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7.8 Building an RFID Music Player

In this project, we’ll create an RFID Music Player using the Raspberry Pi Pico 2, an MFRC522 RFID reader, a passive buzzer, and WS2812 RGB LEDs. By writing musical notes to RFID tags, we’ll read them back and have the Pico play the corresponding melody while displaying colorful LED effects. This project combines RFID technology with music generation, allowing you to store and share melodies on RFID cards or key fobs.

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	Transistor	1(S8050)	BUY
6	Resistor	1(1KΩ)	BUY
7	Passive Buzzer	1	BUY
8	MFRC522 Module	1	BUY
9	WS2812 RGB 8 LEDs Strip	1	BUY

Understanding the Components

• MFRC522 RFID Reader Module: A low-cost RFID reader that communicates over SPI. It can read and write data to RFID tags operating at 13.56 MHz.

• RFID Tags/Key Fobs: Passive devices that can store small amounts of data. We’ll write musical notes to these tags.

• Passive Buzzer: An electronic component that can produce sound when driven with a PWM signal. We’ll use it to play musical notes.

• WS2812 RGB LEDs: Also known as NeoPixels, these LEDs can display a wide range of colors and can be individually controlled over a single data line.

Circuit Diagram

Wiring Diagram

Writing the Code

We’ll write two scripts:

• 6.5_rfid_write.py: To store the musical notes on the RFID tag.

• 7.8_rfid_music_player.py: To read the stored notes and play the melody.

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. 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
   
   write_to_tag()
   

2. After running, type EEFGGFEDCCDEEDD EEFGGFEDCCDEDCC in the shell, then bring the RFID tag near the reader to store a score of “Ode to Joy”. Wait for the confirmation message: “Data written successfully!”

3. Open the 7.8_rfid_music_player.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
   import machine
   import time
   from ws2812 import WS2812
   import urandom
   
   # WS2812 LED setup
   # Initialize an 8-LED WS2812 strip on pin 0
   ws = WS2812(machine.Pin(0), 8)
   
   # MFRC522 RFID reader setup
   # Initialize the RFID reader using SPI on specific pins
   reader = SimpleMFRC522(spi_id=0, sck=18, miso=16, mosi=19, cs=17, rst=9)
   
   # Buzzer note frequencies (in Hertz)
   NOTE_C4 = 262
   NOTE_D4 = 294
   NOTE_E4 = 330
   NOTE_F4 = 349
   NOTE_G4 = 392
   NOTE_A4 = 440
   NOTE_B4 = 494
   NOTE_C5 = 523
   
   # Initialize PWM for buzzer on pin 15
   buzzer = machine.PWM(machine.Pin(15))
   
   # List of note frequencies corresponding to musical notes
   note = [NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4, NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5]
   
   # Function to play a tone on the buzzer with a specified frequency and duration
   def tone(pin, frequency, duration):
    pin.freq(frequency)  # Set the buzzer frequency
    pin.duty_u16(30000)  # Set duty cycle to 50% (approx)
    time.sleep_ms(duration)  # Play the tone for the specified duration
    pin.duty_u16(0)  # Stop the tone by setting duty cycle to 0
   
   # Function to light up a WS2812 LED at a specific index with a random color
   def lumi(index):
    for i in range(8):
        ws[i] = 0x000000  # Turn off all LEDs
    ws[index] = int(urandom.uniform(0, 0xFFFFFF))  # Set a random color for the LED at the given index
    ws.write()  # Write the color data to the WS2812 LEDs
   
   # Encode musical notes text into indices and play the corresponding notes
   words = ["C", "D", "E", "F", "G", "A", "B", "N"]  # Mapping of musical notes to text characters
   def take_text(text):
    string = text.replace(' ', '').upper()  # Remove spaces and convert the text to uppercase
    while len(string) > 0:
        index = words.index(string[0])  # Find the index of the first note in the string
        tone(buzzer, note[index], 250)  # Play the corresponding note on the buzzer for 250 ms
        lumi(index)  # Light up the LED corresponding to the note
        string = string[1:]  # Move to the next character in the string
   
   # Function to read from the RFID card and play the stored score
   def read():
    print("Reading...Please place the card...")
    id, text = reader.read()  # Read the RFID card (ID and stored text)
    print("ID: %s\nText: %s" % (id, text))  # Print the ID and text
    take_text(text)  # Play the score from the text stored on the card
   
   # Start reading from the RFID card and play the corresponding score
   read()
   

4. After running, the console will display: “Place your tag near the reader…”.

   Place the RFID Tag Near the Reader:

   • The Pico reads the data from the tag.

   • The console displays the tag ID and text.

   • The buzzer plays the melody corresponding to the notes stored on the tag.

   • The WS2812 LEDs light up with effects synchronized to the music.

Understanding the Code

• RFID Interaction:

  • The SimpleMFRC522 class simplifies reading and writing to RFID tags.

  • Writing Data: In write_to_tag(), user input is written to the tag.

  • Reading Data: In read_and_play(), data is read from the tag when it’s near the reader.

• Music Playback:

  • Notes Dictionary: Maps note characters to frequencies.

  • Parsing Notes: The text from the RFID tag is cleaned and iterated character by character.

  • Playing Notes: For each character, the corresponding frequency is played on the buzzer.

• LED Effects:

  • WS2812 Control: The ws object controls the RGB LEDs.

  • Lighting LEDs: For each note played, an LED lights up with a random color.

• Timing:

  • Note Duration: Each note is played for 300 milliseconds.

  • Pause Between Notes: A short pause of 100 milliseconds between notes.

Experimenting Further

• Create Your Own Melodies:

  • Write different musical notes to RFID tags.

  • Use notes C, D, E, F, G, A, B, and N (for rest).

  • Share your musical RFID tags with friends.

• Extend Note Range:

  • Add more octaves by defining additional frequencies.

  • Update the notes dictionary accordingly.

• Visual Enhancements:

  • Modify the light_led function to create different LED patterns.

  • Synchronize LED effects more closely with the music.

• Multiple Tags for Different Songs:

  • Program multiple RFID tags with different melodies.

  • Build a simple RFID-based music library.

Understanding Limitations

• Data Storage on RFID Tags:

  • RFID tags have limited storage capacity (typically up to 48 characters for the MFRC522).

  • Keep your musical sequences concise.

• Audio Quality:

  • Passive buzzers produce simple tones.

  • For better sound quality, consider using an active speaker with a DAC output.

• RFID Tag Compatibility:

  Ensure that your RFID tags are compatible with the MFRC522 reader.

Conclusion

You’ve successfully created an RFID Music Player using the Raspberry Pi Pico 2! This project combines RFID technology, music generation, and LED control to create an interactive and enjoyable experience. By storing melodies on RFID tags, you can easily share and play different tunes.