Adafruit SCD-40 - True CO2, Temperature and Humidity Sensor - STEMMA QT / Qwiic

Description:

The SCD-40 is a photoacoustic 'true' CO2 sensor that will tell you the CO2 PPM (parts-per-million) composition of ambient air. Unlike the SGP30, this sensor isn't approximating it from VOC gas concentration - it really is measuring the CO2 concentration! That means it's bigger and more expensive, but it is the real thing. Perfect for environmental sensing, scientific experiments, air quality and ventilation studies, and more.

Compared to the illustrious SCD-30, this sensor uses a different measurement technique, which allows it to be much smaller. The overall data quality should be very similar, however. Like the SCD-30, this sensor has data read over I2C, so it works very nicely with just about any microcontroller or microcomputer. There's both Arduino and Python/CircuitPython code so you can get started in a jiffy.

There are two variants of this sensor - the SCD-40 and SCD-41

• The SCD-40 is lower cost, and is perfect for indoor/outdoor air quality and CO2 measurements. It has a range of 400~2000 ppm with an accuracy of ±(50 ppm + 5% of reading)
• The SCD-41 is more expensive, and while it can definitely be used for air quality, it's wide range means its best used for industrial or scientific CO2 measurements where the ppm can get very high. It has a range of 400~5000 ppm with an accuracy of ±(40 ppm + 5% of reading)

This sensor can run from 3.3 to 5V but it's more important for it to have a quiet power supply with low ripple, than any particular voltage. For that reason we've added a 3.3V regulator and level shifters: when connecting to a 5V microcontroller like an Arduino UNO the 5V supply is often shared with other electronic components that add noise. The onboard regulator will keep the voltage nice and quiet. For advanced hackers, they can cut/solder the back traces to change whether the regulator is enabled and what I2C logic level is desired.

Specifications:

• Photoacoustic CO2 sensor technology
• Integrated temperature and humidity sensor
• Measurement range: 400 ppm – 2000 ppm
• Accuracy: ±(50 ppm + 5 % of reading)
• Current consumption: 17 mA (meas. rate = 5 s) / 0.5 mA (meas. rate = 5 min)
• Fully calibrated and linearized
• I2C digital interface address 0x62
• Sensor Element Size: 10.1mm x 10.1mm x 6.5 mm[
• Product Dimensions: 25.5mm x 22.8mm x 7.7mm / 1.0" x 0.9" x 0.3"
• Product Weight: 2.8g / 0.1oz
• Code: 5187

Packing List:

• 1x Adafruit SCD-40
• header pins