MOTH.CO2.2
This projects provides instructions for building a CO₂ sensor from commercially available electronic parts combined with 3D printed housing parts.
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The device uses the Sensirion SCD-41 Sensor, a small and high performance photoacoustic CO₂ sensor.
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The sensor measures CO₂, temperature, humidity and pressure. Measurements are rendered to the device display, and can also be shown in a simple chart to perceive recent measurement history. The display can be switched to an inverted dark mode. Thresholds are configurable, just like temperature display unit and timezone. An internal buzzer can be turned on to give acoustic feedback when CO₂ thresholds are exceeded.
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Measurements are stored on an internal SD-Card, thus effectively providing unlimited measurement history.
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WiFi connectivity can be used to access current and historic measurements and to change device configuration or to calibrate. Measurements can also be be auto published over the MQTT protocol.
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When operated in low power mode (no WiFi, 3 minute display update), the device lasts around 1 week on a single battery charge.
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The housing can be wall mounted, with or without theft protection.
The root folder of the project is structured as follows:
The Arduino Sketch running on the device, configuration files and some GFX Fonts used:
MOTH Core
Building instructions, drawings and printable files for the device:
MOTH Parts and Assembly
A react administration UI for the device:
MOTH Client
Data
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On display
The device display supports two display modes, "table" and "chart". In table mode the latest CO₂, temperature and humidity values are shown numerically
TODO :: image here
In chart mode one of CO₂, temperature, humidity or pressure are shown in a simple chart.
TODO :: image here
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Over Wifi
The device hosts a small react-web-application.
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client.html
This page resembles the device's tabular view of the latest measurement.
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chart.html
This page gives access to the full history of measurements. Given the size of the SD-Card, there will be no limit regarding storage, effectively the device will keep an indefinite list of measurements.
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server.html
This page gives access to the device's api. View status, configuration, data, upload file, calibrate, reset, ...
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MQTT
TODO :: describe
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TODO :: here or somewhere (!) have a set of basic introductions
License
Please be aware that all software in this project is licensed under the MIT license, while the drawings and 3d-printed parts are licensed under the Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license.