Diff: MQ2.cpp

Revision:

3:ed294e830904

Parent:

2:05d00b8b071d

Child:

4:48545e508081

--- a/MQ2.cpp	Fri Oct 06 07:38:25 2017 +0000
+++ b/MQ2.cpp	Fri Oct 06 07:51:13 2017 +0000
@@ -43,8 +43,8 @@
          across the load resistor and its resistance, the resistance of the sensor
          could be derived.
 ************************************************************************************/ 
-float MQ2::MQResistanceCalculation(int raw_adc) {
-   return (((float)RL_VALUE*(1023-raw_adc)/raw_adc));
+float MQ2::MQResistanceCalculation(float raw_adc) {
+   return (((float)RL_VALUE*(1-raw_adc)/raw_adc));
 }
 
 /***************************** MQCalibration ****************************************
@@ -55,14 +55,14 @@
          and then divides it with RO_CLEAN_AIR_FACTOR. RO_CLEAN_AIR_FACTOR is about 
          10, which differs slightly between different sensors.
 ************************************************************************************/ 
-float MQ2::MQCalibration() {                                                    // This should be done in 'clean air'
+float MQ2::MQCalibration() {                                                            // This should be done in 'clean air'
   float val=0;
-  for (int i=0;i<CALIBARAION_SAMPLE_TIMES;i++) {                                //take multiple samples
-    val += MQResistanceCalculation(_pin.read_u16()>>6);
+  for (int i=0;i<CALIBARAION_SAMPLE_TIMES;i++) {                                        //take multiple samples
+    val += MQResistanceCalculation(_pin.read());
     wait_ms(CALIBRATION_SAMPLE_INTERVAL);
   }
-  val = val/CALIBARAION_SAMPLE_TIMES;                                           //calculate the average value
-  val = val/RO_CLEAN_AIR_FACTOR;                                                //divided by RO_CLEAN_AIR_FACTOR yields the Ro according to the chart in the datasheet 
+  val = val/CALIBARAION_SAMPLE_TIMES;                                                   //calculate the average value
+  val = val/RO_CLEAN_AIR_FACTOR;                                                        //divided by RO_CLEAN_AIR_FACTOR yields the Ro according to the chart in the datasheet 
   return val; 
 }
 
@@ -78,7 +78,7 @@
   int i;
   float rs=0;
   for (i=0;i<READ_SAMPLE_TIMES;i++) {
-    rs += MQResistanceCalculation(_pin.read_u16()>>6);
+    rs += MQResistanceCalculation(_pin.read());
     wait_ms(READ_SAMPLE_INTERVAL);
   }
   rs = rs/READ_SAMPLE_TIMES;