CO2 Click is a compact add-on board that contains Sensirion’s miniature CO2 sensor. This board features the STC31, a gas concentration sensor designed for high-volume applications. The STC31 utilizes a revolutionized thermal conductivity measurement principle, which results in superior repeatability and long-term stability. The outstanding performance of these sensors is based on Sensirion’s patented CMOSens® sensor technology, which combines the sensor element, signal processing, and digital calibration on a small CMOS chip. It features a digital I2C interface, which makes it easy to connect directly to MCU. This Click board™ represents an ideal choice for health, environmental, industrial, residential monitoring of high CO2 concentrations and applications where reliability is crucial.

CO2 Click as its foundation uses the STC31, a gas concentration sensor for high range, accurate CO2 measurements designed for high-volume applications from Sensirion. The STC31 is based on a revolutionized thermal conductivity measurement principle, which results in superior repeatability and long-term stability. By relying on the thermal conductivity technology, the sensor offers an ultra-low power consumption, making the STC31 the perfect choice for applications where reliability is key.

The accuracy of the STC31 is 0.5 vol%, and ±3% of the measured value, while the sensor response time is faster than 1 second. The outstanding performance of these sensors is based on Sensirion’s patented CMOSens® Technology, which combines the sensor element, signal processing, and digital calibration on a small CMOS chip. The well-proven CMOSens® Technology represents the ideal choice for demanding and cost-sensitive OEM applications.

CO2 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Standard Mode operation with a clock frequency up to 100kHz, Fast Mode up to 400kHz, and Fast Mode Plus up to 1MHz. Besides, it also allows the choice of the three least significant bits of its I2C peripheral address by positioning the SMD jumper labeled as ADDR SEL to an appropriate position providing the user with a choice of 4 I2C peripheral addresses.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. However, the Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

• Interface: I²C
• Compatibility: mikroBUS™
• Dimensions: 28.6 x 25.4mm
• Input Voltage: 3.3V or 5V
• Selectable Measurement Range (N2 / Air): Min. 0 vol%, Max. 25/100 vol%
• Accuracy: ±0.5%
• Resolution: 16 bit
• Operating Temperature Range: Min. -20°C, Typ. +25°C, Max. +85°C

• Schematic
• STC31 Datasheet
• mikroSDK
• GitHub