Using Seeed Studio O2 Sensor Arduino Without Grove Breakout board

The Seeed Studio O2 sensor is a nice Oxygen sensor. It works up to 25% Oxygen concentration and is easy to use in an Arduino project.

Wiring Up the O2 Sensor to Arduino

If you look on the back of the sensor there are only 3 wires used. VCC, GND, and a SIG. The NC pin is “Not Connected”

Wire the
GND -> Arduino ground
VCC -> Arduino 3.3V (Looks like it may also accept 5V)
SIG -> A5 (Analog 5)

Code to read O2 Sensor

Copy and paste the following code into the Arduino IDE

// Grove - Gas Sensor(O2) test code
// Note:
// 1. It need about about 5-10 minutes to preheat the sensor
// 2. modify VRefer if needed

const float VRefer = 3.3;       // voltage of adc reference

const int pinAdc   = A5;

void setup() 
    // put your setup code here, to run once:
    Serial.println("Grove - Gas Sensor Test Code...");

void loop() 
    // put your main code here, to run repeatedly:
    float Vout =0;
    Serial.print("Vout =");

    Vout = readO2Vout();
    Serial.print(" V, Concentration of O2 is ");

float readO2Vout()
    long sum = 0;
    for(int i=0; i<32; i++)
        sum += analogRead(pinAdc);
    sum >>= 5;
    float MeasuredVout = sum * (VRefer / 1023.0);
    return MeasuredVout;

float readConcentration()
    // Vout samples are with reference to 3.3V
    float MeasuredVout = readO2Vout();
    //float Concentration = FmultiMap(MeasuredVout, VoutArray,O2ConArray, 6);
    //when its output voltage is 2.0V,
    float Concentration = MeasuredVout * 0.21 / 2.0;
    float Concentration_Percentage=Concentration*100;
    return Concentration_Percentage;

Upload and Launch the Serial Monitor
Tools -> Serial Monitor
Ctrl + Shift + M