ROS2 Python package to controll a 'Light Beacon'

Toggle light mode, by sending servo/PWM(RC) from the RPi GPIO-pins to the LED-Light Beacon.

This is the first "smoking/burning" release...

flowchart LR
    A(Power Up)-->|On| B(1.Rotating Fast)
    R(6.Reset)   -->|Off/On|B(1.Rotating Fast)
    B --> |cycle pwm|C(2.Rotating Slow)
    C --> |cycle pwm|D(3.Flashing)
    D --> |cycle pwm|E(4.Strobing)
    E --> |cycle pwm|F(5.LED Off)
    F --> |cycle pwm|B

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ROS2 Package/Module Behaviour

1. Once: Power up + Toggle LightBeacon-mode to LEDoff
2. Once: Read/Set ROS2 Parameters for the module
3. Repeatedly: Subscripe on topic
4. Repeatedly: Send needed number of PWM-cycles to toggle the Light Beacon to the requested Light-mode.

graph TD
    S(Start) --> A
    A(Read Parameters) -->|default values| B
    B(far:fa-lightbulb Power up beacon) --> C
    C(Wait for & Interpret Input) --> |No. cycles| D
    D(Perform PWM-cycles) --> C
    E(ROS2 topic input) --> C

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Prerequisite: Software

• Ubuntu 20.04 (64bit) or newer
• Robot Operating System 2, ROS2 (Version Galathic)

  ...do the ROS2-installation stuff...

Prerequisite: Linux/Ubuntu vs. Software

Ubuntu Shell

 $ sudo apt install python3-pip
 $ sudo apt-get install python3-rpi.gpio
 $ sudo pip3 install gpiozero

Prerequisite: Hardware

• Single Board Computer(SBC): Raspberry Pi 3/4
• Light Beacon - 3-wire (Same kind of connector/signal that trad. RC-servo uses)

🌐Google tips to find/order light beacon from eBay/AliExpress/Wish/Amazon/...
1) "Remote control RC Car LED Rotating Beacon Light Flashing"
2) "RC DIY LED Rotating Beacon Light Flashing for 1:14"

.

Dowload and install this ROS2 packages

Create a ROS2 workspace (in my exampel '~/ws_ros2/')
Dowload ROS2 package by using 'git clone'

🤔There is probably better tutorials how to do this...
...but here is how I made it.

Ubuntu Shell

~$ mkdir -p ~/ws_ros2/src
~$ cd ~/ws_ros2/src
~/ws_ros2/src$ git clone https://github.com/Pet-Series/pet_ros2_lightbeacon_pkg.git
~/ws_ros2/src$ cd ..
~/ws_ros2$ colcon build --symlink-install
~/ws_ros2$ source /opt/ros/galactic/setup.bash
~/ws_ros2$ source ./install/setup.bash

ROS2 Launch sequence

Ubuntu Shell

 $ ros2 run pet_ros2_lightbeacon_pkg pet_lightbeacon_node
  [INFO] [1646246566.984787281] [light_beacon_node]: light_beacon_node initiating
  [INFO] [1646246566.997037838] [light_beacon_node]: light_beacon_node has started
  [INFO] [1646246567.000520111] [light_beacon_node]: - beacon_power  GPIO-pin: 23
  [INFO] [1646246567.003899033] [light_beacon_node]: - beacon_signal GPIO-pin: 24
  [INFO] [1646246567.007907337] [light_beacon_node]: - beacon_mode  ROS Topic: beacon_mode

ROS2 Topics used by this package

Manuover the light beacon from the command line by enter one of the following commands. Ubuntu Shell

$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: RotatingFast" -1
$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: RotatingSlow" -1
$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: Flashing" -1
$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: Strobing" -1
$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: LEDoff" -1
$  ros2 topic pub /beacon_mode std_msgs/msg/String "data: Reset" -1

ROS2 Parameters used by this package

Save a "dump" of all the parameters that light_beacon_node uses. Ubuntu Shell

$ ros2 param dump /light_beacon_node --print
  /light_beacon_node:
    ros__parameters:
      beacon_topic: beacon_mode
      gpio_pin_power: 23
      gpio_pin_signal: 24
$ 

$ ros2 param describe /light_beacon_node beacon_topic 
  Parameter name: beacon_topic
    Type: string
    Description: GPIO-pin for input/signal to toggle state [default <24>]
    Constraints:
$ 

$ ros2 param describe /light_beacon_node gpio_pin_signal 
Parameter name: gpio_pin_signal
  Type: integer
  Description: GPIO-pin for input/signal to toggle state [default <24>]
  Constraints:
$ 

$ ros2 param describe /light_beacon_node gpio_pin_power 
  Parameter name: gpio_pin_power
    Type: integer
    Description: GPIO-pin for ligh_beacon +3.3V-power [default <23>]
    Constraints:
$