IoT Based Air Quality Monitoring

Circuit Diagram :-

Code :-

 
//Prateek
//www.prateeks.in

#include <ESP8266WiFi.h>
#include <SPI.h>
#include <Wire.h>
#include "MQ135.h"
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128    
#define SCREEN_HEIGHT 64    
#define OLED_RESET -1       
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

String apiKey = "3GXEV3B944KWTGQU"; 
const char* ssid = "justDo";  
const char* password = "pratik123";   
const char* server = "api.thingspeak.com";

WiFiClient client;


void setup()
{
  Serial.begin(115200);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); 
  display.clearDisplay();
  delay(10);

  Serial.println("Connecting to ");
  Serial.println(ssid);
  
  display.clearDisplay();
  display.setCursor(0,0);  
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.println("Connecting to ");
  display.setTextSize(2);
  display.print(ssid);
  display.display();
  
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
    Serial.println("");
    Serial.println("WiFi connected");
    
    display.clearDisplay();
    display.setCursor(0,0);  
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.print("WiFi connected");
    display.display();
    delay(4000);
}


  void loop()
  {
    MQ135 gasSensor = MQ135(A0);
    float air_quality = gasSensor.getPPM();
    Serial.print("Air Quality: ");  
    Serial.print(air_quality);
    Serial.println("  PPM");   
    Serial.println();

    display.clearDisplay();
    display.setCursor(0,0);  
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.println("Air Quality Index");
    
  
    display.setCursor(0,20);  
    display.setTextSize(2);
    display.setTextColor(WHITE);
    display.print(air_quality);
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.println(" PPM");
    display.display();


    if (client.connect(server, 80))
  {
    String postStr = apiKey;
    postStr += "&field1=";
    postStr += String(air_quality);
    postStr += "r\n";
    
    client.print("POST /update HTTP/1.1\n");
    client.print("Host: api.thingspeak.com\n");
    client.print("Connection: close\n");
    client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
    client.print("Content-Type: application/x-www-form-urlencoded\n");
    client.print("Content-Length: ");
    client.print(postStr.length());
    client.print("\n\n");
    client.print(postStr);
    
    Serial.println("Data Send to Thingspeak");
  }
    client.stop();
    Serial.println("Waiting...");

    delay(2000);      
}

Photo