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The SparkFun CO2, Humidity and Temperature Sensor - SCD4X (Qwiic) breakouts feature the SCD40 and SCD41 CO2 sensors from Sensirion. The SCD4X sensors use Sensirion's PASens photoacoustic measurement system that combines the use of narrow-band IR light and a microphone inside the sensing package that results in a high-quality sensor that measures CO2 concentrations from 0 to 40,000ppm. The sensors also have an integrated humidity and temperature sensor to provide environmental conditions to improve accuracy. The SCD40 has the best accuracy from 400 to 2,000ppm and the SCD41 has the best accuracy from 400 to 5,000ppm.

These sensors also feature automatic self-calibration routines to automatically adjust to their sensing environments over seven day calibration period. For best results, Sensirion recommends taking continuous readings for at least one hour a day of 'fresh air' for the calibration period to complete.

In this guide we'll go over the details of the SCD4x sensors and other hardware present on these breakout boards, how to assemble it into a Qwiic circuit and how to use it with the SparkFun SCD4x Arduino Library.

Required Materials

To follow along with this guide you will need a microcontroller to communicate with these SCD4X breakouts. Below are a few options that come Qwiic-enabled out of the box:

If your chosen microcontroller is not already Qwiic-enabled, you can add that functionality with one or more of the following items:

You will also need at least one Qwiic cable to connect your SCD4X breakout to your microcontroller:

Optional Materials

If you prefer a soldered connection or want to modify the solder jumpers on this board, you may need some of the products listed below:

Suggested Reading

We designed this board for integration into SparkFun's Qwiic connect system. Click on the banner below to learn more about the SparkFun Qwiic Connect System.

Before getting started with this Hookup Guide, you may want to read through the tutorials below if you are not familiar with the concepts covered in them or want a refresher. If you are using either of the Qwiic Shields linked above, we recommend reading through their respective Hookup Guides before continuing with this tutorial: