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Change correction formula

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This commit is contained in:
Dmitry Frolov 2015-07-09 22:20:55 +06:00
parent d39b92dba0
commit 45d730d85c
2 changed files with 8 additions and 1 deletions
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7
MQ135.cpp
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@ -50,7 +50,12 @@ MQ135::MQ135(uint8_t pin, float rload, float rzero, float atmoco2, float vref, f
*/ */
/**************************************************************************/ /**************************************************************************/
float MQ135::getCorrectionFactor(float t, float h) { float MQ135::getCorrectionFactor(float t, float h) {
return CORA * t * t - CORB * t + CORC - (h-33.)*CORD; //return CORA * t * t - CORB * t + CORC - (h-33.)*CORD;
// This formula is reduced from temperature and humidity dependency graph,
// found in this datasheet:
// http://china-total.com/Product/meter/gas-sensor/MQ135.pdf
return (1.30732 - 0.0116044 * t) * (2.20591 - 0.296456 * log(h));
} }
/**************************************************************************/ /**************************************************************************/

2
MQ135.h
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@ -31,11 +31,13 @@ v1.0 - First release
#define PARA 117.185 #define PARA 117.185
#define PARB 2.65797 #define PARB 2.65797
/*
/// Parameters to model temperature and humidity dependence /// Parameters to model temperature and humidity dependence
#define CORA 0.00035 #define CORA 0.00035
#define CORB 0.02718 #define CORB 0.02718
#define CORC 1.39538 #define CORC 1.39538
#define CORD 0.0018 #define CORD 0.0018
*/
/// Atmospheric CO2 level for calibration purposes, in PPM. /// Atmospheric CO2 level for calibration purposes, in PPM.
/// See http://co2now.org/ /// See http://co2now.org/