Diff: MQ135.h

Revision:

0:a43405a3d273

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/MQ135.h	Thu Sep 08 14:05:33 2016 +0000
@@ -0,0 +1,53 @@
+/**************************************************************************/
+/*!
+@file     MQ135.h
+@author   G.Krocker (Mad Frog Labs)
+@license  GNU GPLv3
+
+First version of an Arduino Library for the MQ135 gas sensor
+TODO: Review the correction factor calculation. This currently relies on
+the datasheet but the information there seems to be wrong.
+
+@section  HISTORY
+
+v1.0 - First release
+*/
+/**************************************************************************/
+#ifndef MQ135_H
+#include "mbed.h"
+
+#define MQ135_H
+
+/// The load resistance on the board
+#define RLOAD 10.0
+/// Calibration resistance at atmospheric CO2 level
+#define RZERO 76.63
+/// Parameters for calculating ppm of CO2 from sensor resistance
+#define PARA 116.6020682
+#define PARB 2.769034857
+
+/// Parameters to model temperature and humidity dependence
+#define CORA 0.00035
+#define CORB 0.02718
+#define CORC 1.39538
+#define CORD 0.0018
+
+/// Atmospheric CO2 level for calibration purposes
+#define ATMOCO2 397.13
+
+class MQ135 {
+ private:
+  PinName _pin;
+
+ public:
+  MQ135(PinName pin);
+  ~MQ135();
+  float getCorrectionFactor(float t, float h);
+  float getResistance();
+  float getCorrectedResistance(float t, float h);
+  float getPPM();
+  float getCorrectedPPM(float t, float h);
+  float getRZero();
+  float getCorrectedRZero(float t, float h);
+};
+#endif