SparkFun

SparkFun CO₂ Humidity and Temperature Sensor - SCD40 (Qwiic)

Name: SparkFun CO₂ Humidity and Temperature Sensor - SCD40 (Qwiic)
Brand: SparkFun
SKU: SF-SEN-22395
Price: 208.15 AUD
Availability: InStock

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$208.15 |

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The SparkFun SCD40 breakout board measures CO₂ concentration, humidity, and temperature using Sensirion's PASens photoacoustic measurement technology. The se...

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The SparkFun SCD40 breakout board measures CO₂ concentration, humidity, and temperature using Sensirion's PASens photoacoustic measurement technology. The sensor detects CO₂ from 0 to 40,000 ppm with high accuracy over the 400–2,000 ppm range, and includes an integrated CMOSens temperature and humidity sensor for improved readings.

The board connects via I2C through two Qwiic connectors or a standard 2.54 mm (0.1″) header. An automatic self-calibration routine adjusts accuracy over a seven-day period — Sensirion recommends at least one hour of fresh-air readings per day during calibration. The sensor also accepts ambient pressure input for additional accuracy compensation.

Key Features

Sensirion SCD40 – Photoacoustic CO₂ sensor with integrated temperature and humidity
CO₂ Range – 0–40,000 ppm
CO₂ Accuracy – ±(50 ppm + 5% of reading) over 400–2,000 ppm
Humidity – 0–100% RH, ±9% RH accuracy
Temperature – −10 to +60°C, ±1.5°C accuracy
I2C Interface – Address 0x62, dual Qwiic connectors + breakout header
2.4–5.5V Supply – 3.3V typical
Low Power Modes – Normal: 18 mA typical, low power: 3.5 mA, single-shot: 0.5 mA
Auto Self-Calibration – Seven-day calibration routine for optimal accuracy

Ideal For

Indoor air quality monitoring
HVAC and ventilation control systems
Environmental sensing projects
Smart building and classroom CO₂ tracking

Resources

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Plain-language definitions for the technical terms used above.

Automatic Self-Calibration: Automatic Self-Calibration is a built-in routine that adjusts the sensor over time to reduce drift in its readings. It matters for long-running indoor monitors because it can help keep measurements stable without frequent manual calibration.
breakout: A breakout board carries a small or fine-pitched component and brings its connections out to standard, breadboard- and header-friendly pins. Describing a part as a breakout means it can be wired into a project without soldering directly to the component's tiny contacts.
CMOSens: CMOSens is Sensirion’s integrated sensor technology that combines sensing elements and electronics in one package. It matters because it affects how the sensor measures temperature and humidity and how it is supported by the manufacturer’s libraries and datasheets.
I2C: I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
PASens: PASens is Sensirion’s name for its photoacoustic sensing technology used in some CO2 sensors. Knowing this helps explain why the sensor uses light and a microphone internally rather than a simple chemical gas sensor.
photoacoustic measurement: Photoacoustic measurement detects gas by shining light into a sample and listening for tiny pressure waves created when the gas absorbs that light. In a CO2 sensor, this matters because it is the method used to estimate carbon dioxide concentration.
ppm: ppm means parts per million, a common way to express very small gas concentrations in air. For CO₂ sensors, the ppm range tells you what levels the sensor can measure, such as normal indoor air through to poorly ventilated spaces.
Qwiic: Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.