Lesson 2.2.7 MFRC522 RFID Module

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Introduction

Radio Frequency Identification (RFID) refers to technologies that use wireless communication between an object (or tag) and interrogating device (or reader) to automatically track and identify such objects.

Some of the most common applications for this technology include retail supply chains, military supply chains, automated payment methods, baggage tracking and management, document tracking and pharmaceutical management, to name a few.

In this project, we will use RFID for reading and writing.

Components

Principle

RFID

Radio Frequency Identification (RFID) refers to technologies that involve using wireless communication between an object (or tag) and an interrogating device (or reader) to automatically track and identify such objects. The tag transmission range is limited to several meters from the reader. A clear line of sight between the reader and tag is not necessarily required.

Most tags contain at least one integrated circuit (IC) and an antenna. The microchip stores information and is responsible for managing the radio frequency (RF) communication with the reader. Passive tags do not have an independent energy source and depend on an external electromagnetic signal, provided by the reader, to power their operations. Active tags contain an independent energy source, such as a battery. Thus, they may have increased processing, transmission capabilities and range.

MFRC522

MFRC522 is a kind of integrated read and write card chip. It is commonly used in the radio at 13.56MHz. Launched by the NXP Company, it is a low-voltage, low-cost, and small-sized non-contact card chip, a best choice of intelligent instrument and portable handheld device.

The MF RC522 uses advanced modulation and demodulation concept which fully presented in all types of 13.56MHz passive contactless communication methods and protocols. In addition, it supports rapid CRYPTO1 encryption algorithm to verify MIFARE products. MFRC522 also supports MIFARE series of high-speed non-contact communication, with a two-way data transmission rate up to 424kbit/s. As a new member of the 13.56MHz highly integrated reader card series, MF RC522 is much similar to the existing MF RC500 and MF RC530 but there also exists great differences. It communicates with the host machine via the serial manner which needs less wiring. You can choose between SPI, I2C and serial UART mode (similar to RS232), which helps reduce the connection, save PCB board space (smaller size), and reduce cost.

Schematic Diagram

T-Board Name	physical	wiringPi	BCM
SPICE0	Pin 24	10	8
SPISCLK	Pin 23	14	11
SPIMOSI	Pin 19	12	10
SPIMISO	Pin 21	13	9
GPIO25	Pin 22	6	25

Experimental Procedures

Step 1: Build the circuit.

Step 2: Set up SPI (refer to Appendix for more details. If you have set SPI, skip this step.)

For C Language Users

Step 3: Go to the folder of the code.

    cd /home/pi/davinci-kit-for-raspberry-pi/c/2.2.7/

Step 4: Compile the code.

make read
make write

Step 4: Compile the code.

Note: There are two examples for you to read or write the card ID, and you can choose one of them according to your need.

Step 5: Run the executable file.

sudo ./read
sudo ./write

Code Explanation

InitRc522();

This function is used to initialize the RFID RC522 module.

uint8_t read_card_data();

This function is used to read the data of the card, and if the read is successful, it will return “1”.

uint8_t write_card_data(uint8_t *data);

This function is used to write the data of card and returns “1” if the write is successful. *data is the information that will be written to the card.

For Python Language Users

Step 3: Go to the folder of the code.

    cd /home/pi/davinci-kit-for-raspberry-pi/python/2.2.7

Step 4: Run the executable file.

sudo python3 2.2.7_read.py
sudo python3 2.2.7_write.py

Note: There are two examples for you to read or write the card ID, and you can choose one of them according to your need.

Code Explanation

RC522()

Instantiate rc522 class.

RC522.Pcd_start()

Initialize RFID

RC522.read_card_data(addr)

This function is used to read the card data. If the reading is successful, it will return “1”. addr is the address of the card.

RC522.write_card_data(addr, data)

This function is used to write card data, and if the write is successful, there will return “1”. addr is the address of the card and data is the information to be written to the card.

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