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Arduino CO2 Sensor – SG111A

SG111A CO2 Sensor

The SG111A is a new low cost, low power NDIR CO2 sensor, compatible with many Arduino devices. Most MOS CO2 sensors available to the Arduino community do not offer precision, stability, repeatability or calibration features. However, the SG111A NDIR sensor solves all those problems by offering good precision, factory calibration and easy integration at a very affordable price. The sensor is a dual channel NDIR CO2 sensor module with 400-5000PPM range (10,000 PPM optional). The sensor can communicate with a host device via UART or PWM output.

For full specifications, download the full datasheet here:

We ran this sensor in-house for several weeks for comparison tests with several reference sensors. We also exposed this sensor to a wide range of temperature and humidity, calibration gas concentrations and common cross sensitivities.

The chart below demonstrates the SG111A sensor under test compared to a reference CO2 sensor. This test shows the SG111A tracks very well with the reference sensor.

Chart comparing the SG111A sensor output to a reference sensor (chart derived from Aretas IoT Cloud Software)

Since the sensor is factory calibrated, you don’t need to worry about interpreting the data or creating your own calibration functions. We also exposed the sensor to standard calibration gases and regression analysis.

Connecting the SG111A to an Arduino is very easy and requires only 4 pins on the SG111A sensor (+5V, GND and TX/RX).

Since the SG111A UART is only 9600 bps, you can use a SoftwareSerial port on the Arduino to communicate with the CO2 sensor and use Hardware Serial for viewing the output.

The sensor (by default) emits a CO2 reading via UART every 2 seconds.

To see the output from the sensor, download the SG111A-Test-Sketch from our GitHub repo for the sensor. Make sure to adjust the SofwareSerial pins to match your connection! The diagram and the sample sketch may not match!

A full Arduino library is coming soon along with sample code and methods to hook up to your PC (via FTDI adapter) and other devices.

For information on how to purchase the SG111A, please contact us.


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