HOW to Make a Smoke Alarm with ESP32

//**********************************************************************************
/*  
 * Filename    : smoke alarm
 * Description : MQ2 controls a buzzer and a four-digit analog smoke tester
 * Auther      : http//www.keyestudio.com
*/
#include "TM1650.h" //Import the TM1650 library file
int adcVal = 0; //display ADC value
//the interfaces are GPIO21 and GPIO22
#define DIO 21
#define CLK 22
TM1650 DigitalTube(CLK,DIO);

void setup() {
  DigitalTube.setBrightness();  //set brightness, 0---7, default : 2
  DigitalTube.displayOnOFF();   //display on or off, 0=display off, 1=display on, default : 1
  for(char b=1;b<5;b++){
    DigitalTube.clearBit(b);      //DigitalTube.clearBit(0 to 3); Clear bit display.
  }
  // DigitalTube.displayDot(1,true); //Bit0 display dot. Use before displayBit().
  DigitalTube.displayBit(1,0);    //DigitalTube.Display(bit,number); bit=0---3  number=0---9
  pinMode(15, OUTPUT);//the buzzer is connected to GPIO15
}

void loop() {
  adcVal = analogRead(34);//Read the ADC values of MQ2
  displayFloatNum(adcVal);;//Four digit tube display adcVal values
  if (adcVal > 1000) {//ADC value is greater than 1000
    digitalWrite(15, HIGH); // buzzer alarming
  } else {//or else
    digitalWrite(15, LOW); //Turn off the buzzer
  }
  delay(100);//delay 100ms
}

void displayFloatNum(float adcVal){
  if(adcVal > 9999)
    return;
  int dat = adcVal*10;
   //DigitalTube.displayDot(2,true); //Bit0 display dot. Use before displayBit().
  if(dat/10000 != 0){
    DigitalTube.displayBit(1, dat%100000/10000);  
    DigitalTube.displayBit(2, dat%10000/1000);
    DigitalTube.displayBit(3, dat%1000/100);
    DigitalTube.displayBit(4, dat%100/10);
    return;
  }
  if(dat%10000/1000 != 0){
    DigitalTube.clearBit(1); 
    DigitalTube.displayBit(2, dat%10000/1000); 
    DigitalTube.displayBit(3, dat%1000/100);
    DigitalTube.displayBit(4, dat%100/10);
    return;
  }
  if(dat%1000/100 != 0){
  DigitalTube.clearBit(1); 
  DigitalTube.clearBit(2);
  DigitalTube.displayBit(3, dat%1000/100);
  DigitalTube.displayBit(4, dat%100/10);  
  return;
}
  DigitalTube.clearBit(1); 
  DigitalTube.clearBit(2);
  DigitalTube.clearBit(3);
  DigitalTube.displayBit(4, dat%100/10);
}
//**********************************************************************************