Disclaimer and credits: this repository is a fork from https://github.com/kmetz/coro2sens.
Several changes have been made in this fork. Please also consult the README file of the original version.
The following sections have been updated for this repository:
Build a simple device that warns if CO₂ concentration in a room becomes a risk for COVID-19 aerosol infections.
- Measures CO₂ concentration in room air.
- Controls two LEDs (green + orange/red) for indication of warning/critical CO2 level.
- Controls a NeoPixel ring for indication of CO2 level and its criticality (optional).
- A buzzer can be connected that alarms if levels are critical (optional).
- Also opens a WiFi portal which shows current readings and a graph (not connected to the internet; optional).
- Can be built for ~ $60 / 50€ (parts cost).
This project was heavily inspired by ideas from Umwelt-Campus Birkenfeld.
You can also find a good overview of the topic by Rainer Winkler here: Recommendations for use of CO2 sensors to control room air quality during the COVID-19 pandemic.
The sensor used here is the Sensirion SCD30 (around 70 USD / 60 €).
The pressure compensation by an additional sensor BME280 is currently no longer supported in this forked repo.
| LED color | CO₂ concentration |
|---|---|
| Green ("all good") | < 800 ppm |
| Yellow ("open windows") | 800 – 1000 ppm |
| Red ("leave room") | > 1000 ppm |
Based on a Recommendation from the REHVA (Federation of European Heating, Ventilation and Air Conditioning associations, rehva.eu) for preventing COVID-19 aerosol spread, especially in schools.
You can read current levels and a simple graph for the last hour by connecting to the WiFi coro2sens_<serialno> that is created.
Most devices will open a captive portal, immediately showing the data. You can also open http://10.0.0.1/ in a browser.
You can also control most of the settings via the web interface. Visit http://10.0.0.1/config in a browser.
- A NodeMCU board (any other ESP8266 based board might also work).
- Sensirion SCD30 I2C carbon dioxide sensor module (mouser, digikey).
- (optional) NeoPixel ring
- (optional) 2 LEDs (green + yellow/red); the green one indicates "all good" (< 800 ppm) the other one that this limit has been exceeded
- (optional) A 3V piezo buzzer or a small speaker.
- (optional) You may want to work with Guido Burger's IoT Octopus PCB. This helps fixing the sensor and the NodeMCU, as well as the LEDs.
- (optional) A nice case :) Make sure the sensor has enough air flow.
- An Arduino IDE (select the board "NodeMCU 1.0 (ESP-12E Module)", v2.7.1 and v2.7.4 have been tested and should work; you may need to install the board support for the "esp8266")
- Arduino libraries:
- FastLED (via the library manager)
- zip file libraries (download .zip file, then import it via Sketch –> Include Library –> Add .ZIP Library...)
| ESP8266 pin | goes to |
|---|---|
| 3V3 | SCD30 VIN |
| GND | SCD30 GND, Buzzer (-) |
| SCL / D1 | SCD30 SCL |
| SDA / D2 | SCD30 SDA |
| D3 | LED DIN |
| D5 | Green LED |
| D6 | Buzzer (+) |
| D7 | Warning LED (yellow or red is a good idea) |
| D8 | NeoPixel ring |