MG811 CO2 wiring help Arduino

Question

I have a CO2 sensor with 4 pins. VCC, DOUT,AOUT, GND. Where does the VCC, AOUT, and DOUT wire to? I found no wiring manual when I purchased this sensor off of ebay. I have gone to this link where someone is using the same sensor. However, I don't follow his path considering the third pin (red) isnt going anywhere. It just leads out and stops. http://middlewaresensing.files.wordpress.com/2010/08/100708144455.png

Can anyone spell it out for me clearly for me please?

GND - wires to GROUND
Vcc - Wires to ?
AOUT - Wires to?
DOUT - Wires to?

Answer 1

• GND -> negative
• VCC -> positive (voltage/current depends on sensor)
• AOUT -> analogOut, goes to a analogInput if you want to read the sensor that way. Pay attention that arduino can read at max AREF volt, by default AREF = AVCC = VCC = 5V (please note, taht is vcc of arduino, not of the sensor)
• DOUT -> digitalOut, goes to a pin depending on protocol used, because it is one wire, it can be something like "OneWire",

Voltage and current needed by VCC, and voltage/current ouputted by AOUT and protocol used by DOUT can be extrapolated only by datasheet.

Please note on image he use a arduino nano that exista at 3.3V and 5V, also seems wrong as these kind of sensor normally use a lot of current, witch arduino alone cannot supply

Since it is a MG811, a bit of google search give that tutorial: http://sandboxelectronics.com/?p=147