How can I add more RFID Tag's to this sketch ?

Projects General Guidance
1

Hello guys!

I just made this project for some home door unlock system.

https://create.arduino.cc/projecthub/Techinc1510/rfid-reader-with-lcd-1602-6cbb1e

How can I add more Tag's on this sketch ?

Thank you very much!

PS: It works very well but only with one tag.

//All Credit Technic 1510
//
//
//
//
#include <SPI.h>
#include <MFRC522.h>
#include <LiquidCrystal.h>
#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);   
LiquidCrystal lcd(6 , 7, 5, 4, 3, 2);

 
void setup() 
{
  
  SPI.begin();     
  mfrc522.PCD_Init();   
  lcd.begin(16, 2);
  lcd.print("Scan RFID Card");
  

}
void loop() 
{

  if ( ! mfrc522.PICC_IsNewCardPresent()) 
  {
    return;
  }

  if ( ! mfrc522.PICC_ReadCardSerial()) 
  {
    return;
  }

  lcd.clear();
  lcd.begin(16, 2);
  lcd.print("UID tag :");
  String content= "";
  byte letter;
  for (byte i = 0; i < mfrc522.uid.size; i++) 
  {
    lcd.setCursor(0, 1);
     lcd.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
     lcd.print(mfrc522.uid.uidByte[i], HEX);
     content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
     content.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
lcd.clear();
lcd.begin(16, 2);
 lcd.print("Your level is ");
 content.toUpperCase();
  if (content.substring(1) == "A4 F2 5A EC") //Plz change to your cards UID
  {
   lcd.setCursor(0,1);
    lcd.print("Access Granted ");

    delay(3000);
   lcd.clear();
    setup();
  }
 
 else   {
  lcd.setCursor(0, 1);
    lcd.print(" Access Denied");
    delay(3000);
    lcd.clear();
      setup();
      }
}
3

There is no need to repeatedly call lcd.begin() and setup().

Also, if you want this to run a long time, get rid of the String class and learn how to use C-strings instead.

//All Credit Technic 1510
//
//
//
//
#include <SPI.h>
#include <MFRC522.h>
#include <LiquidCrystal.h>
#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);
LiquidCrystal lcd(6 , 7, 5, 4, 3, 2);

void setup()
{
  SPI.begin();
  mfrc522.PCD_Init();
  lcd.begin(16, 2);
  lcd.print("Scan RFID Card");
}


void loop()
{
  if ( ! mfrc522.PICC_IsNewCardPresent())
  {
    return;
  }

  if ( ! mfrc522.PICC_ReadCardSerial())
  {
    return;
  }

  lcd.clear();
  //lcd.begin(16, 2);
  lcd.print("UID tag :");
  String content = "";
  byte letter;
  for (byte i = 0; i < mfrc522.uid.size; i++)
  {
    //lcd.setCursor(0, 1);
    lcd.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    lcd.print(mfrc522.uid.uidByte[i], HEX);
    content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
    content.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
  lcd.clear();
  //lcd.begin(16, 2);
  lcd.print("Your level is ");
  lcd.setCursor(0, 1);
  content.toUpperCase();
  if (content.substring(1) == "A4 F2 5A EC") //Plz change to your cards UID
  {
    lcd.print("Access Granted ");
  }
  else
  {
    lcd.print(" Access Denied");
  }
  delay(3000);
  lcd.clear();
  lcd.print("Scan RFID Card");
}