garmin-ble 0.2.2

A Python library for interacting with Garmin proprietary BLE protocols.

garmin-ble

A clean-room Python implementation of Garmin's proprietary BLE protocol (GFDI V2). Stream live telemetry from your Garmin watch directly to your computer: no cloud, no phone, no Garmin Connect required.

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Features

• Live Telemetry — stream real-time sensor data over BLE without Garmin Connect:
  • ❤️ Heart Rate & Resting Heart Rate
  • 🚶 Daily Steps & Goal
  • 📊 Heart Rate Variability (HRV)
  • 🫁 Blood Oxygen (SpO2)
  • 🌬️ Respiration Rate
  • 🔥 Calories (total & active)
  • ⚡ Intensity Minutes
  • 🧘 Stress Level
  • 🔋 Body Battery
  • ⌚ Accelerometer
• On-Demand Service Registration — telemetry services start only when you ask. No unwanted data streaming.
• Protocol Decoding — full implementation of the Garmin GFDI V2 stack:
  • Automated handshake (CLOSE_ALL, REGISTER_ML)
  • MLR (Multi-Link Routing) packet multiplexing
  • COBS (Consistent Overhead Byte Stuffing) encoding/decoding
  • Compiled Protobufs for gdi_smart_proto
  • CRC16 integrity checking
• Automatic Reconnection — survives BLE drops with exponential backoff
• Keep-Alive Heartbeat — periodic time-sync to maintain the link
• Hackable — pure Python, no binary blobs, no proprietary SDKs

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Installation

pip install garmin-ble

Or install from source with dev dependencies:

git clone https://github.com/gwerneckp/garmin-ble.git
cd garmin-ble
pip install -e ".[dev]"

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Quick Start

import asyncio
from garmin_ble import GarminClient, GarminService

def on_heart_rate(hr, resting_hr):
    print(f"❤️  {hr} BPM (Resting: {resting_hr} BPM)")

async def main():
    client = GarminClient()
    client.on("hr", on_heart_rate)

    if await client.connect():
        # Register and start only the services you want
        await client.register_and_start_service(GarminService.REALTIME_HR)
        print("Connected! Streaming data...")
        await client.start_sync_loop()

asyncio.run(main())

[!TIP] Make sure your watch is not connected to your phone via Bluetooth — Garmin watches only allow one BLE connection at a time.

[!IMPORTANT] Telemetry services are not auto-started. Use register_and_start_service() for each service you need (e.g., GarminService.REALTIME_STEPS, GarminService.REALTIME_ACCELEROMETER). Only the GFDI control channel is registered automatically.

See the examples/ directory for more complete usage patterns — including basic_telemetry.py (simple start), full_demo.py (advanced features), and tilt_volume.py (accelerometer-driven Mac volume control).

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Status & Roadmap

See the GitHub Issues for the full breakdown of planned features, known gaps, and in-progress work. Milestones map to release versions:

Phase	Goal	Status
1	🏗️ BLE transport & handshake	✅ Done
2	📡 Live telemetry streaming	✅ Done
3	🧠 Protobuf settings & device state	🔄 In progress
4	🔔 Notifications & media control	⏳ Planned
5	📁 File transfers (FIT / GPX downloads)	⏳ Planned
6	🗄️ Persistence & dashboard	⏳ Planned

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Design Philosophy

garmin-ble is a wire-protocol library, not a feature-complete application. It knows how to encode, send, decode, and respond to Garmin's BLE protobufs — and nothing more.

This means:

• The library does not fetch weather from OpenWeatherMap, sync calendars via CalDAV, or play sounds when the watch says "find my phone".
• Instead it provides the building blocks — protobuf encode/decode, callbacks for incoming messages, and transport helpers.
• Callers wire up the OS integration, external APIs, and user-facing features.

This keeps the library focused, testable, and free of the endless feature creep that plagues integration-heavy projects.

Consider using Gadgetbridge instead if: you want a full-featured open-source replacement for the Garmin Connect app on your Android phone.

Project Mission

Own your data. Garmin devices capture a wealth of physiological data, but Garmin Connect locks it behind a cloud service. This library gives you direct, programmatic access to your watch over BLE — no internet required.

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Acknowledgements & License

This project builds on the extraordinary reverse-engineering work of the Gadgetbridge team. The protocol logic, COBS decoding, and .proto schemas are derived from their open-source Java implementation.

Licensed under the GNU Affero General Public License v3.0 (AGPL-3.0) — see LICENSE for details.