smartring — cloud-free presence lighting from a $10 ring

The $10 experiment

The Ti-Vision Smart Fitness Ring is a ~$10 ring — listed as "titanium," cheerfully plastic in person — that pairs with an ad-laden vendor app and speaks the Gadgetbridge-documented Lefun BLE protocol. The goal: talk to it directly — no cloud, no app, no phone — and see what it can really do.

The answer rewired the whole project.

The ring's circuit board seen through its clear housing — The PCB through the clear housing — Nordic-class MCU, optical PPG die, and *no working IMU*.

🔬The headline finding

The listing sells sleep tracking. The app shows steps and "shake for camera." Exhaustive testing proved a single thing that explains all of it:

This ring has no functional accelerometer. Every optical feature works; every motion feature is dead. It runs generic Lefun firmware on hardware carrying only the PPG die — so it politely advertises the step/sleep/gesture commands, then answers them with zeros.

Feature	Sensor	Result
Heart rate	optical PPG	✔ works
SpO₂	optical PPG	✔ works
Blood pressure (estimate)	optical PPG	✔ single value
Steps · Sleep	accelerometer	✘ dead — always 0
Shake → camera / find-phone	accelerometer	✘ dead — never fires

The pivot: with no shake-button to catch, there's no reason to hold a BLE connection open. Left free to advertise, the ring becomes a room beacon — and that's the foundation for presence lighting.

💡Follow-me lighting

Walk into a room, its lights come on; leave, they go off.

Animation: the ring moves between rooms and each room's lights follow

Each room's occupancy is fused from up to three independent estimators — whichever resolves the room first wins:

 ring advert ─▶  nearest-proxy tracker (custom, recency-weighted) ┐
 ring advert ─▶  Bermuda BLE trilateration                        ├─▶  room       ─▶  that room's
 mmWave      ─▶  ESPHome radar presence (instant, identity-blind) ┘    occupancy       button_lights
                                                                       (OR-fused)

🔵 BLE — knows who

Two independent estimators on the ring's adverts (a custom nearest-proxy tracker + Bermuda). Identity-aware, whole-house, but slow — a cheap ring advertises sparsely and can't wake on motion.

📡 mmWave — knows now (optional)

Instant, holds while you sit still, but identity-blind. Plug a radar into a room and it upgrades to sub-second response automatically — zero config change. The reference deployment currently runs on the ring's adverts alone.

🩹 Self-healing

Each room manages itself; lights fire on the occupancy rising edge only. A manually-darkened room stays dark; a room left lit by a missed transition is cleaned up on the next event.

🛡️ Graceful degradation

Radar down → BLE carries it. One tracker glitches → the other covers. Ring out of range → the room simply clears. No single point of failure.

Room tracking rides on ESPHome Bluetooth proxies — one per tracked room, standard and well-documented Home Assistant territory. This house runs ESP32-C3 devkits that triple-duty as advert proxies, iTag button holders, and BLE battery-monitor bridges.

🧩What's in the repo

`lefun_ring.py`	Standalone Python CLI + library for the ring's native BLE protocol. No HA needed.
`custom_components/lefun_ring/`	Home Assistant integration — routes through HA Bluetooth (local adapter or ESPHome proxies), sensors + services + real-time room tracking.
`ha-packages/lefun_ring.yaml`	The presence-lighting engine: fused occupancy, follow-me automation, per-room toggles, finder scripts.
`dashboard/`	Lovelace dashboards for the ring and the BLE-proxy fleet.

⚡Quick start

python3 -m venv .venv && .venv/bin/pip install -r requirements.txt

# one-time bond, then read live data
bluetoothctl pair <RING_MAC> && bluetoothctl trust <RING_MAC>
.venv/bin/python lefun_ring.py --address <RING_MAC> hr

For Home Assistant: copy custom_components/lefun_ring/ into your config, restart, and add the Lefun Ring integration — full instructions →

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