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Arduino Compatible CO2 Sensor – SG112A

SG112A CO2 Sensor

The SG112A is a new low cost, low power NDIR CO2 sensor, compatible with most Arduino devices. The SG112A only requires 4 pins (TX, RX, +5V and GND).  We have tested the SG112A UART connectivity on various arduino platforms (and it’s older sibling, SG111A) using SoftwareSerial, HardwareSerial and Serial1 (on Leonardo based Atmega32u4 based devices).

Most low end CO2 sensors offered to the Arduino community do not offer precision, stability, repeatability or calibration features. However, the SG112A 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.

The chart below demonstrates the SG112A sensor under test compared to a reference CO2 sensor. This test shows the SG112A tracks very well with the reference sensor.

The dark orange line represents the reference sensor response, while the lighter orange line represents the SG112A sensor.

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 SG112A 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.

The SG112A is compatible with the SG111A firmware. 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 SG112A, please contact us.


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