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Respect upper and down limits from datasheet indicating 0 PPM or 9999 PPM

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miguel5612 2019-09-08 12:49:02 -05:00
parent 886bfd9981
commit b2616295a3
2 changed files with 15 additions and 9 deletions
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6
src/MQUnifiedsensor.cpp
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@ -107,8 +107,12 @@ float MQUnifiedsensor::readSensor(String nameLectureRequeired, bool print)
setSensorCharacteristics(nameLectureRequeired, print); //In this function update _a and _b
//More explained in: https://jayconsystems.com/blog/understanding-a-gas-sensor
_RS_Calc = ((_VOLT_RESOLUTION*_RLValue)/_sensor_volt)-_RLValue; //Get value of RS in a gas
if(_RS_Calc < 0) _RS_Calc = 0; //No negative values accepted.
_ratio = _RS_Calc / this->_R0; // Get ratio RS_gas/RS_air
if(_ratio <= 0 || _ratio>100) _ratio = 0.01; //No negative values accepted or upper datasheet recomendation.
_PPM= _a*pow(_ratio, _b);
if(_PPM < 0) _PPM = 0; //No negative values accepted or upper datasheet recomendation.
if(_PPM > 10000) _PPM = 9999; //No negative values accepted or upper datasheet recomendation.
if(print)
{
@ -522,7 +526,9 @@ float MQUnifiedsensor::calibrate(boolean print) {
float RS_air; //Define variable for sensor resistance
float R0; //Define variable for R0
RS_air = ((_VOLT_RESOLUTION*_RLValue)/_sensor_volt)-_RLValue; //Calculate RS in fresh air
if(RS_air < 0) RS_air = 0; //No negative values accepted.
R0 = RS_air/_ratioInCleanAir; //Calculate R0
if(R0 < 0) R0 = 0; //No negative values accepted.
if(print)
{
Serial.println("*******Calibrating*********");

14
src/MQUnifiedsensor.h
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@ -273,14 +273,14 @@ class MQUnifiedsensor
private:
/************************Private vars************************************/
int _pin, _type, _lecturePosInArray;
double _R0;
byte _pin, _type, _lecturePosInArray;
byte _VOLT_RESOLUTION = 5.0; // if 3.3v use 3.3
byte _ratioInCleanAir, _sensor_volt;
byte _RLValue = 10; //Value in KiloOhms
float _R0, RS_air, _ratio, _PPM, _RS_Calc;
float _b;
double _a;
String _nameLectureRequeired;
float _VOLT_RESOLUTION = 5.0; // if 3.3v use 3.3
int _RLValue = 10; //Value in KiloOhms
float _PPM, _RS_Calc;
float _ratioInCleanAir, _sensor_volt, RS_air, _a, _b, _ratio;
};
#endif //MQUnifiedsensor_H