Introduction

"Greenhouse Effect" is melting the iceberg every minute,. By knowing the exact concentration of CO2, we can do something to reduce the CO2 and to protect our earth. For that reason, a High quality CO2 sensor is designed by DFRobot eningeer . This is the first CO2 sensor in opensource hardware market. The output voltage of the module falls as the concentration of the CO2 increases. The potentiometer onboard is designed to set the threshold of voltage. Once the CO2 concentration is high enough (voltage is lower than threshold), a digital signal (ON/OFF) will be released.

• It has MG-811 gas sensor onboard which is highly sensitive to CO2 and less sensitive to alcohol and CO, Low humidity&temperature dependency. All components have industrial quality which means stability and reproducibility.
• Onboard heating circuit brings the best temperature for sensor to function. 5V power input will be boosted to 6V for heating.
• This sensor has an onboard conditioning circuit for amplifying output signal.

External power supply (7~12V) is necessary to supply the microcontroller board when you using this CO2 sensor module. This module is an electrochemical sensor, you need to calibrate it before actual measurement.

Specification

• Operating voltage:5V
• Interface:Analog
• One digital output
• High quality connector
• Immersion gold surface
• Onboard heating circuit
• Size:32x42mm

Connecting Diagram

Tutorial

How to use this module? 
It is very easy.
You need to set potentiometer onboard to the threshold value. Just make the red led turn off. With the CO2 concentration is enough high to make the sensor output voltage higher than threshold value,the led will be turned on. If you connect a buzzer to the module(right side), you will hear the alarm.

Calibration

This module is an electrochemistry sensor, you should calibrate it before actual measurement.
You should provide stable power to this module, and the sensor will heating while working. Please put this module into the area where the air is clean. After continuous working about 48 hours, you can measure the output voltage of this module. Then modify the defination in the code with the voltage value(unit:V) divide by 8.5.

#define         ZERO_POINT_VOLTAGE           (voltage/8.5)

For example, the voltage you measured from the module is 2.4V, then 2.4/8.5=0.282. So modify the defination as below:

#define         ZERO_POINT_VOLTAGE           (0.282)

After the modification, upload the sample code to your Arduino board.