ESP32/SIM800L T2

// Template ID, Device Name and Auth Token are provided by the Blynk.Cloud
// See the Device Info tab, or Template settings
#define BLYNK_TEMPLATE_ID "TMPL24lTb8SVL"
#define BLYNK_DEVICE_NAME "Anti intruder theft system"
#define BLYNK_AUTH_TOKEN "a3E3Oed_RIDAy6C3sw-Dl15ab-_iSFUo"

// including all the required library
#define BLYNK_PRINT Serial
#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

#include <SoftwareSerial.h>
//Create software serial object to communicate with SIM800L
SoftwareSerial mySerial(27, 26); //SIM800L Tx & Rx is connected to Arduino #3 & #2

const int blue_led = 25;
const int buzzer = 19;
const int gas_sensor = 32;

LiquidCrystal_I2C lcd(0x27, 16, 2);  // I2C LCD address and dimensions

int previousDistance = 0;
int buzzerBeepDuration = 0;

char auth[] = BLYNK_AUTH_TOKEN;

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "wifi name";
char pass[] = "password";

BlynkTimer timer;

void setup()
{
  Serial.begin(9600);
   //Begin serial communication with Arduino and SIM800L
  mySerial.begin(9600);
  pinMode(buzzer, OUTPUT);
  pinMode(blue_led, OUTPUT);
  pinMode(gas_sensor, INPUT);
  lcd.init();
  // Print a message to the LCD.
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("IOT GAS SYSTEM!");
  lcd.blink();
  delay(2000);
  lcd.setCursor(0, 1);
  lcd.print("Initializing...");
  lcd.blink();
  delay(2000);
  Blynk.begin(auth, ssid, pass);

}

void loop()
{
  Blynk.run();
  // Get the current time in milliseconds
  unsigned long currentTime = millis();
  unsigned long previousTime;
  unsigned long real_time = currentTime / 1000;
  // Check if 1 second (1000 milliseconds) has elapsed
  if (currentTime - previousTime >= 1000)// Update previousTime with the current time
  {
    previousTime = currentTime;
    currentTime = real_time;
    Blynk.virtualWrite(V1, real_time);// Log the real time in seconds to Blynk's virtual pin 1
  }

  // Read gas sensor value
  int gasValue = analogRead(gas_sensor);
  // Map the gas sensor value to a meaningful range (adjust as needed)
  int gasPercentage = map(gasValue, 1840, 4095, 0, 100);
  if (gasPercentage < 0) {gasPercentage = 0;}
    Blynk.virtualWrite(V0, gasPercentage);
    Serial.print(real_time);
    Serial.print("sec  ");
    Serial.print("Gas Percentage: ");
    Serial.print(gasPercentage);
    Serial.println("%");
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Monitoring now:");
    lcd.setCursor(0, 1);
    lcd.print("Gas Level: "); // Update distance value on LCD
    lcd.print(gasPercentage);
    lcd.print("%");
    lcd.blink();

//    if (gasPercentage > 35)
//    {
//      // If distance is less than 35%, turn on the LED and adjust the buzzer duration
//      digitalWrite(blue_led, HIGH);
//      digitalWrite(buzzer, HIGH);
//    }
//    else  // If distance is greater than or equal to 30 cm, turn off the LED and reset the buzzer duration
//    {
//      digitalWrite(blue_led, LOW);
//      digitalWrite(buzzer, LOW);
//    }
      if (gasPercentage > 50)
  {

  mySerial.println("AT"); //Once the handshake test is successful, it will back to OK
  updateSerial();
  mySerial.println("AT+CMGF=1"); // Configuring TEXT mode
  updateSerial();
  mySerial.println("AT+CMGS=\"+2348096283289\"");//change ZZ with country code and xxxxxxxxxxx with phone number to sms
  updateSerial();
  mySerial.print("Good day sir! Gas threshold is above 50%."); //text content
  updateSerial();
  mySerial.write(26);
  digitalWrite (blue_led, HIGH );
  delay (2000);
  Serial.println("SMS sent succesfully!");
  for(int a =0;a<8;a++)
  {
  tone (buzzer,31,500);
  digitalWrite (blue_led, HIGH );
  delay(500);
  noTone(buzzer);
  digitalWrite (blue_led,LOW);
  delay(500);
  }
 }
 delay(100);  // Delay for stability

}
void updateSerial()
{
  delay(500);
  while (Serial.available())
  {
    mySerial.write(Serial.read());//Forward what Serial received to Software Serial Port
  }
  while(mySerial.available())
  {
    Serial.write(mySerial.read());//Forward what Software Serial received to Serial Port
  }
}