# RFID RC522 Help Required

**URL:** <https://forum.arduino.cc/t/rfid-rc522-help-required/1126402>\
**Category:** General Guidance\
**Created:** [May 13, 2023, 3:53am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402 "2023-05-13T03:53:53Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![fireworksandelytraisbest](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@fireworksandelytraisbest](https://forum.arduino.cc/u/fireworksandelytraisbest)\
**Post date:** [May 13, 2023, 3:53am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402/1 "2023-05-13T03:53:53Z")

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Hello.  
i recently got a arduino uno board, and a rc522 rfid reader. i found out that i CANNOT write the card i got. this is because whenever i try to clone a card with the `MF_RC522` library, it does nothing. please help.  
thanks, elytraandfireworkisbest.  
😄

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**Author:** ![UKHeliBob](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/ukhelibob/32/215663_2.png) [@UKHeliBob](https://forum.arduino.cc/u/UKHeliBob)\
**Post date:** [May 13, 2023, 6:27am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402/2 "2023-05-13T06:27:56Z")

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Welcome to the forum

Please post a schematic of your project and your test sketch, using code tags when you post it

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**Author:** ![fireworksandelytraisbest](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@fireworksandelytraisbest](https://forum.arduino.cc/u/fireworksandelytraisbest)\
**Post date:** [May 14, 2023, 2:37am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402/3 "2023-05-14T02:37:12Z")

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my wiring is:  
RFID SDA \> Pin 4  
RFID RST \> Pin 3  
RFID SCK \> Pin 13  
RFID MOSI \> Pin 11  
RFID MISO \> Pin 12  
and Power + GND to 3.3v and GND

the code that i try to use is:

```arduino
/*
 * --------------------------------------------------------------------------------------------------------------------
 * Example to change UID of changeable MIFARE card.
 * --------------------------------------------------------------------------------------------------------------------
 * This is a MFRC522 library example; for further details and other examples see: https://github.com/miguelbalboa/rfid
 * 
 * This sample shows how to set the UID on a UID changeable MIFARE card.
 * 
 * @author Tom Clement
 * @license Released into the public domain.
 *
 * Typical pin layout used:
 * -----------------------------------------------------------------------------------------
 * MFRC522 Arduino Arduino Arduino Arduino Arduino
 * Reader/PCD Uno/101 Mega Nano v3 Leonardo/Micro Pro Micro
 * Signal Pin Pin Pin Pin Pin Pin
 * -----------------------------------------------------------------------------------------
 * RST/Reset RST 9 5 D9 RESET/ICSP-5 RST
 * SPI SS SDA(SS) 10 53 D10 10 10
 * SPI MOSI MOSI 11 / ICSP-4 51 D11 ICSP-4 16
 * SPI MISO MISO 12 / ICSP-1 50 D12 ICSP-1 14
 * SPI SCK SCK 13 / ICSP-3 52 D13 ICSP-3 15
 *
 * More pin layouts for other boards can be found here: https://github.com/miguelbalboa/rfid#pin-layout
 */

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

#define RST_PIN 9 // Configurable, see typical pin layout above
#define SS_PIN 10 // Configurable, see typical pin layout above

MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

/* Set your new UID here! */
#define NEW_UID {0xDE, 0xAD, 0xBE, 0xEF}

MFRC522::MIFARE_Key key;

void setup() {
  Serial.begin(9600); // Initialize serial communications with the PC
  while (!Serial); // Do nothing if no serial port is opened (added for Arduinos based on ATMEGA32U4)
  SPI.begin(); // Init SPI bus
  mfrc522.PCD_Init(); // Init MFRC522 card
  Serial.println(F("Warning: this example overwrites the UID of your UID changeable card, use with care!"));
  
  // Prepare key - all keys are set to FFFFFFFFFFFFh at chip delivery from the factory.
  for (byte i = 0; i < 6; i++) {
    key.keyByte[i] = 0xFF;
  }
}

// Setting the UID can be as simple as this:
//void loop() {
// byte newUid[] = NEW_UID;
// if ( mfrc522.MIFARE_SetUid(newUid, (byte)4, true) ) {
// Serial.println("Wrote new UID to card.");
// }
// delay(1000);
//}

// But of course this is a more proper approach
void loop() {
  
  // Reset the loop if no new card present on the sensor/reader. This saves the entire process when idle. And if present, select one.
  if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
    delay(50);
    return;
  }
  
  // Now a card is selected. The UID and SAK is in mfrc522.uid.
  
  // Dump UID
  Serial.print(F("Card UID:"));
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    Serial.print(mfrc522.uid.uidByte[i] < 0x10 ? " 0" : " ");
    Serial.print(mfrc522.uid.uidByte[i], HEX);
  } 
  Serial.println();

  // Dump PICC type
// MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
// Serial.print(F("PICC type: "));
// Serial.print(mfrc522.PICC_GetTypeName(piccType));
// Serial.print(F(" (SAK "));
// Serial.print(mfrc522.uid.sak);
// Serial.print(")\r\n");
// if ( piccType != MFRC522::PICC_TYPE_MIFARE_MINI 
// && piccType != MFRC522::PICC_TYPE_MIFARE_1K
// && piccType != MFRC522::PICC_TYPE_MIFARE_4K) {
// Serial.println(F("This sample only works with MIFARE Classic cards."));
// return;
// }
  
  // Set new UID
  byte newUid[] = NEW_UID;
  if ( mfrc522.MIFARE_SetUid(newUid, (byte)4, true) ) {
    Serial.println(F("Wrote new UID to card."));
  }
  
  // Halt PICC and re-select it so DumpToSerial doesn't get confused
  mfrc522.PICC_HaltA();
  if ( ! mfrc522.PICC_IsNewCardPresent() || ! mfrc522.PICC_ReadCardSerial() ) {
    return;
  }
  
  // Dump the new memory contents
  Serial.println(F("New UID and contents:"));
  mfrc522.PICC_DumpToSerial(&(mfrc522.uid));
  
  delay(2000);
}

```

Thanks.

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<div class="post-metadata">

**Author:** ![fireworksandelytraisbest](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@fireworksandelytraisbest](https://forum.arduino.cc/u/fireworksandelytraisbest)\
**Post date:** [May 14, 2023, 2:49am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402/4 "2023-05-14T02:49:50Z")

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hi @UKHeliBob, i solved the problem. the pin layout was incorrect. thanks for asking me to double check the code!!! 😄 but there is one more thing. It says that my rfid card is not a "changable" one. Can i change this "error"?

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**Author:** ![system](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/system/32/1140315_2.png) [@system](https://forum.arduino.cc/u/system)\
**Post date:** [November 10, 2023, 2:49am UTC](https://forum.arduino.cc/t/rfid-rc522-help-required/1126402/5 "2023-11-10T02:49:56Z")

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