Trying to scan 2 or 1 card to allow access and any other card denies access

Projects Programming
1

Is there anyway to make the code less complicated?

#include <SPI.h>
#include <MFRC522.h>
 
#define SS_PIN 10
#define RST_PIN 9
MFRC522 mfrc522(SS_PIN, RST_PIN);   // Create MFRC522 instance.
 
void setup() 
{
  Serial.begin(9600);   // Initiate a serial communication
  SPI.begin();      // Initiate  SPI bus
  mfrc522.PCD_Init();   // Initiate MFRC522
  Serial.println("Please present card to the reader...");
  Serial.println();

}
void loop() 
{
  // Look for new cards
  if ( ! mfrc522.PICC_IsNewCardPresent()) 
  {
    return;
  }
  // Select one of the cards
  if ( ! mfrc522.PICC_ReadCardSerial()) 
  {
    return;
  }
  //Show UID on serial monitor
  Serial.print("UID tag :");
  String content= "";
  byte letter;
  for (byte i = 0; i < mfrc522.uid.size; i++) 
  {
     Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
     Serial.print(mfrc522.uid.uidByte[i], HEX);
     content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
     content.concat(String(mfrc522.uid.uidByte[i], HEX));
  }
  Serial.println();
  Serial.print("Message : ");
  content.toUpperCase();
  if (content.substring(1) == "1A 80 FD DA"||"DB 93 46 E0") 
  {
    Serial.println("Please scan other card for access");
    delay(3000);
     if ( ! mfrc522.PICC_IsNewCardPresent()) 
     {
      Serial.println("Try again");
      return;
     }
     if ( ! mfrc522.PICC_ReadCardSerial())
     {
      return;
     }
      Serial.print("UID tag :");
      String content= "";
      byte letter;
      for (byte i = 0; i < mfrc522.uid.size; i++) 
      {
        Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
        Serial.print(mfrc522.uid.uidByte[i], HEX);
        content.concat(String(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " "));
        content.concat(String(mfrc522.uid.uidByte[i], HEX));
      }
      Serial.println();
      Serial.print("Message : ");
      content.toUpperCase();
      if (content.substring(1) == "DB 93 46 E0")
      {
        Serial.println("Access granted");
        delay(3000);
      }
      else
      {
        Serial.println(" Access denied");
        delay(3000);
      }
    Serial.println();
    delay(3000);
  }
}
2

Welcome

Yes, don't use String :slight_smile:

The card id is a 4-bytes number, so if you combine those bytes, then you can easily compare the card id to a number

And this is wrong

if (content.substring(1) == "1A 80 FD DA"||"DB 93 46 E0")

You can't do multiple comparisons like that

3

C++ isn't that close to English. You have to write this as something like:

  if (content.substring(1) == "1A 80 FD DA"
    || content.substring(1) == "DB 93 46 E0") 
  {
5

Thanks for the welcome
I am new to coding and do not know much.
Do you have a suggestion for not using string?
Could you provide an example code?

6

Post your new, changed, code. Without it, we can't help you more.

7

Whoops sorry for the confusion, I simply forgot to compile and upload my new code.
Everything is working as it seems now. Thanks

8

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