Sensor Logging

This app was created for logging and visualizing temperature and humidity data using a Raspberry Pi and a DHT22 module. It also features an optional IFTTT notification for high temperature alerts, which can be defined in the script config.

Hardware Requirements

• Raspberry Pi (3B or better recommended)
• DHT22 Module

Software Requirements

• Node (Installed via nvm)
• Python3

Setup

This guide assumes you're already familiar with installing Raspberry Pi OS (formly known as Raspbian) and have already installed Node via nvm. Setting up the project is fairly straight forward:

1. Setup python script
2. Build web server
3. Create systemd service

1. Setup python script

Please note: This script requires the Adafruit_DHT library. Please note this library has been deprecated, so use with caution. To get started open a new terminal and run:

sudo pip3 install Adafruit_DHT

Next you'll need to create a config.ini. To use the provided example open a terminal, navigate to the repo directory, and run the following command:

cp config-sample.ini config.ini

Once created, open the config and confirm that DHT_PIN is set to the correct GPIO number on your Raspberry Pi (not the pin number itself). For example I use GPIO #14, but on the Raspberry Pi it's pin #7.

The last step is to create a cron job. In a terminal run crontab -e, and append the following line at the bottom:

* * * * * python3 sensors/sensors.py

Data will be logged to ./data every minute in CSV format.

IFTTT (optional)

To enable IFTTT webhook notifications, open your config and under the [ifttt] section set ENABLED to 1 or TRUE, provide your KEY and EVENT name, and set WARNING_TEMP to the desired value.

2. Build web server

Once you've completed script setup the next step is to install the web server dependencies and build the frontend application. In terminal navigate to ./server and run npm i to install the server dependencies.

Navigate to the ./server/client directory and run the npm i command again to install the frontend client dependencies.

Lastly, while still in the ./server/client directory run npm run build to build the frontend client app.

3. Create systemd service

Open rpisensors.service and make sure that the ExecStart and User options are correct.

Copy rpisensors.service to /etc/systemd/system/rpisensors.service by opening a terminal, navigating to the project root directory, and running:

sudo cp rpisensors.service /etc/systemd/system/rpisensors.service

Since nvm will manage our node/npm versions a simple shell script is used to properly create the service, which can be found in start.sh. This script must be executable by running chmod +x /path/to/script/start.sh

All that's left is enabling and starting our new service with the following commands:

systemctl enable rpisensors
systemctl start rpisensors

To check that the service started properly run systemctl status rpisensors.

And that's it! You can now view the frontend by navigating to your rPi's IP address on port 5000 (or whichever port is defined in your PORT environment variable).

Special thanks to joepie91 for their guide on running a Node.js application using nvm as a systemd service!