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GLYPH Voice Kit

Firmware: transport-r6App: v0.11.0License: MITESP32-C6 RISC-V

GitHub Repository

Browse source code, report issues, and check technical specifications on pcbcupid/Glyph-Voice.

Download App & Firmware

Grab the prebuilt Android APK (glyph-voice-0.11.0.apk) and ready-to-flash binary files directly from GitHub Releases.

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1. What is the GLYPH Voice Kit?

The GLYPH Voice Kit is a portable, button-operated voice transcription and AI note-taking system. By pairing the GLYPH C6 development board with a high-performance G-Sense 1-Channel Microphone (T5848) and an Android companion app, you can capture spoken voice anywhere and instantly convert it into written text.

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How It Works (The Simple Version)

  1. Press to Talk: Tap the BOOT button on your GLYPH C6 board to begin speaking.
  2. Audio Streaming: The board captures your voice through the digital I2S microphone, filters the audio, and streams it wirelessly to your phone’s personal Wi-Fi hotspot over a local WebSocket.
  3. On-Device Speech-to-Text: The Android companion app transcribes your words in real time using an offline, on-device AI model (NVIDIA Parakeet). No internet connection or cellular data is needed!
  4. Instant AI Summary (Optional): When you finish speaking, the app can automatically summarize your notes into a clean, concise paragraph using DeepSeek or OpenAI.

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2. Quick Start: 4 Easy Steps

1

Wire Your Hardware

Connect the G-Sense T5848 Microphone to your GLYPH C6 with 5 jumper wires as shown in the Wiring Table.
2

Flash the Firmware

Download the ready-to-use firmware binary from GitHub Releases and flash it to your GLYPH C6 using Web Flasher or esptool.py.
3

Configure Wi-Fi Credentials

Power on your board. Connect your phone to the board’s setup network (GLYPH-Setup-XXXXXX), open http://192.168.4.1/ in your browser, and enter your phone hotspot name and password.
4

Open App & Start Talking

Install glyph-voice-0.11.0.apk from GitHub Releases, turn on your 2.4 GHz phone hotspot, tap Connect in the app, and click the BOOT button to record!

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3. Hardware & Wiring

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Bill of Materials (What You Need)

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Pin Connection Table

Connect your microphone directly to your GLYPH C6 using the following pin mapping:
USB CDC Setting: Because GPIO 16 and GPIO 17 share internal lines with UART0, ensure USB CDC On Boot is enabled in the Arduino IDE tools menu (Tools → USB CDC On Boot → Enabled) when compiling firmware from source.

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4. Setting Up the Firmware

You can either flash the precompiled binary directly or build the sketch from source in the Arduino IDE.
  1. Download glyph-voice-c6-0.11.0.bin from Releases · pcbcupid/Glyph-Voice.
  2. Connect your GLYPH C6 board to your computer with a USB-C cable.
  3. Run the following command in your terminal:

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Wi-Fi First-Time Setup Portal

When you turn on the board for the first time, it creates its own Wi-Fi setup hotspot:
  1. Connect: On your phone or laptop, look for the Wi-Fi network named GLYPH-Setup-XXXXXX (where XXXXXX is part of your board’s MAC address).
  2. Password: Enter glyphvoice.
  3. Open Portal: Navigate to http://192.168.4.1/ in your browser.
  4. Save Hotspot Details: Enter your phone’s Wi-Fi hotspot name (SSID) and password, then tap Save. The GLYPH C6 will reboot and connect to your phone automatically.
  5. Need to Reconfigure Later? While the board is disconnected from Wi-Fi, press and hold the BOOT button for 5 seconds to bring back the setup portal.

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5. Android Companion App

The open-source companion app manages the connection, runs the on-device AI transcription model, and saves your conversation history.

Download Android APK

Download glyph-voice-0.11.0.apk from the official releases page and install it on your device.

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App Highlights

  • Zero Intrusive Permissions: The app does not request phone microphone access, location, or file storage permissions.
  • Background Recording: Runs as a persistent foreground service so recording and transcription continue smoothly even if you lock your screen.
  • Searchable History: All previous transcriptions and summaries are stored locally in an embedded SQLite database on your phone.

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How to Connect

  1. Enable your phone’s Personal Hotspot (make sure 2.4 GHz band or Extend Compatibility is turned ON).
  2. Turn on your GLYPH Voice hardware.
  3. Open the GLYPH Voice app on your phone and tap Connect.
  4. The app automatically discovers the board on your hotspot within 3 seconds.
  5. Click the BOOT button on the GLYPH C6: live words will begin appearing on your screen as you speak!

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6. Speech Recognition: Offline vs Cloud

The app gives you the flexibility to transcribe completely offline or connect to cloud speech services.

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Offline Parakeet Model

The default engine uses an optimized INT8-quantized export of NVIDIA’s Parakeet model running via sherpa-onnx. The weights are packaged with the app release and extracted automatically the first time you tap Connect. It provides fast, accurate English transcription directly using your phone’s processor.

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Using Cloud Transcription (Optional)

If you prefer using an external cloud service (such as OpenAI Whisper):
  1. Open the right drawer in the app and choose Speech recognition → Cloud.
  2. Enter your OpenAI-compatible endpoint URL (e.g., https://api.openai.com/v1/audio/transcriptions).
  3. Paste your API key. Keys are encrypted securely inside your phone’s hardware-backed Android Keystore.

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7. Automated AI Summaries

If you want your spoken voice notes automatically organized into neat summaries:
  1. Open the right drawer in the app and tap Connect your API.
  2. Select your provider:
    • DeepSeek: Powered by DeepSeek’s conversational models.
    • OpenAI: Powered by models like gpt-4.1-mini.
  3. Paste your API Key.
Whenever you finish a recording longer than 2 seconds, the app automatically formats the transcript into a natural, easy-to-read summary paragraph. You can toggle between the original verbatim transcript and the summary at any time!

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8. Simple Troubleshooting Tips

  • Board not connecting to hotspot?
    Ensure your phone’s hotspot is broadcasting on the 2.4 GHz frequency band. The ESP32-C6 Wi-Fi radio cannot connect to 5 GHz-only hotspots.
  • App doesn’t discover the board?
    Turn off AP Isolation or Client Isolation in your phone’s hotspot settings so the board and phone can communicate over local UDP.
  • Audio sounds empty or silent?
    Double check that the SD / DOUT pin of the T5848 mic is connected to GPIO 23 and WS / LRCLK is wired to GPIO 17.
  • Accidentally entered flashing mode?
    If you hold the BOOT button while plugging in the USB cable, the board enters ROM bootloader mode. Simply unplug and plug it back in without touching the button.

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9. Source Code & References

The complete source code for firmware, companion app, audio processing core, and hardware design is fully open source under the MIT license: