How to Write Data to RFID Card using RC522 RFID and Arduino

Revolutionizing Data Management: Unleashing the Potential of RC522 RFID and Arduino for RFID Card Writing

Radio Frequency Identification (RFID) technology has revolutionized data transfer and information storage. This article will delve into writing data onto RFID cards using the powerful combination of Arduino and the RC522 RFID module. But first, let’s understand the fundamentals of RFID.

What is RFID?

RFID, short for Radio Frequency Identification, uses electromagnetic waves to wirelessly transmit data or information. It comprises two primary components:

  1. RFID Transponder: This component functions as cards, tags, key fobs, or stickers, providing a unique identifier for various applications.
  2. RFID Transceiver: The transceiver acts as a reader/writer, enabling the reading or writing of data to and from the RFID transponder.

RC522 RFID Module and Arduino Integration

(image credit circuitdigest) RC522 RFID Reader

To facilitate a comprehensive understanding of the topic, we will explore the application of the RC522 RFID module alongside Arduino, a versatile and popular host controller. If you require additional information regarding RFID communication, the MFRC522 IC, or the RC522 RFID module, refer to our previously published article on Arduino RC522 RFID Module-based Access Control System.

Technological Advancements

In the rapidly evolving world of technology, numerous advancements have emerged since the publication of our previous article. Tech enthusiasts and experts have praised the seamless integration of the RC522 RFID module and Arduino, applauding its reliability and user-friendly nature.

The RC522 RFID module and Arduino provide an intuitive platform for writing data onto RFID cards. The article highlights the simplicity of the process, making it accessible even to those with limited technical expertise. 

RFID Specialist states, “Integrating the RC522 RFID module with Arduino for writing data onto MIFARE 1K RFID cards is a game-changer. The combination offers a cost-effective solution for storing custom data, such as student information or employee details. The user-friendly nature of Arduino and the reliability of the RC522 RFID module make it accessible to a wide range of users, from beginners to professionals. This technology opens up new possibilities for applications in access control systems, inventory management, and more.”

 Advancements in RFID Technology

As we look ahead, the future of RFID technology appears promising, with ongoing research and development aimed at enhancing its capabilities. Some notable advancements expected shortly include:

  1. Increased Storage Capacity: Researchers are working on improving the storage capacity of RFID cards, allowing for the storage of more extensive data sets and enabling more sophisticated applications.
  2. Enhanced Security Features: Security is a crucial aspect of RFID technology. Efforts are being made to develop advanced encryption algorithms and authentication protocols to ensure the integrity and confidentiality of data stored on RFID cards.
  3. Integration with IoT: RFID technology with the Internet of Things (IoT) is gaining momentum. This integration will enable seamless connectivity and communication between RFID devices, opening new avenues for smart applications and automation.

Using the RC522 RFID module with Arduino presents an efficient and accessible method for writing data onto MIFARE 1K RFID cards. This technology empowers individuals and organizations to store custom information securely and conveniently. As advancements in RFID technology continue to unfold, we can anticipate even more remarkable applications and innovations shortly.

Whether you are a student, an employee, or an enthusiast exploring the world of RFID, this comprehensive guide equips you with the knowledge to harness the power of Arduino and the RC522 RFID module. 

How to Write Data to RFID Cards Using RC522 RFID Module

This informative guide will walk you through writing data for RFID cards using the RC522 RFID module. RFID technology has become increasingly popular and utilized in various cutting-edge applications. By understanding how to leverage the capabilities of the RC522 RFID module, you can tap into the exciting world of contactless payments, automatic check-out systems, goods tracking in warehouses, and much more.

RFID Module Functionality

The RFID module operates through the interaction of antennas and integrated circuits (ICs). Firstly, an antenna in the RFID module emits high-frequency electromagnetic waves. Simultaneously, RFID tags, or transponders, equipped with antennas and ICs, receive these waves simultaneously.

Upon receiving the high-frequency waves, the RFID tags’ antennas charge the ICs within them. The ICs then scan the stored information and respond with a radio signal.

Now, what exactly are ICs? IC stands for an integrated circuit, a small electronic device containing various components and courses within a single unit. These ICs are vital in storing and processing data within RFID tags.

Applications of RFID Tags

RFID technology finds extensive applications across numerous industries. One notable implementation is the contactless payment system, enabling seamless transactions in supermarkets, banks, and offices. Additionally, RFID modules are instrumental in automating the check-out process in retail environments.

Furthermore, tracking goods in warehouses heavily relies on RFID technology, enhancing efficiency and inventory management. These are just a few examples of the diverse range of applications where RFID modules are being utilized.

By familiarizing yourself with the working principles and applications of the RC522 RFID module, you can unlock the full potential of this technology and explore innovative solutions across various domains.

The RC522 RFID Module

The RC522 RFID module has emerged as a cost-effective and versatile RFID reader module. Built around the MFRC522 RFID IC from NXP, this module offers extensive compatibility with a wide range of RFID tags. Let’s delve into the updated features and capabilities of the RC522 RFID module in 2023.

The RC522 RFID module boasts excellent compatibility with various RFID tags, including the popular ones mentioned below:

Image credit electronic hub
  1. MIFARE 1K: The RC522 RFID module seamlessly integrates with MIFARE 1K RFID cards, providing efficient data transfer and storage capabilities.
  2. MIFARE 4K: With its enhanced capabilities, the RC522 RFID module also supports MIFARE 4K RFID cards, offering a larger storage capacity for data-intensive applications.
  3. MIFARE Mini: This module extends its compatibility with MIFARE Mini RFID cards, enabling seamless integration with a broader range of RFID-enabled systems.
  4. ISO/IEC 14443 Protocol-based Cards and Tags: The RC522 RFID module adheres to the ISO/IEC 14443 protocol, ensuring compatibility with various cards and tags based on this industry standard.

Furthermore, the RC522 RFID module offers three types of serial communication options for seamless integration with microcontrollers:

  1. SPI (Serial Peripheral Interface): The SPI communication protocol facilitates high-speed data exchange between the RC522 RFID module and microcontrollers, ensuring efficient processing and reliable communication.
  2. UART (Universal Asynchronous Receiver-Transmitter): The UART communication option enables asynchronous serial communication, allowing straightforward integration with microcontrollers supporting this interface.
  3. I2C (Inter-Integrated Circuit): The I2C communication protocol provides a simple and efficient data transfer between the RC522 RFID module and microcontrollers, promoting seamless integration and ease of use.

Exploring the Memory Map of MIFARE 1K Tags

To fully comprehend the inner workings of MIFARE 1K tags, it is crucial to delve into the memory map of these tags and grasp the significance of each memory location. By understanding where memory is stored, reserved areas, and available storage space, you will be equipped with valuable knowledge for efficient data management.

To exemplify the process, let’s consider the scenario where the ‘Dumpinfo’ file is uploaded, and the Serial Monitor is opened for verification. Upon execution, the Arduino meticulously scans all the information and presents the relevant content about MIFARE 1K RFID tags on the serial screen.

The accompanying image clearly depicts the output derived from the ‘Dumpinfo’ file, as observed on the Serial Monitor. Let us explore this output in greater detail.

Image credit electronic hub

As we embark on this exploration of the memory map of MIFARE 1K tags, it is essential to recognize the significance of each memory location and comprehend the allocation of memory resources within these tags. This knowledge will prove invaluable for effectively managing and utilizing the available storage space, enabling seamless data storage and retrieval.

Decoding Serial Monitor Output

A wealth of information unfolds as we carefully analyze the Serial Monitor output. Starting with the version of the MFRC522 IC, the above image or screenshot provides us with invaluable insights:


In this result, the digit “9” signifies the utilization of the MFRC522 IC, while “2” indicates the adoption of the 2.0 software version. Subsequently, upon scanning an RFID card, crucial details such as the UID (Unique Identifier), SAK (Select Acknowledge), and RFID tag information become readily available.

In the provided image, the UID appears as ‘6C 08 88 17′, the SAK as ’08’, and the card type as MIFARE 1K. Typically, a standard MIFARE 1K RFID tag boasts a storage capacity of 1K byte. However, this capacity is divided into 16 sectors (numbered 0 to 15), with each sector further subdivided into four blocks. We can gain insights into the storage methodology employed through careful observation of the image.

Image credit electronic hub

Understanding the Memory Map of MIFARE 1K Tags

Before we proceed further, it’s important to note that the sector numbers provided here are for explanatory purposes, aiding our understanding of the memory layout.

