So I have an Arduino Uno and an MFRC-522 reader, using a breadboard I've wired it up according to the example sketch which is the mfrc522 DumpInfo sketch.

/*Typical pin layout used:
 * 
 *             MFRC522      Arduino 
 *             Reader/PCD   Uno/101
 * Signal      Pin          Pin     
 * -------------------------------
 * RST/Reset   RST          9          
 * SPI SS      SDA(SS)      10         
 * SPI MOSI    MOSI         11 / ICSP-4
 * SPI MISO    MISO         12 / ICSP-1
 * SPI SCK     SCK          13 / ICSP-3
 */

I've checked the wiring hundreds of times. The console shows Firmware Version: 0x92 = v2.0 Scan PICC to see UID, SAK, type, and data blocks...

but getting a card near the chip, will not scan or dump any info no other information appears on the serial monitor.

I've tried with mifare classic 1k cards a Nexus 6 and a Samsung Galaxy S7

Edit: Everything

    /*
    * ------------------------------------------------------------------------------------------------------------------
    * Example sketch/program showing how to read data from a PICC to serial.
    * --------------------------------------------------------------------------------------------------------------------
    * This is a MFRC522 library example; for further details and other examples see: https://github.com/miguelbalboa/rfid
    * 
    * Example sketch/program showing how to read data from a PICC (that is: a RFID Tag or Card) using a MFRC522 based RFID
    * Reader on the Arduino SPI interface.
    * 
    * When the Arduino and the MFRC522 module are connected (see the pin layout below), load this sketch into Arduino IDE
    * then verify/compile and upload it. To see the output: use Tools, Serial Monitor of the IDE (hit Ctrl+Shft+M). When
    * you present a PICC (that is: a RFID Tag or Card) at reading distance of the MFRC522 Reader/PCD, the serial output
    * will show the ID/UID, type and any data blocks it can read. Note: you may see "Timeout in communication" messages
    * when removing the PICC from reading distance too early.
    * 
    * If your reader supports it, this sketch/program will read all the PICCs presented (that is: multiple tag reading).
 * So if you stack two or more PICCs on top of each other and present them to the reader, it will first output all
 * details of the first and then the next PICC. Note that this may take some time as all data blocks are dumped, so
 * keep the PICCs at reading distance until complete.
 * 
 * @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
 */

#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

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
    mfrc522.PCD_DumpVersionToSerial();  // Show details of PCD - MFRC522 Card Reader details
    Serial.println(F("Scan PICC to see UID, SAK, type, and data blocks..."));
}

void loop() {
    // Look for new cards
    if ( ! mfrc522.PICC_IsNewCardPresent()) {
        return;
    }

    // Select one of the cards
    if ( ! mfrc522.PICC_ReadCardSerial()) {
        return;
    }

    // Dump debug info about the card; PICC_HaltA() is automatically called
    mfrc522.PICC_DumpToSerial(&(mfrc522.uid));
}

datasheet Nxp website /documents/data_sheet/MFRC522.pdf

When arduino starts and nothing changes when card is tapped

bumped to the homepage by Community yesterday

This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

  • Phones mosly use NFC which is at a higher freaquency then RFID. Are you sure they are even compatible? – Dat Ha Dec 31 '16 at 20:23
  • Pretty positive, But I also used many MiFare Classic cards which this reader is explicitly stated to be compatible with. with absolutely no results – Greeley Dec 31 '16 at 20:25
  • Can you post the whole post please? – Dat Ha Dec 31 '16 at 21:05
  • Edited main post – Greeley Dec 31 '16 at 21:23
  • Have you read MFRC522.h? It seems the 1K tags have a specific type of authentication. Also, be sure that the device has adequate power, during transmit it may suddenly use a lot more power. You may ultimately try another reader or card, to exclude any possible hardware defects in the antenna circuitry. – Paul Apr 1 '17 at 7:40

Maybe you need a function TO PRINT THE READINGS!!!

This is the loop and a function to print it:

void loop() {
  if ( ! rfid.PICC_IsNewCardPresent())
    return;
  if ( ! rfid.PICC_ReadCardSerial())
    return;

    for (byte i = 0; i < 4; i++) {
      nuidPICC[i] = rfid.uid.uidByte[i];
    }

    Serial.println(F("The NUID tag is:"));
    Serial.print(F("In hex: "));
    printHex(rfid.uid.uidByte, rfid.uid.size);

  rfid.PICC_HaltA();
  rfid.PCD_StopCrypto1();
}

void printHex(byte *buffer, byte bufferSize) {
  for (byte i = 0; i < bufferSize; i++) {
    Serial.print(buffer[i] < 0x10 ? " 0" : " ");
    Serial.print(buffer[i], HEX);
  }

}
  • 1
    mfrc522.PICC_DumpToSerial(&(mfrc522.uid)); Already prints to serial. It's almost like I actually know what I'm doing as far as code goes. in fact I already have my whole project written for this card. it just seems to not actually read anything. – Greeley Dec 31 '16 at 22:42

your breadboard can be buggy. In addition, are you connected VCC to 3V or 5V?
As I remember, you need to connect it to 3V.

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

void setup() {
  Serial.begin(9600);
  SPI.begin();
  RFID.PCD_Init();      // MFRC522
}
#define SS_PIN 10
#define RST_PIN 9

MFRC522 RFID(SS_PIN, RST_PIN);

void loop() {
  if (!RFID.PICC_IsNewCardPresent() || !RFID.PICC_ReadCardSerial())
    return;

  String buffer;
  for (byte byte = 0 ; byte < RFID.uid.size ; byte++)
    buffer += String(RFID.uid.uidByte[byte] < 0x10 ? " 0" : " ") + String(RFID.uid.uidByte[byte], HEX);
  Serial.println("NUID: " + buffer);

  RFID.PICC_HaltA();
  RFID.PCD_StopCrypto1();
}

I had a similar problem. I used I2C to check if the board can see the reader. If I2C Bus doesn't detect your reader, then one of your soldering must be faulty... check with a meter and carefully re-solder the erring pin.

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