller repository folder.
3. Open a new terminal.
4. Enter your root shell using sudo -i. This is required for pigpio GPIO setting.
5. Navigate to the repository directory in the new shell.
6. In a new terminal, install the newly built package using . install/setup.bash from within the ROS2CPP/led_strip_controller repository folder.
7. Before running the program, kill all currently running pigpio processes: killall pigpiod
8. Run the program with ros2 launch led_strip_controller led_launch.py.

Running on Raspberry Pi Startup (Ubuntu 20.04 Systemd)

1. In both startup_script.sh, and controller_startup.service, change the references to this repository's files to match where you downloaded this repository.
2. Give the system permissions to run startup_script.sh: sudo chmod 775 [your_path]/ros2-pi-leds/startup_script.sh
3. Copy controller_startup.service to /etc/systemd/system/ (e.g: sudo cp controller_startup.service /etc/systemd/system/).
4. Enable the service from the terminal with sudo systemctl enable controller_startup.service. To start the service at the same time, run sudo systemctl --now enable controller_startup.service