odroid-power-mate/example/logger

Odroid PowerMate Logger and Plotter

This directory contains two Python scripts to log power data from an Odroid PowerMate device and visualize it.

1. logger.py: Connects to the device's web server, authenticates, and logs real-time power data from its WebSocket to a CSV file.
2. csv_2_plot.py: Reads the generated CSV file and creates a plot image of the power, voltage, and current data over time.

Prerequisites

1. Clone this example

git clone https://github.com/hardkernel/odroid-powermate.git
cd odroid-powermate/example/logger

2. Python and Virtual Environment

It is highly recommended to use a Python virtual environment to manage project dependencies and avoid conflicts with other projects.

Ensure you have Python 3 installed.

1. Create a virtual environment: Open your terminal in this directory and run:

   python3 -m venv venv
   

   This will create a venv directory containing the Python interpreter and libraries.

2. Activate the virtual environment:

   • On Windows:

     .\venv\Scripts\activate
     

   • On macOS and Linux:

     source venv/bin/activate
     

   Your terminal prompt should now show (venv) at the beginning, indicating that the virtual environment is active.

3. Install Required Libraries

With the virtual environment activated, install the necessary Python packages:

pip3 install requests websockets protobuf pandas matplotlib python-dateutil

4. Protobuf Generated File

The logger.py script uses Google Protocol Buffers (Protobuf) to decode real-time data from the WebSocket. This requires a Python file, status_pb2.py, which is generated from a Protobuf definition file (status.proto).

How to Generate status_pb2.py:

1. Install Protobuf Compiler Tools: You need the grpcio-tools package, which includes the protoc compiler and Python plugins. You can install it via pip:

   pip3 install grpcio-tools
   

2. Locate the .proto file: Ensure you have the status.proto file in the current directory. This file defines the structure of the data messages.

3. Run the Compiler: Execute the following command in your terminal. This command tells protoc to look for status.proto in the directory (-I../../proto) and generate the Python output file (--python_out=.) in the same place.

   python3 -m grpc_tools.protoc -I../../proto --python_out=. status.proto
   

After running this command, the status_pb2.py file will be created, and logger.py will be able to use it.

Usage

The process is a two-step workflow: first log the data, then plot it.

Step 1: Log Power Data with logger.py

Run logger.py to connect to your Odroid Smart Power device and save the data to a CSV file.

Syntax:

python3 logger.py <host> -u <username> -p <password> -o <output_file.csv>

Arguments:

• host: The IP address or hostname of the Odroid Smart Power device (e.g., 192.168.1.50).
• -u, --username: The username for logging in.
• -p, --password: The password for logging in.
• -o, --output: The path to save the output CSV file. This is required if you want to generate a plot.

Example:

This command will log in and save the power data to power_log.csv.

python3 logger.py 192.168.1.50 -u admin -p mypassword -o power_log.csv

The script will continue to log data until you stop it with Ctrl+C.

Step 2: Generate a Plot with csv_2_plot.py

Once you have a CSV log file, you can use csv_2_plot.py to create a visual graph. You can also use the csv file recorded from PowerMate Web.

Syntax:

python3 csv_2_plot.py <input.csv> <output.png> [options]

Arguments:

• input_csv: The path to the CSV file generated by logger.py.
• output_image: The path to save the output plot image (e.g., plot.png).

Optional Arguments:

• -t, --type: Specify which plots to generate. Choices are power, voltage, current. Default is all three.
• -s, --source: Specify which power sources to include. Choices are vin, main, usb. Default is all three.

Example 1: Default Plot

This command reads power_log.csv and generates a plot containing power, voltage, and current for all sources, saving it as power_graph.png.

python3 csv_2_plot.py power_log.csv power_graph.png

Example 2: Custom Plot

This command generates a plot showing only the power and current for the MAIN and USB sources.

# main, usb power consumption
python csv_2_plot.py power_log.csv custom_plot.png --type power --source main usb

Example Output

Running the plot script will generate an image file similar to this:

The 5-unit scale is highlighted with a blue dotted line, and the 10-unit scale is highlighted with a red dotted line.