So let’s get started:

Sector 0 =Blocks 0, 1, 2 and 3.
Sector 1 =Blocks 4, 5, 6 and 7.
Sector 2 =Blocks 7, 8, 9 ,10
Sector 3 =Blocks 11,12,13 ,14
Sector 4 =Blocks 15, 16,17, 18
Sector 5 =Blocks 19, 20, 21 ,22
Sector 6 =Blocks 23, 24 ,25, 26
Sector 7 =Blocks 27, 28 ,29 , 30
Sector 8 =Blocks 31, 32, 33,34
Sector 9 =Blocks 35 ,36 ,37 ,38

Each block possesses a storage capacity of 16 bytes. Therefore, the calculation is as follows:

16 (sectors) × 4 (blocks) × 16 (bytes) = 1024 (bytes) = 1K

Image credit electronic hub

Sector Reservations and Utilization

Block 0 of Sector 0 is typically reserved for storing essential processing data. This block consists of a 4-byte UID (Unique Identifier). It is primarily reserved for MIFARE 1K tags, MIFARE 4K tags, MIFARE Mini tags from NXP, and advanced tags like MIFARE Plus, MIFARE Ultralight, and MIFARE DESFIRE. The storage capacity for these tags’ UIDs is 7 bytes.

Image credit electronic hub

By decoding the Serial Monitor output and unraveling the mysteries of the memory map, we gain a deeper understanding of how data is organized and stored within MIFARE 1K tags.

Sector Trailers and Access Bits in MIFARE 1K RFID Tag

As we explore the intricacies of MIFARE 1K RFID tags, a question arises: what exactly is a Sector Trailer

In essence, each sector of the RFID tag reserves three blocks for storing user data. However, specific blocks within each industry, such as Block 3 in Sector 0 and Block 7 in Sector 1, are designated as Sector Trailers.

To provide a concise overview, there are a total of 16 sectors, with each sector housing a Sector Trailer. These Sector Trailers contain crucial data, including a mandatory 6-byte Key A, 4 bytes for Access Bits, and an optional 6-byte Key B (which can be omitted if not utilized, allowing for data storage).

Image credit electronic hub

It is important to note that all sectors are uniformly divided into three data blocks and one Sector Trailer. However, Sector 0 differs slightly from the others, as it is primarily used for data processing. Consequently, Sector 0 is divided into two data blocks, one Sector Trailer, and an additional 9-byte space reserved for user data, known as “Access Bits.”

Now, what exactly are Access Bits? For a comprehensive explanation, refer to the provided link. In brief, Access Bits are incorporated into the Sector Trailer and are responsible for analyzing the conditions of all blocks within a sector. They dictate the access conditions for various operations such as reading, writing, incrementing, decrementing, transferring, and restoring data. A storage space of 3 bits is needed to specify the Access Conditions for the three data blocks and the Sector Trailer.

Image credit electronic hub

After examining these details, it becomes evident that MIFARE 1K RFID tags can store up to 47 bytes of data. Now, let’s move forward and explore the process of writing data to RFID tags using Arduino and the RC522 RFID module.

Interface RFID with Arduino using RC522.

Based on our previous explanations, the MFRC522 IC supports three types of serial communication: UART, SPI, and I²C. The SPI interface offers the most common and efficient serial communication among these options.

The accompanying image illustrates the pinout of the RC522 RFID module; for optimal communication between Arduino and the RC522 module, the hardware SPI pins are utilized. The provided tables showcase the compatibility between Arduino and RC522 modules, aiding in the successful interfacing of these components.

By understanding the inner workings of Sector Trailers, Access Bits, and the interface between Arduino and the RC522 RFID module, you are well-equipped to delve into the exciting realm of writing data for RFID tags. Stay tuned for the next steps in this fascinating journey of exploration.

Writing Data onto MIFARE 1K RFID Cards

The MIFARE 1K RFID cards offer ample storage capacity, making them ideal for storing custom data such as student information or employee details. Following the steps outlined below, you can quickly write data onto these cards using the RC522 RFID module and Arduino.

