AQE Sensor Interface Shield vicatcu

aqe-sensor-interface-shield / AirQualityEggNanode / sensors.ino

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/* sensor vars and read functions */

//debounce time (milliseconds) between each analog sensor reading
const int sensorDebounceTime = 15;

int tmp102Address = 0x48; //temp sensor 2-wire address

CS_MQ7 MQ7(4);  //sensor "tog" pin on 4

void readSensors(){
  //sensors
  Serial.println("reading sensors");
  currNo2 = getNo2();
  delay(sensorDebounceTime);
  currCo = getCO();
  delay(sensorDebounceTime);
  currQuality = getQuality();
  delay(sensorDebounceTime);
  currHumidity = getHumidity();
  delay(sensorDebounceTime);
  currTemp = getTemperature();
  delay(sensorDebounceTime);
  
  MQ7.CoPwrCycler(); //for CO sensor power cycling
}

//--------- e2v MiCS-2170 NO2 sensor ---------
int getNo2(){
  int thisReading = 10;

  //set reference voltage to 3.3 here?
  thisReading = analogRead(No2SensorPin);
  return thisReading;
}

//--------- MQ-7 carbon monixide sensor ---------
//breakout info: http://citizensensor.cc/make
int getCO(){
  int thisReading = 11;

    if (MQ7.currentState() == LOW){ //not heating, ready to read.
      thisReading = analogRead(CoSensorPin);
    } 
    else { //heating, leave value where it was
      thisReading = currCo;
    }

  return thisReading;
}

//--------- MQ-135 air quality sensor ---------
int getQuality(){
  int thisReading = 12;

  thisReading = analogRead(qualitySensorPin);
  return thisReading;
}

//--------- Sparkfun humidity sensor ---------
int getHumidity(){
  int thisReading = 13;

  thisReading = analogRead(humiditySensorPin);
  return thisReading;
}

//--------- Sparkfun i2c temperature sensor ---------
int getTemperature(){
  int thisReading = 14;
  Wire.requestFrom(tmp102Address,2); 

  byte MSB = Wire.read();
  byte LSB = Wire.read();

  //it's a 12bit int, using two's compliment for negative
  int TemperatureSum = ((MSB << 8) | LSB) >> 4; 

  float celsius = TemperatureSum*0.0625;

  thisReading = int(celsius);

  return thisReading;
}