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--- amc2021:groupl:code:carbon_dioxide_measuring [2021/09/04 13:49] – leen001
+++ amc2021:groupl:code:carbon_dioxide_measuring [2023/01/05 14:38] (current) – external edit 127.0.0.1
@@ Line 3: / Line 3: @@
 This code communicates with the MQ135 air quality sensor with the help of the [[amc2021:groupl:extras:mq-135:start|MQ135.h library]]. The sensor is supposed to preheat for 24 hours before taking readings.
 Once the code runs, it prints out the concentration of detected gases in ppm on a serial monitor, and the results are displayed on an LCD screen.
-An alarm system (LED light) is also set to glow if the CO<sub>2<\sub> values cross a threshold value of 1000ppm.
+An alarm system (LED light) is also set to glow if the CO<sub>2</sub> values cross a threshold value of 1000ppm.
 Detailed explanation is given in the [[amc2021:groupl:video:start|video tutorial]]
-<code>
+<file c++ CO2Sensor.ino>
-#include "MQ135.h"
+#include "MQ135.h" //Main library that contains functions to get the ppm values
 #include <Wire.h>
 #include <LiquidCrystal_I2C.h>  //Header file for LCD
@@ Line 15: / Line 15: @@
 LiquidCrystal_I2C lcd(0x27,16,2);//set the LCD address to x27 for a 16 chars and 2 line display
-#define led          9                       //led on pin 9
+#define led          9                  //led on pin 9
-const int gas_pin = A0;                      //analog feed from MQ135
+const int gas_pin = A0;                 //analog feed from MQ135
-MQ135 gasSensor = MQ135(gas_pin);
+MQ135 gasSensor = MQ135(gas_pin);       //Define the gas pin in the function mq135 gas sensor as per the mq135 library
 void setup(){
   lcd.init();                      // initialize the lcd
-  lcd.begin(16,2);                  // consider 16 chars + 2 lines lcd
+  lcd.begin(16,2);                 // consider 16 chars + 2 lines lcd
   lcd.backlight();                 // illuminate to produce visible reading
   lcd.clear();                     // clear lcd
   lcd.setCursor(4,0);              //set cursor of lcd to 1st row and 5th column
-  lcd.print("Group L");          // print as a sentence on lcd
+  lcd.print("Group L");            // print as a sentence on lcd
   pinMode(gas_pin,INPUT);     //MQ135 analog feed set for input
@@ Line 35: / Line 35: @@
 void loop(){
- float ppm = gasSensor.getPPM();
+ float ppm = gasSensor.getPPM(); //function to get ppm value based on the MQ135.h library
  Serial.println(ppm);            // print ppm on serial monitor
  delay(1000);
    lcd.clear();                  // clear lcd
-   lcd.setCursor(0,0);          // set cursor of lcd to 1st row and 1st column
+   lcd.setCursor(0,0);           // set cursor of lcd to 1st row and 1st column
-   lcd.print("Air Quality: ");  // print as a sentence on lcd
+   lcd.print("Air Quality: ");   // print as a sentence on lcd
-   lcd.print(ppm);             // print value of MQ135
+   lcd.print(ppm);               // print value of MQ135
- if(ppm>999){                  //if co2 ppm > 1000
+ if(ppm>999){                    //if co2 ppm > 1000
-    digitalWrite(led,HIGH);    //turn on led
+    digitalWrite(led,HIGH);      //turn on led
-    lcd.setCursor(2,1);        // set cursor of lcd to 2nd row and 3rd column
+    lcd.setCursor(2,1);          // set cursor of lcd to 2nd row and 3rd column
-    lcd.print("AQ Level BAD");  //print as a sentence on lcd
+    lcd.print("AQ Level BAD");   //print as a sentence on lcd
    }
  else{
-    digitalWrite(led,LOW);         //turn off led
+    digitalWrite(led,LOW);       //turn off led
-    lcd.setCursor(1,1);            // set cursor of lcd to 2nd row and 2nd column
+    lcd.setCursor(1,1);          // set cursor of lcd to 2nd row and 2nd column
-    lcd.print ("AQ Level Good");   // print as a sentence on lcd
+    lcd.print ("AQ Level Good"); // print as a sentence on lcd
   }
 }
-</code>
+</file>
+[[amc2021:groupl:report:start|Back to report]]