Step 1: Gather the Necessary Components

To begin, ensure you have the following components:

  • Arduino board (such as Arduino Uno)
  • RC522 RFID module
  • MIFARE 1K RFID card
  • Jumper wires

Step 2: Set Up the Circuit

Connect the RC522 RFID module to the Arduino board using the jumper wires. Refer to the datasheets or product manuals for pin configurations and wiring instructions.

(image credit circuitdigest)

Step 3: Install Required Libraries

You need to install the appropriate libraries to enable communication between the RC522 RFID module and Arduino. Libraries like “MFRC522” are readily available for download from the Arduino Library Manager or trusted online sources.

image credit lastminuteengineers

Step 4: Upload the Sketch

Open the Arduino IDE and upload the RFID writing sketch to the board. The sketch should contain the code for initializing the RC522 RFID module and writing data onto the MIFARE 1K RFID card. Modify the code to suit your requirements, such as the data format and content.

image credit lastminuteengineers

Step 5: Test and Verify

Once the sketch is uploaded successfully, it’s time to test the system. Place the MIFARE 1K RFID card within the range of the RC522 RFID module. The module will detect the card, and the Arduino will write the specified data onto it. Verify the reported data by reading it back using the RC522 RFID module and Arduino.

Writing on RFID Cards

As we venture into writing data on RFID cards, it is essential to adhere to specific guidelines. When adding programs to blocks, ensuring that the data occupies a maximum of 16 bytes is crucial. This constraint ensures optimal utilization of storage capacity while accommodating any simple program.

Let’s explore the code snippet below, specifically designed for Arduino, which facilitates the seamless writing of data onto MIFARE 1K RFID tags. Feel free to copy and utilize it in your projects.

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

/*Using Hardware SPI of Arduino */
/*MOSI (11), MISO (12) and SCK (13) are fixed */
/*You can configure SS and RST Pins*/
#define SS_PIN 10  /* Slave Select Pin */
#define RST_PIN 7  /* Reset Pin */

/* Create an instance of MFRC522 */
MFRC522 mfrc522(SS_PIN, RST_PIN);
/* Create an instance of MIFARE_Key */
MFRC522::MIFARE_Key key;          

/* Set the block to which we want to write data */
/* Be aware of Sector Trailer Blocks */
int blockNum = 2;  
/* Create an array of 16 Bytes and fill it with data */
/* This is the actual data which is going to be written into the card */
byte blockData [16] = {"Electronics-Hub-"};

/* Create another array to read data from Block */
/* Legthn of buffer should be 2 Bytes more than the size of Block (16 Bytes) */
byte bufferLen = 18;
byte readBlockData[18];

MFRC522::StatusCode status;

void setup() 
  /* Initialize serial communications with the PC */
  /* Initialize SPI bus */
  /* Initialize MFRC522 Module */
  Serial.println("Scan a MIFARE 1K Tag to write data...");

void loop()
  /* Prepare the ksy for authentication */
  /* All keys are set to FFFFFFFFFFFFh at chip delivery from the factory */
  for (byte i = 0; i < 6; i++)
    key.keyByte[i] = 0xFF;
  /* Look for new cards */
  /* Reset the loop if no new card is present on RC522 Reader */
  if ( ! mfrc522.PICC_IsNewCardPresent())
  /* Select one of the cards */
  if ( ! mfrc522.PICC_ReadCardSerial()) 
  Serial.println("**Card Detected**");
  /* Print UID of the Card */
  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);
  /* Print type of card (for example, MIFARE 1K) */
  Serial.print(F("PICC type: "));
  MFRC522::PICC_Type piccType = mfrc522.PICC_GetType(mfrc522.uid.sak);
   /* Call 'WriteDataToBlock' function, which will write data to the block */
   Serial.println("Writing to Data Block...");
   WriteDataToBlock(blockNum, blockData);
   /* Read data from the same block */
   Serial.println("Reading from Data Block...");
   ReadDataFromBlock(blockNum, readBlockData);
   /* If you want to print the full memory dump, uncomment the next line */
   /* Print the data read from block */
   Serial.print("Data in Block:");
   Serial.print(" --> ");
   for (int j=0 ; j<16 ; j++)

void WriteDataToBlock(int blockNum, byte blockData[]) 
  /* Authenticating the desired data block for write access using Key A */
  status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, blockNum, &key, &(mfrc522.uid));
  if (status != MFRC522::STATUS_OK)
    Serial.print("Authentication failed for Write: ");
    Serial.println("Authentication success");

