The UNIT CO2 from M5Stack is a photoacoustic Carbon Dioxide (CO2) Unit that will tell you the CO2 PPM (parts-per-million) composition of ambient air.

The unit has a built-in Sensirion SCD40 sensor powered by buck converter circuitry and communication handled via I2C. It has a range of 400~2000 ppm with an accuracy of ±(50 ppm + 5% of reading).

It supports temperature and humidity measurements too - perfect for environmental sensing, scientific experiments, air quality and ventilation studies, and more.

Features

• CO2 concentration detection
• Temperature and humidity measurement
• I2C communication (Add: 0x62)
• Integrated 5V -> 3.3V Buck converter
• 2x Brick holes
• HY2.0 4-pin interface

Specifications

Resources	Parameter
CO2 Measurement range	400 ~ 2000 ppm
CO2 Sampling accuracy	±(50 ppm + 5% of reading)
Temperature range	-10 - 60 °C
Humidity range	0 - 95 %RH
Communication protocol	I2C: 0x62
Net weight	7.54g
Gross weight	13.13g
Product dimensions	48mm x 24mm x 16mm
Package size	134mm x 61mm x 16.3mm
Housing material	Plastic ( PC )

Resources

• Product Documentation
• Schematic
• SCD40 datasheet
• SY8089AAAC datasheet
• Arduino Examples
  • M5Unit-CO2 with M5Core
  • M5Unit-CO2 with M5Atom
  • M5Unit-CO2 with M5StickC
  • M5Unit-CO2 with M5StickCPlus

Pinout

CO2 Unit	SCL	SDA	5V	GND
M5Core (PORT A)	GPIO22	GPIO21	5V	GND
M5Core2 (PORT A)	GPIO22	GPIO21	5V	GND
M5Atom (PORT A)	GPIO32	GPIO26	5V	GND
M5StickC/Plus (PORT A)	GPIO33	GPIO32	5V	GND
M5Station (PORT A1,A2)	GPIO33	GPIO32	5V	GND