MFRC522: Firmware Unknown Can someone help me what is the meaning of this sketch? It always outputs in the serial monitor:

Firmware Version: 0x1C = (unknown)
Scan PICC to see UID, SAK, type, and data blocks...


This is the code of the MFRC522 library I use:

#include &lt;SPI.h&gt;
#include &lt;MFRC522.h&gt;

constexpr uint8_t RST_PIN = 9;          // Configurable, see typical pin layout above
constexpr uint8_t 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(&amp;(mfrc522.uid));
}
The mention of unknown in the output line:

Firmware Version: 0x1C = (unknown)


isn't a good sign.

Run the firmware_check example to verify that first, before trying to run other code.

The unknown is output by line 1302 of MFRC522.cpp:

    default:   Serial.println(F(" = (unknown)"));


The firmware_check example states on line 49:

  Serial.println(F("Only known versions supported"));


So, your hardware (i.e. the reader) may not be supported. 

The only thing I can suggest is try another reader. Also, read the README, there maybe some thing there, or contact the author and/or raise an issue to see if you can get support for your version of the firmware (0x1C) added.