gistfile1.txt

#include <SPI.h>
#include <MFRC522.h>

#define SS_PIN 10
#define RST_PIN 9


MFRC522 mfrc522(SS_PIN, RST_PIN); 



char st[20];

void setup() 
{
  
  Serial.begin(9600);
  
  SPI.begin();
  
  mfrc522.PCD_Init(); 
  

}

void loop() 
{
  if ( ! mfrc522.PICC_IsNewCardPresent()) 
  {
    return;
  }
  if ( ! mfrc522.PICC_ReadCardSerial()) 
  {
    return;
  }
  // Muestra el UID de la tag
  
  String conteudo= "";
  byte letra;
  for (byte i = 0; i < mfrc522.uid.size; i++) 
  {
    
     conteudo.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
     conteudo.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
  
  conteudo.toUpperCase();
  
    if (conteudo.substring(1) == "4D AF 90 55")
  {
    
    Serial.print('A');
   }
    
  
  if (conteudo.substring(1) == "11 90 D0 0E")
  
    {
      Serial.print('B');
    }
  
  delay(1000);
}