Connect Multiple I2C Devices to Arduino Using I2C Multiplexer TCA9548A

/*
  Made on 18 may 2021
  By Amirmohammad Shojaei
  
Home

  
*/
#include <Wire.h>

#include "SparkFunHTU21D.h"    //add HTU21D Library 
HTU21D myHumidity;

#include "Adafruit_Si7021.h"     //add GY-21 si7021 Library 
Adafruit_Si7021 sensor = Adafruit_Si7021();

#include "DFRobot_SHT20.h"       //add SHT20 Library 
DFRobot_SHT20 sht20;

#include <Adafruit_SSD1306.h>    //add SSD1306 OLED Library 
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

void TCA9548A(uint8_t bus) //function of TCA9548A
{
  Wire.beginTransmission(0x70);  // TCA9548A address is 0x70
  Wire.write(1 << bus);          // send byte to select bus
  Wire.endTransmission();
}

void setup()
{
  Serial.begin(9600);
  Wire.begin();
  delay(100);

  TCA9548A(2);
  myHumidity.begin();        //Initialize HTU21D Sensor

  TCA9548A(1);
  sht20.initSHT20();                         // Initialize SHT20 Sensor
  delay(100);
  sht20.checkSHT20();                        // Check SHT20 Sensor

  display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Initialize OLED

}

String T_SHT20;
String T_HTU21D;
String T_GY21;

void loop() {
  
  TCA9548A(1);
  float T_SHT20_S = sht20.readTemperature();   //Temperature of SHT20 Sensor 
  T_SHT20= String(T_SHT20_S);             //remmove one Decimal
  T_SHT20.remove(4,1);

  TCA9548A(2);
  float T_HTU21D_S = myHumidity.readTemperature();   //Temperature of HTU21D Sensor 
  T_HTU21D= String(T_HTU21D_S);          //remmove one Decimal
  T_HTU21D.remove(4,1);
  
  TCA9548A(7);
  float T_GY21_S = sensor.readTemperature();        //Temperature of GY21 Sensor 
  T_GY21= String(T_GY21_S);            //remmove one Decimal
  T_GY21.remove(4,1);
  
  Serial.print("T-SHT20: ");
  Serial.print(T_SHT20);      //print value of T-SHT20 on Serial Monitor
  Serial.print("C");

  Serial.print("   T-HTU21D: ");
  Serial.print(T_HTU21D);         //print value of T-HTU21D on Serial Monitor
  Serial.print("C");

  Serial.print("   T-GY21: ");
  Serial.print(T_GY21);           //print value of T-GY21 on Serial Monitor
  Serial.println("C");


  display.clearDisplay();
  display.setTextSize(2);      
  display.setTextColor(SSD1306_WHITE); // Draw Yellow text
  display.setCursor(1, 1);     // Start point
  display.print("T1: ");
  display.print(T_SHT20);
  display.println(" C");
  

  display.setTextSize(2);      // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE); // Draw Blue text
  display.setCursor(1, 22);     // Start point
  display.print("T2: ");
  display.print(T_HTU21D);
  display.println(" C");


  display.setTextSize(2);      
  display.setTextColor(SSD1306_WHITE); // Draw Blue text
  display.setCursor(1, 45);     // Start point
  display.print("T3: ");
  display.print(T_GY21);
  display.println(" C");
  display.display();
  
  delay(1000);
}