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--- amc2021:groupl:extras:mq-135:start [2021/09/03 01:59] – kshama001
+++ amc2021:groupl:extras:mq-135:start [2023/01/05 14:38] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== M_Q135.h ======
+ Rzero is the value of the resistor in the MQ-135 sensor in the presence of clean air. Where the CO <sub>2</sub> value is around 400 ppm as given below. The Rzero value varies for each individual sensor and can be found using another Arduino [[amc2021:groupl:extras:r0:start|code]]
+  *RLOAD meanwhile is the external resistor value that is connected to the MQ-135 sensor, which in this case is 10kΩ.
+  *Important parameters are for calculating CO<sub>2</sub> of 116.6 and 2.79 are taken from a calibration graph as seen from the [[https://www.electronicoscaldas.com/datasheet/MQ-135_Hanwei.pdf|datasheet]]. This shows the sensitivity of the sensor varies for each gas.
+{{ :amc2021:groupL:extras:mq-135:screenshot_2021-09-03_at_01.11.54.png |here}}
+From the below code, we replace the Rzero value(which we get with the function getRzero()) and use the float getPPM() to get the level of CO<sub>2</sub>
+<file - M_Q135.h>
 <code>
 /**************************************************************************/
@@ Line 24: / Line 30: @@
 #define RLOAD 10.0
 /// Calibration resistance at atmospheric CO2 level
-#define RZERO 65
+#define RZERO 65 //Dependent on the sensor
 /// Parameters for calculating ppm of CO2 from sensor resistance
 #define PARA 116.6020682
 #define PARB 2.769034857
-</code>
-  *Rzero is the value of the resistor in the MQ-135 sensor in the presence of clean air. Where the CO <sub>2</sub> value is around 397.13 ppm as given below. The Rzero value varies for each individual sensor and can be found using another Arduino [[amc2021:groupl:extras:r0:start|code]]
-  *RLOAD meanwhile is the external resistor value that is connected to the MQ-135 sensor, which in this case is 10kΩ.
-  *Important parameters are for calculating CO<sub>2</sub> of 116.6 and 2.79 are taken from a calibration graph as seen from the [[https://www.electronicoscaldas.com/datasheet/MQ-135_Hanwei.pdf|datasheet]]. This shows the sensitivity of the sensor varies for each gas.
-{{ :amc2021:groupL:extras:mq-135:screenshot_2021-09-03_at_01.11.54.png |here}}
-<code>
 /// Parameters to model temperature and humidity dependence
@@ Line 44: / Line 43: @@
 /// Atmospheric CO2 level for calibration purposes
-#define ATMOCO2 397.13
+#define ATMOCO2 400
 class MQ135 {
@@ Line 62: / Line 61: @@
 #endif
 </code>
+</file>
+[[amc2021:groupl:report:start|Back to report]]