🎤 XIAO Audio Transcriber

A complete BLE audio streaming and transcription system using the Seeed Studio XIAO nRF52840 Sense board with real-time speech-to-text capabilities.

🌟 Features

🔧 Firmware (XIAO Board)

• Real-time Audio Capture - 16kHz microphone streaming via BLE
• Custom BLE Audio Service - Optimized for continuous audio streaming
• Professional Audio Quality - 16-bit PCM, mono channel
• Continuous Streaming - 160 samples per packet, 10ms intervals
• Comprehensive Debugging - Detailed serial output and monitoring

📱 React Web App

• BLE Audio Recording - Capture audio directly from XIAO board
• Live Transcription - Real-time speech-to-text using Deepgram
• Audio Playback - Play recorded audio with proper audio context
• Modern UI - Beautiful, responsive interface with real-time status
• Cross-platform - Works on desktop and mobile browsers

🛠 Hardware Requirements

• Seeed Studio XIAO nRF52840 Sense board
• USB-C cable for programming and power
• Computer with Bluetooth capability
• Web browser with Web Bluetooth support (Chrome/Edge recommended)

📋 Software Requirements

For Firmware Development

• Nordic Connect SDK v3.1.1 or compatible
• nRF Command Line Tools
• VS Code with nRF Connect extension (recommended)

For React App

• Node.js (v14 or higher)
• npm package manager
• Modern web browser with Web Bluetooth support

🏗 Project Structure

├── src/                              # Firmware source code
│   ├── main.c                        # Main application and BLE setup
│   ├── custom_audio_service.c        # Audio streaming service
│   └── custom_audio_service.h        # Service definitions
├── reactapp/                         # React web application
│   ├── src/
│   │   ├── App.js                    # Main React component
│   │   └── components/
│   │       ├── BLEConnection.js      # BLE connection management
│   │       ├── AudioRecorder.js      # Audio recording functionality
│   │       └── DeepgramTranscriber.js # Speech-to-text integration
│   ├── public/
│   ├── package.json                  # Dependencies
│   └── README.md                     # React app documentation
├── CMakeLists.txt                    # Firmware build configuration
├── prj.conf                          # Project configuration
└── README.md                         # This file

🚀 Quick Start

1. Build and Flash Firmware

# Build the firmware
west build -b xiao_ble/nrf52840/sense

# Flash via UF2 bootloader
# 1. Double-click reset button on XIAO board
# 2. Copy build/zephyr/zephyr.uf2 to XIAO-SENSE drive

2. Start React App

# Navigate to React app directory
cd reactapp

# Install dependencies
npm install

# Start development server
npm start

3. Use the Application

1. Open browser to http://localhost:3000
2. Connect to XIAO board - Click "Connect to XIAO Board"
3. Start Recording - Click "Start Recording" and speak into XIAO
4. Live Transcription - Click "Start Transcription" for real-time speech-to-text
5. Playback - Play recorded audio or download as WAV file

🔧 Technical Details

Firmware Specifications

• Audio Format: 16-bit PCM, 16kHz sample rate, mono
• BLE Streaming: 160 samples per packet (320 bytes), 10ms intervals
• Device Name: "MicStreamer"
• Service UUID: 12345678-1234-5678-1234-567812345678
• Characteristic UUID: 12345679-1234-5678-1234-567812345678

React App Features

• Web Bluetooth API - Direct BLE communication
• Audio Context - Professional audio processing
• Deepgram Integration - Live speech-to-text transcription
• Real-time Status - Stream monitoring and packet counting
• Cross-browser Support - Works on Chrome, Edge, and other modern browsers

🎵 Audio Flow

XIAO Microphone → BLE Stream → React App → Deepgram API → Live Transcription
                ↓
            Audio Recording → WAV File → Playback/Download

📱 Browser Compatibility

Browser	Web Bluetooth	Audio Context	Status
Chrome	✅ Yes	✅ Yes	✅ Full Support
Edge	✅ Yes	✅ Yes	✅ Full Support
Safari	❌ No	✅ Yes	⚠️ Limited (No BLE)
Firefox	❌ No	✅ Yes	⚠️ Limited (No BLE)

🔍 Debugging

Serial Output (Firmware)

Connect to serial at 115200 baud:

screen /dev/cu.usbmodem1101 115200

Browser Console (React App)

• F12 → Console tab
• Look for BLE connection logs
• Monitor audio packet reception
• Check transcription status

Expected Output

🎤 XIAO MIC (BLE): received 160 samples
🎵 Transcribing XIAO MIC: sent 160 samples to Deepgram
📝 Deepgram transcript received: "Hello world"

⚙️ Configuration

Deepgram API Key

Update the API key in reactapp/src/components/DeepgramTranscriber.js:

const DEEPGRAM_API_KEY = 'your-api-key-here';

Audio Parameters

• Sample Rate: 16kHz (matches firmware)
• Channels: 1 (mono)
• Bit Depth: 16-bit
• Encoding: linear16 (for Deepgram)

🚨 Troubleshooting

BLE Connection Issues

• Ensure XIAO board is powered and running firmware
• Check browser has Bluetooth permissions
• Try refreshing the page and reconnecting
• Verify "MicStreamer" appears in device list

Audio Issues

• Check serial output for streaming status
• Verify audio stream is active in React app
• Ensure XIAO microphone is not blocked
• Test with different audio levels

Transcription Issues

• Verify Deepgram API key is correct
• Check network connection
• Monitor browser console for errors
• Ensure audio packets are being sent to Deepgram

📚 API Reference

BLE Service

• Service UUID: 12345678-1234-5678-1234-567812345678
• Audio Data Characteristic: 12345679-1234-5678-1234-567812345678
• Properties: Notify, Write

Deepgram Configuration

• Model: nova-3 (latest)
• Language: en-US
• Format: linear16
• Sample Rate: 16000 Hz

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

📄 License

This project is open source. Feel free to modify and distribute according to your needs.

🙏 Acknowledgments

• Seeed Studio for the excellent XIAO nRF52840 Sense board
• Nordic Semiconductor for the nRF Connect SDK
• Deepgram for the speech-to-text API
• React and Web Bluetooth communities

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🎤 XIAO Audio Transcriber
Real-time BLE audio streaming with live speech-to-text transcription

Built with ❤️ for the XIAO nRF52840 Sense community