AirNode is an air quality monitoring device
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It measures:
- Temperature, highly accurate (0.1C)
- Humidity
- Volatile Organic Compounds (VOCs)
- Carbon Dioxide (CO2)
- Dust (PM 2.5, PM 10)
- Ambient Light
- 2 auxiliary gas sensors (MQ-package)
At the heart of it is an ESP8266 which sends the data over MQTT.
Why?
Mostly our of interest, and also to see whether I could tell when the indoor air becomes “unhealthy” or otherwise requires ventilation. Long-term I want to build this into my home automation system to automatically open windows / run fans / etc.
It’s pretty cool what you can measure with these sensors…
- Example of me cooking food (dust levels should rise and then slowly fall)
- Example of the trash getting stale (VOC climing up over days, then falling when trash is taken out)
- Example of the house being occupied (CO2 climing up when I get home)
Data
Put graphs of the data that it can capture here…
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Design
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Choosing Sensors
There’s quite a few options on the market
- Explain choice of CO2 sensor
- Explain choice of various temp/humidity sensors, and their accuracy, etc.
- Explain why I’m not measuring Oxygen, Ozone (expensive, inaccurate)
- Explain choice of PM dust sensor
Microcontroller
Since it has rather limited GPIO capabilities, it was a bit of a challenge to get everything connected. The trick is that everything communicates over I2C and UART.
Prototype
- Photo of prototype mess, if I have one
PCB Revisions
This took me many revisions to get right:
Revision 1-3
- Rev1
- Rev2
- Rev3 (missing)
Revision 4
Protip: Always print your PCB on paper first to verify the footprints!
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