🎵 PiPod — Raspberry Pi Pico W MP3 Player

A lightweight embedded MP3 player built on the Raspberry Pi Pico W that reads audio files from a microSD card and supports browsing by songs, artists, genres, and playlists — without duplicating files.

This project focuses on efficient data handling and low-memory design suitable for microcontrollers.

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🚀 Features

• 🎧 MP3 playback from microSD card (SPI interface)
• 📂 Single-copy file storage (no duplication)
• 🔤 Browse Songs (sorted by title)
• 🎤 Browse Artists (grouped view)
• 🎼 Browse Genres (filtered via metadata)
• 📜 Playlist support using .m3u files
• ⚡ Fast startup using prebuilt metadata index
• 🧠 Memory-efficient (no database required)

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🧠 System Architecture

Due to the limited resources of the RP2040 (264KB RAM), this project avoids heavy solutions like SQLite.

Instead, it uses:

• A flat file system (FAT32)
• A metadata index file (songs.csv)
• Pointer-based indexing in memory

Conceptual Model

songs[]        -> master list of all songs
byTitle[]      -> sorted view (Songs menu)
byArtist[]     -> grouped view (Artists menu)
byGenre[]      -> filtered view (Genre menu)
playlist[]     -> dynamic list from .m3u files

All views reference the same MP3 file paths.

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💾 microSD Card Setup

Format

FAT32

Directory Structure

/music/
    song1.mp3
    song2.mp3
    song3.mp3

/index/
    songs.csv

/playlists/
    chill.m3u
    workout.m3u

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📄 Metadata Index (songs.csv)

To avoid parsing MP3 files on-device, metadata is precomputed.

Example

title,artist,genre,path
Song A,Artist X,Rock,/music/songA.mp3
Song B,Artist Y,Jazz,/music/songB.mp3

Why use this?

• Faster boot time
• Simpler firmware
• Lower CPU usage

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📜 Playlists (M3U)

Playlists are stored as standard .m3u files.

Example

/music/song1.mp3
/music/song3.mp3
/music/song7.mp3

The player reads file paths and maps them to the internal song list.

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📱 Menu System

> Songs
  Artists
  Genre
  Playlists

Behavior

Menu	Action
Songs	Sort all songs by title
Artists	Group songs by artist
Genre	Filter songs by genre
Playlists	Load .m3u file and play list

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⚙️ Firmware Overview

Core Data Structure

typedef struct {
    char title[64];
    char artist[48];
    char genre[32];
    char path[128];
} Song;

Startup Flow

1. Initialize SPI + microSD
2. Mount FAT filesystem
3. Load songs.csv
4. Populate songs[]
5. Build indexes:
   • Sorted (title)
   • Grouped (artist)
   • Filtered (genre)

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🔄 Sorting & Indexing

To minimize memory usage:

• Use pointer arrays instead of copying structs
• Sort using qsort
• Build lightweight lookup tables

Example:

Song* byTitle[MAX_SONGS];

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🛠️ Hardware Requirements

• Raspberry Pi Pico W
• microSD card module (SPI)
• microSD card (FAT32)
• Audio output:
  • DAC / PWM / I2S
  • or MP3 decoder (e.g., VS1053)

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🧑‍💻 Build & Flash

Requirements

• Pico SDK
• CMake
• ARM GCC toolchain

Build

mkdir build
cd build
cmake ..
make

Flash

• Hold BOOTSEL on Pico W
• Copy .uf2 file to device

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⚡ Performance Notes

• Avoid scanning /music at runtime for large libraries
• Use songs.csv for fast initialization
• Keep metadata structures small to fit RAM constraints

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🧰 Optional: Index Generator

You can generate songs.csv using a Python script:

• Scan /music
• Extract ID3 tags
• Output CSV

Suggested library:

mutagen

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🔮 Future Improvements

• Search functionality
• Album-based navigation
• Shuffle / repeat modes
• Display (OLED/LCD)
• Bluetooth audio
• WiFi sync using Pico W

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📜 License

MIT License

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👤 Author

Ethan Macson
GitHub: https://github.com/EMacson

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💡 Notes

This project demonstrates:

• Embedded systems design
• Efficient data structures under memory constraints
• File system handling on microcontrollers
• Real-time audio pipeline considerations