jsspric / aws-deepracer-i2c-pkg

The DeepRacer I2C ROS package creates the battery_node that is responsible for providing the vehicle battery level information.

DeepRacer I2C Package

Overview

The DeepRacer I2C ROS package creates the battery_node which is part of the core AWS DeepRacer application and will be launched from the deepracer_launcher. More details about the application and the components can be found here.

This node is responsible for providing the vehicle battery level information. It provides functions to read the battery level values from the I2C bus and return the corresponding level information.

License

The source code is released under Apache 2.0 (https://aws.amazon.com/apache-2-0/).

Installation

Prerequisites

The DeepRacer device comes with all the pre-requisite packages and libraries installed to run the i2c_pkg. More details about pre installed set of packages and libraries on the DeepRacer, and installing required build systems can be found in the Getting Started section of the AWS DeepRacer Opensource page.

The i2c_pkg specifically depends on the following ROS2 packages as build and execute dependencies:

• deepracer_interfaces_pkg - This packages contains the custom message and service type definitions used across the AWS DeepRacer core application.

Downloading and Building

Open up a terminal on the DeepRacer device and run the following commands as root user.

1. Switch to root user before you source the ROS2 installation:

    sudo su
   

2. Source the ROS2 Foxy setup bash script:

    source /opt/ros/foxy/setup.bash 
   

3. Create a workspace directory for the package:

    mkdir -p ~/deepracer_ws
    cd ~/deepracer_ws
   

4. Clone the i2c_pkg on the DeepRacer device:

    git clone https://github.com/aws-deepracer/aws-deepracer-i2c-pkg.git
   

5. Fetch unreleased dependencies:

    cd ~/deepracer_ws/aws-deepracer-i2c-pkg
    rosws update
   

6. Resolve the i2c_pkg dependencies:

    cd ~/deepracer_ws/aws-deepracer-i2c-pkg && rosdep install -i --from-path . --rosdistro foxy -y
   

7. Build the i2c_pkg and deepracer_interfaces_pkg:

    cd ~/deepracer_ws/aws-deepracer-i2c-pkg && colcon build --packages-select i2c_pkg deepracer_interfaces_pkg
   

Usage

Although the battery_node is built to work with the AWS DeepRacer application, it can be run independently for development/testing/debugging purposes.

Run the node

To launch the built battery_node as root user on the DeepRacer device open up another terminal on the DeepRacer device and run the following commands as root user:

1. Switch to root user before you source the ROS2 installation:

    sudo su
   

2. Source the ROS2 Foxy setup bash script:

    source /opt/ros/foxy/setup.bash 
   

3. Source the setup script for the installed packages:

    source ~/deepracer_ws/aws-deepracer-i2c-pkg/install/setup.bash
   

4. Launch the battery_node using the launch script:

    ros2 launch i2c_pkg i2c_pkg_launch.py
   

Launch Files

The i2c_pkg_launch.py is also included in this package that gives an example of how to launch the deepracer_navigation_node.

from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        Node(
            package='i2c_pkg',
            namespace='i2c_pkg',
            executable='battery_node',
            name='battery_node'
        )
    ])

Node Details

battery_node

Services

Service Name	Service Type	Description
battery_level	BatteryLevelSrv	A service that is called to get the current vehicle battery level information in the range of [0 to 11].

Resources

• AWS DeepRacer Opensource getting started: https://github.com/aws-deepracer/aws-deepracer-launcher/blob/main/getting-started.md