edorosh / co2-indoor-monitor

CO2 Indoor Monitor based on Arduino and MH-Z19B

CO2 Indoor Monitor (MH-Z19B)

A CO2 Monitor is a device that helps you understand the environmental Carbon Dioxide (CO2) levels in an office, room and other indoor area.

It first warns and then alarms in case of CO2 level reaches a nonacceptable level. It has 4 Digit 7-Segment Display Module, a LED illumination along with a Buzzer. Currently the device is powered by a USB source only.

CO2 Levels are measured as PPM (Parts Per Million). The standard outdoor level is around 350ppm, and is the optimum level for freshness. However, it can get up to 600ppm indoor without any adverse affects. Once it gets past 600ppm people will start noticing adverse affects.

The LED is GREEN when CO2 < 700ppm. It switches to BLUE when the level is < 1200ppm and finally it changes to red for the higher levels and starts playing back a song.

Circuit Schematic

Upload Firmware

New to Arduino? Check this official HOWTO. Before uploading the sketch check if you have all requried libraries insalled. You may want to copy all of them inside libraries manually into %Home%/Arduino/libraries or install them all via "Manage Libraries" option.

Project Structure

Folder	Description
firmware	Arduino Firmware
libraries	All required libraries
3d	STL and Step files for the enclosure
resources	Resources for the README file

List of used libraries

• GyverButton
• GyverTimer
• MH-Z19
• TM1637
• Non Blocking rtttl

Bill of Materials

• PCB Prototype Board 3x7cm
• Arduino Nano
• MH-Z19B
• Female PCB pins
• Passive Buzzer 5v (12mm)
• 2-way switch
• Connection wires
• RGB LED with common Cathode
• 4 digit 7 Segment Display TM1637
• 220 Ohm Resistor x2
• Hex Spacer 2M 6mm x2 with screws x2

3D Model

STL files for the enclosue are inside 3d folder. Here you may find Fusion 360 sources. I printed the parts with PETG material, 30% infill and 0.2mm layer height. PLA works worse and it easily breaks. The LED part is filled up by a Hot Glue. The Display is fixed by a Hot Glue as well. THe PCB board is fixed by 2 Hex Spacers.

License

MIT License. Not for a commercial usage.

TODO

• think about using platform.io
• add settings description
• add feature: blikning red
• add feature: different PWN values per colour
• add feature: repeating the melody
• add feature: add battery support