M5Stack CO2 Unit – SCD40 Temperature & Humidity Sensor | U103

The M5Stack CO2 Unit uses the Sensirion SCD40 photoacoustic sensor to measure carbon dioxide together with temperature and relative humidity. It is designed for indoor air-quality dashboards, ventilation control prototypes, classrooms, offices, greenhouses, and environmental data logging. The unit communicates over I2C at address 0x62 and includes onboard power conversion for Grove integration. Reliable CO2 readings require appropriate warm-up, open airflow around the sensing area, separation from human breath and heat sources, and careful use of automatic self-calibration in environments that periodically return to fresh-air conditions.

Indoor Air-Quality Monitoring with the M5Stack CO2 Unit

Measure CO2 with the Sensirion SCD40

The SCD40 uses photoacoustic sensing to measure actual carbon dioxide concentration rather than estimating CO2 only from other gas signals. The documented measurement range is 400–2000 ppm.

Track Temperature and Relative Humidity

Integrated temperature and humidity outputs help characterize room conditions and support dashboards, comfort monitoring, and compensation workflows.

Connect through I2C Address 0x62

The Grove I2C interface lets a compatible host read all three environmental values from one module. The documented default address is 0x62.

M5Stack CO2 Unit Applications

• Indoor air-quality dashboards
• Demand-controlled ventilation prototypes
• Classroom, office, and meeting-room monitoring
• Greenhouse and plant-environment logging
• Smart-home environmental automation

How to Integrate the M5Stack CO2 Unit

1. Place the unit where room air can circulate freely and away from direct breath, windows, heaters, sunlight, and exhaust vents.
2. Connect it to a compatible Grove I2C port and confirm that address 0x62 is available.
3. Start periodic measurement and allow the sensor to stabilize before evaluating the result.
4. Log CO2, temperature, humidity, timestamp, and sensor status together.
5. Validate automatic self-calibration settings against the real ventilation pattern of the deployment environment.

M5Stack CO2 Unit Deployment Notes

• Direct human breath near the sensor can cause rapid temporary CO2 increases.
• Enclosures must provide airflow without exposing the sensor to condensation, dust, or liquid.
• Automatic self-calibration assumes the sensor periodically experiences a fresh-air reference level and may not suit continuously occupied or high-CO2 spaces.
• The onboard temperature value can be influenced by nearby electronics and enclosure heat.
• This development sensor is not a certified life-safety, fire, or confined-space gas detector.

M5Stack CO2 Unit Development Resources

• M5Stack CO2 Unit Official Documentation
• UiFlow2 Development Environment
• Arduino IDE