  /* Write data to the block */
  status = mfrc522.MIFARE_Write(blockNum, blockData, 16);
  if (status != MFRC522::STATUS_OK)
    Serial.print("Writing to Block failed: ");
    Serial.println("Data was written into Block successfully");

void ReadDataFromBlock(int blockNum, byte readBlockData[]) 
  /* Authenticating the desired data block for Read access using Key A */
  byte status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, blockNum, &key, &(mfrc522.uid));

  if (status != MFRC522::STATUS_OK)
     Serial.print("Authentication failed for Read: ");
    Serial.println("Authentication success");

  /* Reading data from the Block */
  status = mfrc522.MIFARE_Read(blockNum, readBlockData, &bufferLen);
  if (status != MFRC522::STATUS_OK)
    Serial.print("Reading failed: ");
    Serial.println("Block was read successfully");  

Exploring the Cutting-Edge Applications of RFID Cards in 2023

In 2023, RFID cards are transforming industries with their cutting-edge applications, including:

  1. Contactless Payment Systems: RFID cards revolutionize payment processes by enabling contactless transactions through near-field communication (NFC) technology. This innovation enhances convenience, speeds up transactions, and simplifies payment experiences for consumers and businesses.
  2. Inventory Management: RFID technology incorporated into supply chains allows real-time tracking and monitoring of products. RFID cards store unique identification codes, enabling businesses to optimize stock management, minimize losses, and improve inventory accuracy and efficiency.
  3. Supply Chain Optimization: By utilizing RFID cards, businesses can achieve seamless tracking and tracing of goods throughout the supply chain. This technology enhances routing optimization, improves delivery accuracy, and streamlines supply chain operations.
  4. Access Control: RFID cards have replaced traditional key-based access control systems, offering secure and convenient solutions. Organizations implement RFID-based access control systems, enhancing security, eliminating the need for physical keys, and simplifying authorized access management.

These applications highlight how RFID cards will reshape industries in 2023, driving efficiency, security, seamless experiences in contactless payments, inventory management, supply chain optimization, and access control.

Concluding Remarks on Writing Data to RFID Cards

In this comprehensive guide, we have taken you through the process of writing data to RFID cards using the state-of-the-art RC522 RFID Reader/Writer Module in conjunction with the Arduino UNO. By following our simple demonstration, you have gained valuable insights into the memory layout of MIFARE Classic 1K RFID tags, discovered the optimal memory locations for data storage, and even successfully written random text to an RFID card.

As we navigate the technological landscape of 2023, the ability to harness the potential of RFID technology has become increasingly vital. With the RC522 RFID module and Arduino UNO as your trusty allies, you have now acquired the knowledge and skills to write and store data on RFID cards effortlessly.

The memory layout of MIFARE Classic 1K RFID tags has been deciphered, granting you a deeper understanding of the memory locations best suited for data storage. With this knowledge, you can confidently embark on various applications requiring efficient data management.

Throughout this learning journey, we have emphasized simplicity and ease of implementation, ensuring that even newcomers to RFID technology can engage and explore its immense possibilities. By writing random text to an RFID card, you have witnessed firsthand the seamless integration of RC522 RFID technology with the Arduino UNO, enabling you to unleash your creativity and leverage this powerful combination to transform ideas into reality.

As we conclude this guide, we encourage you to continue your RFID exploration, harnessing the advancements of 2023 and beyond. Stay tuned for more updates, insights, and practical tutorials that will propel your understanding and proficiency in the world of RFID technology.

Remember, the power to write data to RFID cards lies in your hands. Embrace the possibilities, innovate confidently, and unlock this remarkable technology’s full potential.

fatima khan
fatima khan
A brand new writer in the fields, Fatima has been taken under my electric spark's RGB- rich and ensures she doesn't engage in excessive snark on the website. It's unclear what command and Conquer are; however, she can talk for hours about the odd rhythm games, hardware, product reviews, and MMOs that were popular in the 2000s. Fatima has been creating various announcements, previews, and other content while here, but particularly enjoys writing regarding Products' latest news in the market she's currently addicted to. She is likely talking to an additional blogger with her current obsession right now.