⊛ RFID-MFRC522 Is terrible and you shouldnt waste your time

Title states my opinion of this garbage RFID module.

Just like my previous project, This is part of the same project of finding the best style opensourced RFID reader/writer combo.

This module can read Mifare Ultralight, Classic 1K and Classic 4k cards…

I say the above on baited breath gritting through my teeth because yes, it “can” read these items, however the antenna design is poor, the coupling is poor, and the overall functionality of this module is poor. Range is piss-poor.

If you want your own little bundle of disapointment heres how you can make it:

RC522 – Arduino

SDA - D10
SCK - D13
MOSI - D11
MISO - D12
IRQ - Not connected
RST - D9
3.3V - 3.3V

OLED – Arduino

SCL - A5
SDA - A4
VCC - 5v

My Code is below:

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SPI.h>
#include <MFRC522.h>

#define OLED_RESET 4
Adafruit_SSD1306 display(OLED_RESET);

#define RST_PIN 9   // Define the RFID-RC522 reset pin
#define SS_PIN 10   // Define the RFID-RC522 SS pin
MFRC522 mfrc522(SS_PIN, RST_PIN);

void setup() {
  while (!Serial);

  // Initialize the OLED display
  display.begin(0x3C); // Set the I2C address to 0x3C
  display.display(); // Display start
  delay(2000); // Pause for 2 seconds

  // Initialize the RFID-RC522 reader

  // Clear the OLED display
  display.print("Hello Present Card");

  Serial.println("RFID-RC522 initialized.");

void loop() {
  // Look for new RFID cards
  if (mfrc522.PICC_IsNewCardPresent() && mfrc522.PICC_ReadCardSerial()) {
    // Clear the OLED display

    // Display the UID on the OLED
    display.print("Card UID:");
    display.setCursor(0, 24);

    for (byte i = 0; i < mfrc522.uid.size; i++) {
      if (i > 0) {
        display.print(" "); // Add a space between bytes
      display.print(mfrc522.uid.uidByte[i], HEX);

    // Identify and print the card type based on the SAK byte
    String cardType = "Unknown";

    if (mfrc522.uid.sak == 0x08) {
      cardType = "MIFARE Ultralight";
    } else if (mfrc522.uid.sak == 0x09) {
      cardType = "MIFARE Classic 1K";
    } else if (mfrc522.uid.sak == 0x18) {
      cardType = "MIFARE Classic 4K";
    } // Add more SAK values for different card types

    display.setCursor(0, 0);
    display.print("Card Type: ");

    // Update the OLED display with the UID and card type information

    // Display the UID and Card Type on the Serial Monitor
    Serial.println("A new card is present.");
    Serial.print("Card Type: ");
    Serial.print("UID Value: ");
    for (byte i = 0; i < mfrc522.uid.size; i++) {
      Serial.print(mfrc522.uid.uidByte[i], HEX);
      if (i < mfrc522.uid.size - 1) {
        Serial.print(" "); // Add a space between bytes

    // Halt reading new cards to prevent continuous reads

Dont bother, this is trash.

Case File on my Thingaverse account

We have a reviews section! @Pilgrimsmaster can massage this into a zero star review for you I’m sure haha

1 Like

Didn’t know if it was a review or a project or both


Only slightly late to this thread, but I recall on some other forum people replacing an inductor + cap or two on this and massively improving the range, I’ll see if I can dig out a link sometime. But yeah, a genuine PN532 module is way better


would love to see that thread if you can find it. I havent dismantled this unit yet as i have all the arduino’s i need for the next set of testing. But would be nice to see increased range on this.

This seems to be the most common RFID module that comes with most breadboard electronics kits.

I was working on building a door access control system with a raspberry pi zero. Yeah the read range on these are pretty poor. Is the PN532 better for read range? If not, can someone recommend a good reader?

Pn532 has excellent range and can seem to read a larger variety of chips. I have a similar project posted here with great results and an export of my code

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Found it!!!


As I had vaguely remembered, replacing two inductors can improve the range to read up to 70mm away with standard cards.

Hopefully this helps someone :slight_smile:

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