George Smart - M1GEO

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An ESP8266 based Air Quality Sensor

Posted: 04 Feb 2021 09:45 AM PST
https://www.george-smart.co.uk/2021/...quality-sensor



Some time ago I had reason to log the quality of air in a room. We needed
to know what the levels of carbon monoxide and carbon dioxide were at a
given time. I quickly produced a thing on a strip of veroboard that would
use an ESP8266 to log over WiFi to the ThingSpeak platform. This proved to
be useful, and so I made a couple more on a PCB for various other locations.








The sensor uses a Â*CCS811 (a low-power digital gas sensor) , BME280 (sensor
measuring relative humidity, barometric pressure and ambient temperature)
and DHT22 (capacitive humidity sensing digital temperature and humidity)
sensors, with an OLED display and a small 5V 40mm fan to waft some air
around prior to taking a reading. In reality the project no longer needs
the DHT22 sensor, since the BME280 device provides better temperature and
humidity measurements and adds air pressure readings. But it is included
for historical reasons on my project. Feel free to omit it!








The project is very simple, as it just hooks up modules purchased from
eBay. The modules cost less than £2 each at the time of writing and came
from eBay or AliExpress.




Since this time, others have asked me for the design files, and so I have
now shared them on GitHub: github.com/m1geo/ESP8266-Air-Quality-Sensor. The
link contains everything you need to create your own! PCB files, source
code and schematic.




If you follow the GitHub link above, you fill find two folders. These are
explained in the subsequent sections below.



Code




The code folder contains the Arduino code which runs on the ESP8266 device.
Youll need to source libraries for the SSD1306 OLED, the DHT22 (or cheaper
DHT11), the Adafruit BME280 module, and the Adafruit CCS811 module. All
these are available inside the Arduino IDE.




The MCU board used is a ESP8266 NodeMCU 1.0. This, and all the modules are
easily sourced from the usual places (eBay, AliExpress, etc.), and are
cheap. Youll need to create a ThingSpeak account and then enter your API
Key and channel number into the source code, as well as your WiFi name and
passcode.



Board




TheÂ*boardÂ*folder contains an example schematic design and basic PCB gerber
files. You can use these gerber files to have a PCB made. All the cheap PCB
houses will produce this board fine. The board files supplied are for the
board shown above.



Files




All files are on GitHub: github.com/m1geo/ESP8266-Air-Quality-Sensor