SCD40 NDIR CO2 Sensor Module (I2C) | ATMOSFÆR ENGINEERING

High-precision NDIR (Non-Dispersive Infrared) CO2 sensor with integrated temperature and humidity measurement. Provides true CO2 detection (not estimated) using photoacoustic sensing technology. Measures CO2 from 400-2000ppm with ±(40ppm + 5%) accuracy. Features I2C interface, automatic self-calibration, and ultra-low power consumption. Ideal for indoor air quality monitoring, HVAC control, smart homes, and environmental sensing applications.

Technical Specifications:

• Sensor IC: Sensirion SCD40 (NDIR CO2 sensor)
• Sensing Technology: Photoacoustic NDIR (true CO2 measurement)
• Interface: I2C (TWI)
• Operating Voltage: 2.4V - 5.5V (3.3V or 5V compatible)
• CO2 Measurement Range: 400 - 2000 ppm (optimized for indoor use)
• CO2 Accuracy: ±(40 ppm + 5% of reading)
• Temperature Range: -10°C to +60°C
• Temperature Accuracy: ±0.8°C
• Humidity Range: 0 - 100% RH
• Humidity Accuracy: ±6% RH
• Response Time: ~60 seconds (for 63% step change)
• Warm-up Time: <1 minute
• I2C Address: 0x62 (fixed)
• Update Interval: 5 seconds (default)
• Power Consumption: <18mA average, <50mA peak
• Operating Temperature: -10°C to +60°C
• Operating Humidity: 0 - 95% RH (non-condensing)
• Module Dimensions: ~10mm x 10mm x 7mm (sensor), breakout board varies

Pin Configuration:

• VCC/VDD: Power supply (2.4V - 5.5V)
• GND: Ground
• SDA: I2C data line
• SCL: I2C clock line

Features:

• True CO2 measurement using NDIR technology (not estimated like eCO2)
• Integrated temperature and humidity sensors (3-in-1)
• Photoacoustic sensing for compact size and low power
• Automatic self-calibration (ASC) over 7 days
• Factory pre-calibrated (ready to use)
• Low power consumption (<18mA average)
• Small footprint for compact designs
• I2C interface for easy integration
• On-chip signal processing
• Long-term stability (no drift)

Measured Parameters:

• CO2: 400-2000 ppm (actual measurement, not estimated)
• Temperature: -10°C to +60°C
• Humidity: 0-100% RH

Applications:

• Indoor air quality (IAQ) monitoring
• Smart home ventilation control
• HVAC and building automation
• Office and classroom CO2 monitoring
• Sleep quality and bedroom air monitoring
• Grow rooms and greenhouses
• Smart thermostats
• Air quality meters and displays
• IoT environmental sensors
• COVID-19 ventilation assessment

Automatic Self-Calibration (ASC):

• Sensor assumes exposure to fresh air (400ppm) regularly
• Automatically corrects baseline over 7 days
• Can be disabled for special applications
• Manual calibration also supported

Advantages over eCO2 Sensors (CCS811, ENS160):

• Real CO2 measurement vs calculated estimate
• Not fooled by VOCs, cleaning products, cooking
• Industry-standard NDIR technology
• Higher accuracy for actual CO2 levels
• Ideal for health/safety applications

Important Notes:

• Optimized for 400-2000ppm (typical indoor range)
• For outdoor use or high-CO2 environments, readings may be less accurate >2000ppm
• Allow 7 days for automatic self-calibration to stabilize
• Keep sensor away from direct airflow (fans, AC vents)
• Ensure regular exposure to fresh air for ASC to work properly

Typical CO2 Levels:

• 400-600 ppm: Outdoor/fresh air
• 600-1000 ppm: Good indoor air quality
• 1000-1500 ppm: Acceptable, ventilation recommended
• 1500-2000 ppm: Poor air quality, fatigue/drowsiness possible
• >2000 ppm: Inadequate ventilation, health concerns

Compatible with Arduino, ESP32, Raspberry Pi, STM32, and any microcontroller with I2C support. Libraries available for Arduino IDE (Sensirion I2C SCD4x) and Python.