2.35 RFID-RC522 Module


In this lesson, you will learn how to use RFID Module. RFID is the abbreviation of Radio Frequency Identification. Its working principle is to carry on the contactless data communication between the reader and the label to achieve the goal of identifying the target. The application of RFID is very extensive, currently the typical applications are animal chips, immobilizer, access control, parking control, production chain automation, material management and so on.

Fritzing Circuit

In this example, we insert the RFID into the breadboard. Get the 3.3V of RFID connected to 3.3V, GND to GND, RST to pin 2, SDA to pin 6, SCK to pin 5, MOSI to pin 4, MISO to pin 3 and IRQ to pin 7.


Schematic Diagram




  • You can open the file 2.35_RFID.ino under the path of sunfounder_vincent_kit_for_arduino\code\2.35_RFID directly.

  • Or copy this code into Arduino IDE 1/2.

  • Then Upload the Code to the board.

  • Please make sure you have added the library called rfid1, detailed tutorials refer to Add Libraries.

Uploaded the codes to the Mega2560 board, you can get your RFID card (secret key) close to the RFID Reader. The module will read the card information and then print it on the serial monitor.

Code Analysis

The functions of the module are included in the library rfid1.h.

#include <rfid1.h>

Library Functions:


Create a new instance of the rfid1 class that represents a particular RFID module attached to your Arduino .


Pin configuration.

  • IRQ_PIN,SCK_PIN,MOSI_PIN,MISO_PIN: the pins used for the SPI communication.

  • SDA_PIN: Synchronous data adapter.

  • RST_PIN: The pins used for reset.

void init()

Initialize the RFID.

uchar request(uchar reqMode, uchar *TagType);

Search card and read card type, and the function will return the current read status of RFID and return MI_OK if successed.

  • reqMode: Search methods. PICC_REQIDL is defined that 0x26 command bits (Search the cards that does not in the sleep mode in the antenna area).

  • *TagType: It is used to store card type, and its value can be 4byte (e.g. 0x0400).

char * readCardType(uchar *TagType)

This function decodes the four-digit hexadecimal number of *tagType into the specific card type and returns a string. If passed 0x0400, “MFOne-S50” will be returned.

uchar anticoll(uchar *serNum);

Prevent conflict, and read the card serial number. The function will return the current reading status of RFID. It returns MI_OK if successed.

  • *serNum: It is used to store the card serial number, and return the 4 bytes card serial number. The 5th byte is recheck byte(e.g. e.g. my magnetic card ID is 5AE4C955).

Phenomenon Picture