I purchased this CO2 sensor a while back: SainSmart MG811 Gas CO2 Carbon Dioxide Sensor Module Sensor Module for Arduino UNO R3 Raspberry Pi
The module has four pins, Vin, GND, Dout and Aout. I assume Dout and Aout are digital output and analog output, respectively.
Other than that, the sensor came with no datasheet, instructions, or tutorial. I also searched online but fail to find anything useful.
I'm going simple for now, just hooking up the sensor module to Arduino board. I know I can probably connect the output pins to the analog pins, and analogRead them, but what I am looking for is how to convert the raw data readings into CO2 levels in PPM. Like a formula.
Also, I'm curious as to how the digital output works...