OpenCircuit

Local-first, no-cloud health data for the RingConn Gen 2/3 and Air smart ring — read all metrics over Bluetooth LE and write them to Apple Health. Inspired by openwhoop, which does the same for the Whoop 4.0.

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OpenCircuit is the user-facing name (home screen / store). The Xcode target, the bundle id (com.standardsoftwaresolutions.opencircuit), and the OpenCircuitKit Swift package keep their original internal names for continuity. See docs/ROADMAP.md for status.

⚠️ Not affiliated with RingConn. OpenCircuit is an independent interoperability project — not affiliated with, authorized, or endorsed by RingConn or JZ_Tech. "RingConn" is a trademark of its respective owner. OpenCircuit is not a medical device. Privacy: docs/PRIVACY.md · License: LICENSE (MIT).

The RingConn app sends your data to RingConn's cloud (AWS, UK). OpenCircuit keeps it on your devices: the ring talks BLE straight to a client you control, which writes into Apple Health. No subscription, no third-party server.

Dashboard, sleep and activity insights, and live workout tracking — all from data decoded locally from your RingConn.

Every metric below is decoded on-device from the ring's own Bluetooth stream and written to Apple Health — nothing is sent to a server.

Health metrics → Apple Health

• ❤️ Heart rate — live, all-day, and during workouts
• 🫀 Resting heart rate
• 📈 Heart-rate variability (HRV)
• 🩸 Blood oxygen (SpO₂)
• 🌬️ Respiratory rate
• 🌡️ Skin temperature (overnight)
• 👣 Steps + an active-energy estimate
• 😴 Sleep — duration plus an on-device sleep-stage estimate (the ring sends no stage labels, so staging is computed locally and clearly labeled "est.")

Ring & charging-case status, live in the app

• 🔋 Ring battery %, raw voltage, and time-to-empty / time-to-full estimates
• ⚡ Charging detection — knows the instant the ring is on the charger
• 🧳 Charging-case battery % and whether the case itself is charging
• 🖐️ Wear detection — auto-measurement pauses when the ring is off-wrist or charging

How it connects

• 🔗 Standalone, no cloud key — the ring's per-connection authentication is fully reverse-engineered (an SM3 challenge keyed only on the ring's own MAC), so OpenCircuit connects and streams on its own, with no RingConn account or app needed for everyday use. A ring you've already set up with the official app is bonded and works immediately. (One case is still being verified: a brand-new ring that has never been activated in the official app on any phone — see issue #106.)
• 💍 Works with any RingConn Gen 2 ring, and multiple rings per phone.
• 🔄 Background sync, keepalive, and periodic auto-measure for continuous tracking.

OpenCircuit writes standard Apple Health data types, so any app that reads from Apple Health can use your RingConn data — including recovery/readiness apps like Bevel and Athlytic (both on the App Store), which normally pull from an Apple Watch, Oura, or Whoop. OpenCircuit becomes the bridge:

RingConn Gen 2  →  OpenCircuit (BLE, on-device)  →  Apple Health  →  Bevel / Athlytic

Wear your RingConn, let OpenCircuit sync it to Apple Health, and get Bevel's or Athlytic's recovery, readiness, strain, and sleep insights on top of ring data — no Oura or Whoop subscription required.

• Nothing leaves your phone except the data you choose to write into Apple Health.
• No RingConn cloud account, no subscription, no third-party server — the ring talks BLE straight to a client you control.
• All decoding and analytics run on-device; raw BLE captures used for protocol reverse-engineering are gitignored and never committed — only decoded findings live in docs/PROTOCOL.md.

┌─────────────────────── iOS App (Swift) — Phase 3+ ─────────────────────┐
│  CoreBluetooth  →  RingConn codec  →  Analytics  →  HealthKit (write)   │
│                          ↕                                              │
│                    Local store (SwiftData) ── sync cursor              │
└────────────────────────────────────────────────────────────────────────┘
        ▲ protocol spec produced by ▼
┌──── desktop/  RE workbench (Python + bleak) — Phase 1–2 (current) ──────┐
│  sniff app traffic → dissect → replay commands → decode each metric     │
└─────────────────────────────────────────────────────────────────────────┘

Only openwhoop's analytics (sleep/HRV/strain detection) port across devices; its BLE transport and packet parser are Whoop-specific and are rewritten here. HealthKit only exists on iOS, and iOS BLE must use CoreBluetooth, so the final data-writing app must be native Swift — the desktop workbench is the throwaway tool that decodes the protocol first.

cd desktop
python -m venv .venv && . .venv/Scripts/activate   # Windows; use bin/activate on *nix
pip install -r requirements.txt

python -m opencircuit scan          # find the ring, list services/characteristics
python -m opencircuit listen        # connect and log every notification (hex)
python -m opencircuit decode-log captures/btsnoop_hci.log   # parse an Android HCI capture

OpenCircuit is free and open-source. If it's useful to you, you can support development:

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For interoperability and personal data ownership. You own the ring and your data. Don't redistribute RingConn firmware or proprietary assets. The BLE protocol facts in docs/PROTOCOL.md are observations of traffic from your own device.