RFID RC522 reads the previous tag serial with different tag

Projects Programming
1

Hi everyone. I hope someone can help me.

I'm using a Mega with RC522, and this happens:

I use a tag, it reads the right serial (e.g. AA:BB:CC:DD). Then I use a second tag and sometimes it gives me the correct value (e.g. 00:11:22:33), but often it gives me the previous tag serial (AA:BB:CC:DD). After a few attempts, it finally gives me the right one (00:11:22:33).

I really can't find what's wrong and i'd be grateful if someone could shed some light.

Here's the code:

if (RC522.PICC_IsNewCardPresent())  {   
           RC522.PICC_ReadCardSerial();           
          String strID = "";
        for (byte i = 0; i < 4; i++) {
          strID +=
            (RC522.uid.uidByte[i] < 0x10 ? "0" : "") +
            String(RC522.uid.uidByte[i], HEX) +
            (i != 3 ? ":" : "");
        }
        String seriale = strID;

        if (seriale != "0"){

          for(h=0; h<=numerogiocatori -1;h++){
            
            if (seriale == seriali[h]) {
              lcd.clear();
              lcd.print("Saldo Gioc. ") ;
              lcd.print(h + 1) ;
              Serial.print("tag ID: ");
              Serial.print(seriale);
              Serial.print(" .    ");
              lcd.setCursor(0, 1);
              lcd.print(totaledenaro[h]) ;
              delay(1500);
              lcd.clear();
              lcd.print("Importo");  
              lcd.setCursor(0, 1);
            }
          }
        }

        }

Thanks to anyone willing to help!

2

Can the command PICC_HaltA(); help?