This repository contains NodeMCU Lua source code for a mobile CO₂ monitor. I found it quite interesting to see how bad the air inside meeting rooms and train carriages can get, and how well ventilation in other areas can work. There is also OpenSCAD source code for 3D-printing a case – however, as I relied on hand-soldering rather than designing a PCB for this task, it will likely need adjustments.
- Display for CO₂, temperature, humidity, and battery level
- Logging to InfluxDB
- WiFi roaming (i.e., can connect to more than one WiFi network)
- Processor: ESP8266
- CO₂ sensor: SCD4x (In principle, adding support for MH-Z19 and similar is not hard, however those rely on a 5V supply which this board does not provide)
- Display: 128x64 OLED via SSD1306 (128x32 also supported with some changes)
- Power Supply: AliExpress TP4056 charge controller + BMS board; 2.5V cutoff
- Battery: Regular 18650 LiIon cell; LiPo also works
WiFi and InfluxDB configuration is read from src/config.lua.
You will need the following entries.
The application takes a list of WiFi networks and tries to connect to them in order, waiting a few minutes between connection attempts. Configure them like so:
station_cfgs[1] = {ssid = "home network", pwd = "swordfish"}
station_cfgs[2] = {ssid = "37C3-open" }These settings are optional. Specify a URL and attributes in order to enable
InfluxDB publishing. For instance, if measurements should be stored as
mh_z19,location=lounge in the sensors database on
http://influxdb.example.org, the configuration is as follows.
influx_url = 'http://influxdb.example.org/write?db=sensors'
influx_attr = ',location=lounge'You can also use the esp8266_XXXXXX device id here, like so:
influx_url = 'http://influxdb.example.org/write?db=sensors'
influx_attr = ',location=' .. device_idOptionally, you can set influx_header to an HTTP header that is passed as
part of the POST request to InfluxDB.
Mirrors of this repository are maintained at the following locations: