ESP32 Bluetooth MP3 Player

This project is a proof of concept and an experiment to build a Bluetooth A2DP source device using an ESP32. It reads MP3 files from a microSD card and streams the audio wirelessly to Bluetooth headphones or speakers.

Features

• A2DP Source: The ESP32 acts as an A2DP source, not a sink, meaning it streams audio to a device like Bluetooth headphones.
• MicroSD Card: Reads MP3 audio files from a microSD card, supporting a simple file system navigation.
• Playlist Management: Automatically scans the SD card for .mp3 files and creates an alphabetical playlist.
• Serial Control: Provides a basic command-line interface via the serial monitor to control playback (play, pause, next, previous) and manage the playlist.
• AVRC Support: Responds to playback control commands (play, pause, next, previous) sent from the connected Bluetooth device.

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Project Structure & Dependencies

This project is built upon the fantastic libraries by Phil Schatzmann. A huge thank you for these tools, which make this project possible!

• arduino-audio-tools: Handles audio processing and decoding.
• ESP32-A2DP: Manages the Bluetooth A2DP source functionality.
• arduino-libhelix: Provides the MP3 decoding engine (based on the Helix MP3 decoder).

Hardware Requirements

• ESP32 (I used ESP32-WROOM-32D, but any ESP32 board should work)
• MicroSD card reader module
• MicroSD card with MP3 files
• Connecting wires

Connect your SD card reader to the ESP32. The code is configured for the CS pin to be on GPIO5. You may need to adjust this constant (SD_CS_PIN) in the code to match your wiring.

The default SPI pins on the ESP32 are:

• MISO: GPIO19
• MOSI: GPIO23
• SCK: GPIO18
• SS (Chip Select): GPIO5

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Getting Started

1. Software Setup

To get started, you'll need to use PlatformIO.

• Install PlatformIO: If you haven't already, follow the official PlatformIO installation guide.

• Clone the Repository: Clone this project's repository to your local machine.

  git clone https://github.com/GiacoBot/ESP32MP3
  cd ESP32MP3

• Initialize Submodules: This project uses several libraries as Git submodules. Run the following command to download them:

  git submodule update --init --recursive

2. Hardware and Code Configuration

• Connect Hardware: Wire your SD card reader to the ESP32. The code is configured for the CS pin to be on GPIO5. If you've used a different pin, you'll need to update the SD_CS_PIN constant in the code to match your wiring.

• Target Device Name: By default, the code is set to connect to a device named "Lenovo LP40". You can change this to your desired Bluetooth device's name by modifying the TARGET_DEVICE_NAME constant in the code.

  const char* TARGET_DEVICE_NAME = "YOUR DEVICE NAME HERE";

• Prepare Your MP3 Files: The audio library requires MP3 files to have a sample rate of 44100 Hz. You can use a tool like ffmpeg to convert your files. Here's a command for converting a single file:

  ffmpeg -i input.mp3 -ar 44100 output.mp3

  Once converted, place the MP3 files on your microSD card and insert it into the reader.

3. Uploading the Code

• Open Project in VS Code: Launch VS Code and open the project folder.

Important

The PlatformIO project is located within the Software folder. When you open this project in VS Code, make sure you open the Software directory, not the root of the repository, to ensure PlatformIO can find all the necessary files.

• Upload: Use the PlatformIO toolbar in VS Code to build and upload the sketch to your ESP32 board.

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Usage

1. Connect ESP32: Power on your ESP32 board.

2. Open Serial Monitor: Open the Serial Monitor in VS Code (it should already have the baud rate set to 115200). The ESP32 will automatically scan the SD card and build the playlist.

3. Control Playback: Once connected, you can use the commands listed below in the Serial Monitor. The project also supports playback commands sent directly from your connected device (e.g., play/pause buttons on your headphones).

   • c: Connect to the device specified by TARGET_DEVICE_NAME.
   • d: Disconnect from the current Bluetooth device.
   • p: Pause or resume playback.
   • n: Play the next track in the playlist.
   • b: Play the previous track.
   • l: List all tracks on the playlist.
   • 1-9: Play a specific track number (e.g., typing 3 will play the third song).
   • r: Rescan the SD card to update the playlist.
   • s: Show the current playback status.
   • h: Display the help message.

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This project serves as a great starting point for anyone looking to experiment with ESP32 audio streaming and Bluetooth functionality. Feel free to fork it, modify it, and expand on its features!