MQ135 AirQuality Sensor migrate sketch to MySensors 2.0



  • hello,

    i would like to build a MQ135 AirQuality Sensor. The sketch i have found from empierre ist not compatible with the 2.0 libery. I don`t know what i musst change on this sketch. Can anyone help me?

    /*
      Arduino MQ135
      connect the sensor as follows :
      A H A   >>> 5V
      B       >>> A0
      H       >>> GND
      B       >>> 10K ohm >>> GND
     
      Contribution: epierre
      Based on David Gironi http://davidegironi.blogspot.fr/2014/01/cheap-co2-meter-using-mq135-sensor-with.html
      http://skylink.dl.sourceforge.net/project/davidegironi/avr-lib/avr_lib_mq135_01.zip
     
    */
    
    #include <SPI.h>
    #include <MySensor.h>  
    #include <Wire.h> 
    
    #define CHILD_ID_AIQ 0
    #define AIQ_SENSOR_ANALOG_PIN 0
    
    #define MQ135_DEFAULTPPM 399 //default ppm of CO2 for calibration
    #define MQ135_DEFAULTRO 68550 //default Ro for MQ135_DEFAULTPPM ppm of CO2
    #define MQ135_SCALINGFACTOR 116.6020682 //CO2 gas value
    #define MQ135_EXPONENT -2.769034857 //CO2 gas value
    #define MQ135_MAXRSRO 2.428 //for CO2
    #define MQ135_MINRSRO 0.358 //for CO2
    
    unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in seconds)
    //VARIABLES
    float mq135_ro = 10000.0;    // this has to be tuned 10K Ohm
    int val = 0;                 // variable to store the value coming from the sensor
    float valAIQ =0.0;
    float lastAIQ =0.0;
    
    MySensor gw;
    MyMessage msg(CHILD_ID_AIQ, V_LEVEL);
    
    void setup()  
    {
      gw.begin();
    
      // Send the sketch version information to the gateway and Controller
      gw.sendSketchInfo("AIQ Sensor MQ135", "1.0");
    
      // Register all sensors to gateway (they will be created as child devices)
      gw.present(CHILD_ID_AIQ, S_AIR_QUALITY);  
       
    }
    
    /*
     * get the calibrated ro based upon read resistance, and a know ppm
     */
    long mq135_getro(long resvalue, double ppm) {
    return (long)(resvalue * exp( log(MQ135_SCALINGFACTOR/ppm) / MQ135_EXPONENT ));
    }
    
    /*
     * get the ppm concentration
     */
    double mq135_getppm(long resvalue, long ro) {
    double ret = 0;
    double validinterval = 0;
    validinterval = resvalue/(double)ro;
    if(validinterval<MQ135_MAXRSRO && validinterval>MQ135_MINRSRO) {
    ret = (double)MQ135_SCALINGFACTOR * pow( ((double)resvalue/ro), MQ135_EXPONENT);
    }
    return ret;
    }
    
    void loop()      
    {    
      uint16_t valr = analogRead(AIQ_SENSOR_ANALOG_PIN);// Get AIQ value
      Serial.println(val);
      uint16_t val =  ((float)22000*(1023-valr)/valr); 
      //during clean air calibration, read the Ro value and replace MQ135_DEFAULTRO value with it, you can even deactivate following function call.
      mq135_ro = mq135_getro(val, MQ135_DEFAULTPPM);
      //convert to ppm (using default ro)
      valAIQ = mq135_getppm(val, MQ135_DEFAULTRO);
    
      Serial.print ( "Val / Ro / value:");
      Serial.print ( val);
      Serial.print ( " / ");
      Serial.print ( mq135_ro);
      Serial.print ( " / ");
      Serial.print ( valAIQ);
    
     
      if (valAIQ != lastAIQ) {
          gw.send(msg.set(MQ135_DEFAULTPPM+(int)ceil(valAIQ)));
          lastAIQ = ceil(valAIQ);
      }
     
      // Power down the radio.  Note that the radio will get powered back up
      // on the next write() call.
      gw.sleep(SLEEP_TIME); //sleep for: sleepTime
    }
    
     
    /*****************************  MQGetPercentage **********************************
    Input:   rs_ro_ratio - Rs divided by Ro
             pcurve      - pointer to the curve of the target gas
    Output:  ppm of the target gas
    Remarks: By using the slope and a point of the line. The x(logarithmic value of ppm) 
             of the line could be derived if y(rs_ro_ratio) is provided. As it is a 
             logarithmic coordinate, power of 10 is used to convert the result to non-logarithmic 
             value.
    ************************************************************************************/ 
    int  MQGetPercentage(float rs_ro_ratio, float ro, float *pcurve)
    {
      return (double)(pcurve[0] * pow(((double)rs_ro_ratio/ro), pcurve[1]));
    }
    

  • Hero Member

    @scaleoblack

    Try this

    /*
      Arduino MQ135
      connect the sensor as follows :
      A H A   >>> 5V
      B       >>> A0
      H       >>> GND
      B       >>> 10K ohm >>> GND
     
