Renan Alves / MQ4

This library is made for MQ-4 gás sensor.

Dependents:   MQ4_example Navitec-Firmware

MQ4.h@0:401959f72658, 2018-07-17 (annotated)

Committer:
renanbmx123
Date:
Tue Jul 17 04:34:21 2018 +0000
Revision:
0:401959f72658
Library for Mq4 gas sensor

Who changed what in which revision?

UserRevisionLine numberNew contents of line
renanbmx123 0:401959f72658 1 #ifndef MQ4_h
renanbmx123 0:401959f72658 2 #define MQ4_h
renanbmx123 0:401959f72658 3
renanbmx123 0:401959f72658 4 #include "mbed.h"
renanbmx123 0:401959f72658 5
renanbmx123 0:401959f72658 6 #define RL_VALUE 10 //define the load resistance on the board, in kilo ohms
renanbmx123 0:401959f72658 7 #define RO_DEFAULT 10 //Ro is initialized to 10 kilo ohms
renanbmx123 0:401959f72658 8 #define RO_CLEAN_AIR_FACTOR 4.4f //RO_CLEAR_AIR_FACTOR=(Sensor resistance in clean air)/RO, which is derived from the chart in datasheet
renanbmx123 0:401959f72658 9 #define CALIBARAION_SAMPLE_TIMES 5 //define how many samples you are going to take in the calibration phase
renanbmx123 0:401959f72658 10 #define CALIBRATION_SAMPLE_INTERVAL 50 //define the time interal(in milisecond) between each samples
renanbmx123 0:401959f72658 11 #define READ_SAMPLE_INTERVAL 50 //define how many samples you are going to take in normal operation
renanbmx123 0:401959f72658 12 #define READ_SAMPLE_TIMES 5 //define the time interal(in milisecond) between each samples
renanbmx123 0:401959f72658 13
renanbmx123 0:401959f72658 14 //The curves
renanbmx123 0:401959f72658 15 // {log(X1) ,log(Y),[log(Y1) - log(Y2)] / [log(X2) - log(X1)]} get values from datasheet
renanbmx123 0:401959f72658 16 static float LPGCurve[] = {2.3f,0.43f,-0.33f};
renanbmx123 0:401959f72658 17 static float H2Curve[] = {2.3f,0.57f,-0.16f};
renanbmx123 0:401959f72658 18 static float CH4Curve[] = {2.3f,0.27f,-0.38f};
renanbmx123 0:401959f72658 19
renanbmx123 0:401959f72658 20 typedef struct {
renanbmx123 0:401959f72658 21 float lpg;
renanbmx123 0:401959f72658 22 float h2;
renanbmx123 0:401959f72658 23 float ch4;
renanbmx123 0:401959f72658 24 } MQ4_data_t;
renanbmx123 0:401959f72658 25
renanbmx123 0:401959f72658 26 typedef enum {
renanbmx123 0:401959f72658 27 GAS_LPG = 0,
renanbmx123 0:401959f72658 28 GAS_H2 = 1,
renanbmx123 0:401959f72658 29 GAS_CH4 = 2
renanbmx123 0:401959f72658 30 } GasType;
renanbmx123 0:401959f72658 31
renanbmx123 0:401959f72658 32
renanbmx123 0:401959f72658 33 class MQ4 {
renanbmx123 0:401959f72658 34 public:
renanbmx123 0:401959f72658 35 MQ4(PinName pin) : _pin(pin){
renanbmx123 0:401959f72658 36 Ro = RO_DEFAULT;
renanbmx123 0:401959f72658 37 };
renanbmx123 0:401959f72658 38 void read(MQ4_data_t *ptr);
renanbmx123 0:401959f72658 39 float readLPG();
renanbmx123 0:401959f72658 40 float readH2();
renanbmx123 0:401959f72658 41 float readCH4();
renanbmx123 0:401959f72658 42 float get_Ro();
renanbmx123 0:401959f72658 43 void begin();
renanbmx123 0:401959f72658 44 private:
renanbmx123 0:401959f72658 45 AnalogIn _pin;
renanbmx123 0:401959f72658 46 float MQRead();
renanbmx123 0:401959f72658 47 float MQGetGasPercentage(float rs_ro_ratio, GasType gas_id);
renanbmx123 0:401959f72658 48 int MQGetPercentage(float rs_ro_ratio, float *pcurve);
renanbmx123 0:401959f72658 49 float MQCalibration();
renanbmx123 0:401959f72658 50 float MQResistanceCalculation(int raw_adc);
renanbmx123 0:401959f72658 51 float Ro;
renanbmx123 0:401959f72658 52
renanbmx123 0:401959f72658 53 };
renanbmx123 0:401959f72658 54
renanbmx123 0:401959f72658 55 #endif