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6.5 Interfacing RFID

In this lesson, we’ll explore how to use Radio Frequency Identification (RFID) technology with the Raspberry Pi Pico 2. RFID allows for wireless communication between a reader and tags, which can be used for identification, authentication, and data storage.

What You’ll Need

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	LINK
Newton Lab Kit	450+	Newton Lab Kit

You can also buy them separately from the links below.

SN	COMPONENT	QUANTITY	LINK
1	Raspberry Pi Pico 2	1	BUY
2	Micro USB Cable	1
3	Breadboard	1	BUY
4	Jumper Wires	Several	BUY
5	MFRC522 Module	1	BUY

Understanding RFID

RFID technology uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information, which can be read from a distance without direct line-of-sight.

• RFID Reader (MFRC522): A device that emits radio waves to communicate with RFID tags.

• RFID Tag: A small object, such as a card or key fob, that contains a microchip and antenna. It can be passive (no battery) or active (battery-powered).

Circuit Diagram

Wiring Diagram

Writing the Code

We’ll write two separate scripts:

Note

Here you need to use the libraries in mfrc522 folder, please check if it has been uploaded to Pico, for a detailed tutorial refer to Upload the Libraries to Pico.

1. Writing Data to an RFID Tag:

   • SimpleMFRC522 class from the mfrc522 library simplifies interactions with the RFID reader.

   • The reader is initialized with the specified SPI pins.

   • Prompts the user to input data to write.

   • Instructs the user to place the tag near the reader.

   • Writes the data to the tag using reader.write(data).

   Note

   Open the 6.5_rfid_write.py file from newton-lab-kit/micropython or copy this code into Thonny, then click “Run Current Script” or simply press F5 to run it.

   from mfrc522 import SimpleMFRC522
   from machine import Pin, SPI
   
   # Initialize the RFID reader
   reader = SimpleMFRC522(spi_id=0, sck=18, mosi=19, miso=16, cs=17, rst=9)
   
   def write_to_tag():
       try:
           data = input("Enter data to write to the tag: ")
           print("Place your tag near the reader...")
           reader.write(data)
           print("Data written successfully!")
       finally:
           pass  # Cleanup actions if necessary
   
   write_to_tag()
   

   After running, the following occurs:

   • The program displays:

     Enter data to write to the tag:"
     

   • You input the text you want to write to the RFID tag and press Enter.

   • The program then shows:

     Place your tag near the reader...
     

   • You place the RFID tag near the reader module.

   • After successfully writing the data, it displays:

     Data written successfully!
     

2. Reading Data from an RFID Tag:

   • Instructs the user to place the tag near the reader.

   • Reads the tag’s ID and stored text using reader.read().

   • Prints out the tag’s ID and the data read from the tag.

   Note

   Open the 6.5_rfid_read.py file from newton-lab-kit/micropython or copy this code into Thonny, then click “Run Current Script” or simply press F5 to run it.

   from mfrc522 import SimpleMFRC522
   from machine import Pin, SPI
   
   # Initialize the RFID reader
   reader = SimpleMFRC522(spi_id=0, sck=18, mosi=19, miso=16, cs=17, rst=9)
   
   def read_from_tag():
       try:
           print("Place your tag near the reader...")
           id, text = reader.read()
           print("Tag ID: {}".format(id))
           print("Data: {}".format(text.strip()))
       finally:
           pass  # Cleanup actions if necessary
   
   read_from_tag()
   

   After running, the program prints the message “Place your tag near the reader…”. You need to place an RFID tag near the MFRC522 reader module, then program prints the retrieved information to the console. The output will look something like:

   Tag ID: 1234567890
   Data: Your stored message
   

Understanding the Code

• RFID Communication: The MFRC522 module communicates with the RFID tag using radio waves. When the tag is within range, the reader can read or write data to the tag’s memory.

• SPI Interface: The module communicates with the Pico via the SPI protocol, allowing for fast data transfer.

• Data Storage: RFID tags have limited storage capacity, suitable for storing small amounts of data like IDs or short text.

Applications

• Access Control Systems: Use RFID tags as keys to unlock doors or devices.

• Inventory Management: Track items in a warehouse or store by tagging them with RFID tags.

• Attendance Systems: Record attendance by scanning RFID tags assigned to individuals.

Experimenting Further

• Multiple Tags: Try writing different data to multiple tags and reading them back.

• Security Measures: Implement basic authentication to prevent unauthorized access.

• Data Formatting: Store structured data, such as JSON or CSV, for more complex applications.

Conclusion

In this lesson, you’ve learned how to interface an RFID reader with the Raspberry Pi Pico 2 to read and write data to RFID tags. This technology opens up possibilities for numerous applications in identification, tracking, and automation.