      Contribution: epierre
      Based on David Gironi http://davidegironi.blogspot.fr/2014/01/cheap-co2-meter-using-mq135-sensor-with.html
      http://skylink.dl.sourceforge.net/project/davidegironi/avr-lib/avr_lib_mq135_01.zip
     
    */
    
    // Enable debug prints
    #define MY_DEBUG
    
    // Enable and select radio type attached
    #define MY_RADIO_NRF24
    //#define MY_RADIO_RFM69
    
    
    // #include <SPI.h>    
    //#include <MySensor.h>
    #include <MySensors.h>
    #include <Wire.h> 
    
    #define CHILD_ID_AIQ 0
    #define AIQ_SENSOR_ANALOG_PIN 0
    
    #define MQ135_DEFAULTPPM 399 //default ppm of CO2 for calibration
    #define MQ135_DEFAULTRO 68550 //default Ro for MQ135_DEFAULTPPM ppm of CO2
    #define MQ135_SCALINGFACTOR 116.6020682 //CO2 gas value
    #define MQ135_EXPONENT -2.769034857 //CO2 gas value
    #define MQ135_MAXRSRO 2.428 //for CO2
    #define MQ135_MINRSRO 0.358 //for CO2
    
    unsigned long SLEEP_TIME = 30000; // Sleep time between reads (in seconds)
    //VARIABLES
    float mq135_ro = 10000.0;    // this has to be tuned 10K Ohm
    int val = 0;                 // variable to store the value coming from the sensor
    float valAIQ =0.0;
    float lastAIQ =0.0;
    
    // MySensor gw;
    MyMessage msg(CHILD_ID_AIQ, V_LEVEL);
    
    void setup()  
    {
    //  gw.begin();
    
      // Send the sketch version information to the gateway and Controller
     // gw.sendSketchInfo("AIQ Sensor MQ135", "1.0");
    
      // Register all sensors to gateway (they will be created as child devices)
    //  gw.present(CHILD_ID_AIQ, S_AIR_QUALITY);  
       
    }
    
    void presentation()
    {
      // Send the sketch version information to the gateway and Controller
      sendSketchInfo("AIQ Sensor MQ135", "1.0");
     
      // Register all sensors to gw (they will be created as child devices)
      present(CHILD_ID_AIQ, S_AIR_QUALITY);  
    }
    
    /*
     * get the calibrated ro based upon read resistance, and a know ppm
     */
    long mq135_getro(long resvalue, double ppm) {
    return (long)(resvalue * exp( log(MQ135_SCALINGFACTOR/ppm) / MQ135_EXPONENT ));
    }
    
    /*
     * get the ppm concentration
     */
    double mq135_getppm(long resvalue, long ro) {
    double ret = 0;
    double validinterval = 0;
    validinterval = resvalue/(double)ro;
    if(validinterval<MQ135_MAXRSRO && validinterval>MQ135_MINRSRO) {
    ret = (double)MQ135_SCALINGFACTOR * pow( ((double)resvalue/ro), MQ135_EXPONENT);
    }
    return ret;
    }
    
    void loop()      
    {    
      uint16_t valr = analogRead(AIQ_SENSOR_ANALOG_PIN);// Get AIQ value
      Serial.println(val);
      uint16_t val =  ((float)22000*(1023-valr)/valr); 
      //during clean air calibration, read the Ro value and replace MQ135_DEFAULTRO value with it, you can even deactivate following function call.
      mq135_ro = mq135_getro(val, MQ135_DEFAULTPPM);
      //convert to ppm (using default ro)
      valAIQ = mq135_getppm(val, MQ135_DEFAULTRO);
    
      Serial.print ( "Val / Ro / value:");
      Serial.print ( val);
      Serial.print ( " / ");
      Serial.print ( mq135_ro);
      Serial.print ( " / ");
      Serial.print ( valAIQ);
    
     
      if (valAIQ != lastAIQ) {
        //  gw.send(msg.set(MQ135_DEFAULTPPM+(int)ceil(valAIQ)));
           send(msg.set(MQ135_DEFAULTPPM+(int)ceil(valAIQ)));
          lastAIQ = ceil(valAIQ);
      }
     
      // Power down the radio.  Note that the radio will get powered back up
      // on the next write() call.
      //gw.sleep(SLEEP_TIME); //sleep for: sleepTime
      sleep(SLEEP_TIME); //sleep for: sleepTime
    }
    
     
    /*****************************  MQGetPercentage **********************************
    Input:   rs_ro_ratio - Rs divided by Ro
             pcurve      - pointer to the curve of the target gas
    Output:  ppm of the target gas
    Remarks: By using the slope and a point of the line. The x(logarithmic value of ppm) 
             of the line could be derived if y(rs_ro_ratio) is provided. As it is a 
             logarithmic coordinate, power of 10 is used to convert the result to non-logarithmic 
             value.
    ************************************************************************************/ 
    int  MQGetPercentage(float rs_ro_ratio, float ro, float *pcurve)
    {
      return (double)(pcurve[0] * pow(((double)rs_ro_ratio/ro), pcurve[1]));
    }
    


  • thank you. it works:)


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