Higher concentrations of CO2 inside will make you sleepy and have an impact on your wellbeing. During the current pandemic higher CO2 concentrations inside are also a pretty good indication for higher levels of aerosol and as such a higher risk for infection. The 'CO2 Ampel' (CO2 traffic light) will give you a visual representation of the current situation and remind you to open windows to keep you happy and healthy.
You can always get help by contacting us. The fastet way is probably our maxtrix chat channel, but you can always use our mailing list or any other contact methods found at https://www.un-hack-bar.de/kontakt/.
Have a list of all the parts necessary. We added an aliexpress link for convenience, but feel free to use other sources. The prices will vary among shops and we don't update the links.
|ESP32 development board||ESP-32 30Pin||Aliexpress Link|
|Infrared CO2 Sensor||mhz-19||Aliexpress Link|
|Active piezzo buzzer (optional)||KY-012||Aliexpress Link|
|LED-Ring (8 or 9 Pixel)||WS2812||Aliexpress Link|
|3m USB cable||USB cable||Aliexpress Link|
|red, green, black and white wires||Signal wires||no link|
|30 cm of shrinking tube||shrinking tube||no link|
| part | description | | 3mm pylwood | Any 3mm thick material will do. We use pine. You could even use acrylic. | | Wood glue | Glue for the case. | | Translucent filament | We used translucent PLA, but any filament will be OK. | | 3x10mm machine screws | Should be a cylinderhead screw. Sinkhead screws will probable need 3x12mm. | | Hot glue | To fix the electronics on the board. |
Solder the wires according to the connection schema:
There is also a PCB-version of this project available (to be documented).
pip3 install esphome
esphome co2sensor.yaml run
there is a quick setup on here your sensor should apper in the list on the left as soon it is connected via wifi.
|GND||KY-012 (GND)||passive buzzer will do as well|
|RX2 / D16||mhz-19 (TX)|
|TX2 / D17||mhz-19 (RX)|
|I2C SDA / D21||SSD1306 (SDA)|
|I2C SCL / D22||SSD1306 (SCL)|
If your ws2812 don't work on 3.3V power (most will do) you can try to use 5V instead. There are plenty different ws2812 builds so ymmv... if the leds don't work with 5V try to add a pullup resistor to your data line and a diode towards D4 to raise your high level while protecting your GPIO (https://forum.arduino.cc/index.php?topic=578735.msg3941756#msg3941756) looks like this:
either way it might be a good idea to have a capacitor between VCC and GND. my prototype worked without any of these, but from time to time some LEDs just randomly turn on and the lights flicker slightly when the sensor takes a measurement.
|400 ppm||none||no||more or less the baseline of the sensor hardware and means 'outside air quality'|
|400-800ppm||none||no||safe zone and can be considered good air quality|
|800-1000ppm||yellow||no||warning zone (consider to open windows) and is between medium and bad air quality|
|> 1000ppm||red + blink||no||hygienic bad air quality, chance for infections rise|