ClearAir

Kira Tully (ephemeral.cx)

A minimalist, DIY PurpleAir clone.

Note: This project may go long periods of time without being updated, however it is actively used and maintained. Bug reports and pull requests are welcome.

About

ClearAir is DIY PurpleAir clone built to be a minimalist replacement. It uses the same sensors and calculations, but for a third of the cost. A Ruby script is provided for reading the current values from the sensor over the network. Other frontends/clients can be written tailored to your needs.

Hardware

ClearAir was built and tested on an Adafruit Feather M0 WiFi.

• Adafruit Feather M0 WiFi
• Adafruit BME688
• Adafruit PMSA003I
• 5V 1A (1000mA) USB port power supply
• A micro-usb cable

Usage

Setting up the hardware

BME688	PMSA003I
3V -> 3V	3V -> 3V
GND -> GND	GND -> GND
SCL -> SCK	SCL -> SCL
SDA -> SDI	SDA -> SDA

A Fritzing file is located at docs/ClearAir.fzz.

Wiring diagram:

Compiling & Uploading

These instructions are for Linux.

1. Run scripts/download_dependencies.sh to download tooling dependencies.
2. Create src/secrets.h with the following content:

   #define _SSID "your_ssid"
   #define _PASSPHRASE "passphrase"
   

3. Edit src/main.h with appropriate IP & network settings
4. Then:

   $ make
   $ make upload
   

Reading Air Quality

To read values from the device, run ./client.rb [HOST]. Ruby is needed to run this script.

From here other frontends/clients can be written tailored for your needs. Reading from the sensor is as simple as opening a TCP socket and reading the JSON value that is returned.

An example response is as such:

{
  "air_quality_index": 9,
  "air_quality_category": "Good",
  "pm25": 2.00,
  "temperature": 23.07,
  "humidity": 53.14,
  "pressure": 1001.74
}

Networking

The default port is 2424. Don't forget to add rules to allow communication on this port on any firewalls or gateways between the client and the server.

License

GPLv3