The SCD40 sensor includes an automatic self-calibration routine that adjusts to its environment over a seven-day period. To achieve the best results, it's recommended to take continuous readings for at least an hour a day of 'fresh air' during the calibration period.
SparkFun has developed an Arduino library to simplify reading the CO₂, humidity, and temperature. It can be easily downloaded through the Arduino Library manager by searching for 'SparkFun SCD4x'.
The SparkFun Qwiic Connect System is an ecosystem of I2C sensors, actuators, shields, and cables that make prototyping faster and less prone to error. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector, reducing the amount of required PCB space, and polarized connections mean you can’t connect it incorrectly.
The SparkFun SCD4x CO2 Hookup Guide is available to help you get started with the sensor.
The sensor features an I2C interface and operates on a supply voltage range of 2.4-5.5V, with a typical value of 3.3V. It has a low current consumption, with a maximum of 205mA at 3.3V in normal mode, 18mA typically at 3.3V in normal mode, 3.5mA typically at 3.3V in low power mode, and 0.5mA at 3.3V in single-shot mode. The sensor has a CO2 output range of 0-40,000ppm, a humidity range of 0-100%RH, and a temperature range of -10°C-60°C.
Documentation for the sensor, including the schematic, Eagle files, board dimensions, hookup guide, datasheet, Qwiic information page, SCD4X Arduino Library, and Github hardware repo, is readily available.