Technical characteristics
How the ring works
The engineering behind the everyday moments — connectivity, charging, input, localization, hardware and security. Written to be scannable, and honest about what's still on the bench.
Connectivity
The ring joins your existing smart home as a standard control device — no proprietary hub. It supports two open paths so it fits whichever ecosystem you run.
| Primary protocol | Matter-over-Thread — the ring is a standard Matter Generic Switch node on a low-power Thread mesh. Works with Home Assistant, Apple Home and Google Home as a Matter fabric. |
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| Alternative path | BLE BTHome v2 (default build) — connectionless advertisements auto-discovered by Home Assistant; battery, charge state, firmware version and gesture events. |
| Control model | Local by design — gestures map to scenes, lights and devices on your own network, with no cloud round-trip required. |
| Radio maturity on this SoC | Thread and BLE co-exist via the standard multiprotocol scheduler. On the nRF54LM20A, BLE and Thread+BLE multiprotocol are rated Experimental in the current SDK. provisional |
| Ecosystem certification | Development attestation today; production factory data and CSA certification for Apple/Google ecosystems are a bring-up step. provisional |
On-click room localization
So a single gesture does the right thing in the room you're actually in. When you press, the ring attaches location to the event itself — no follow-up query — so your home can resolve "which room" as the click arrives.
| Instant coarse fix | On press-down, the ring reports its current Thread parent and the signal strength to it — free, zero extra radio-on time. Thread already picks the parent by best link, so it approximates the nearest anchor. |
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| Finer neighbour scan | A press also kicks off a neighbour scan (ranking nearby anchors by signal); it runs while the gesture is still being classified and rides along with the resolved event, or times out at ≈1 s so a click is never delayed. provisional |
| How it's carried | The button stays a plain, standard switch event (native to your home hub); location travels as two manufacturer-specific attributes the hub reads from cache — atomic with the click. |
| Resolution | Room-level. The hub maps radio addresses to rooms and applies smoothing + hysteresis. Sub-metre distance (Channel Sounding) is a possible future refinement, not shipped. provisional |
Wireless charging
The ring has no charging port or contacts. It charges inductively over its coil, and reports its own battery and power back to the pad over the same coil using backscatter — a load-modulated (ASK) link, so there's no separate radio for telemetry.
| Method | Contactless inductive power transfer over the ring's coil — no pins, no port, nothing to wear out. |
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| Telemetry link (BSC) | Backscatter: the ring modulates the coil's load impedance (ASK) so the charger sees battery %, charge state and received power live on the pad. Differential bi-phase, 2 kbit/s. |
| Operating point | ≈6.78 MHz WPT carrier; charge current up to ≈10 mA into the ring cell in the co-simulation model. Coil coupling / efficiency come from an EM study, not measured silicon. provisional |
Gesture input
Tactile buttons plus a knock/tap sensor, combined into a rich but learnable set of gestures — each one you can feel without looking.
| Buttons | Three domed tactile buttons under a seamless soft-touch membrane — single, double, triple and long presses. |
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| Knock / tap | An accelerometer turns a knock of the ring against a surface into its own gesture. |
| Combos | Buttons and knock combine — a knock while a button is held, or a knock just after a button press, is a distinct first-class gesture ("press 1, then knock twice"). |
| Tuning | Knock/tap thresholds are silicon defaults; the knock-vs-accidental feel needs tuning on the real ring. provisional |
Battery & power
A tiny curved cell and event-driven firmware: the ring wakes to act, then sleeps, so steady-state draw is small.
| Cell | Curved ≈21 mAh Li-Po (Grepow GRP160627), hugging the inside of the band behind the coil. |
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| Fuel gauge | nPM1304 PMIC fuel gauge; battery % and charge state reported while worn and while charging. |
| Battery life | Weeks of typical use is the target — but this is an estimate. Idle current on the current SDK carries a known regression that must be fixed first, and nothing has been measured on hardware. provisional |
Hardware & build
All the electronics live on one flex PCB that folds inside a metal shell, sealed under a moulded membrane with integrated button domes — one continuous part, no seams or gaskets.
| SoC | Nordic nRF54LM20A (Arm Cortex-M33) — BLE + Thread radio, the application core. |
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| Power management | Nordic nPM1304 PMIC — charger, 1.8 V rail, LED drivers and fuel gauge. |
| Sensors | BMA580 accelerometer (knock/tap input); INA236 power monitor on the received-power rail. |
| Construction | Rigid-flex PCB folded into an anodized-metal shell; over-moulded soft-touch membrane with domed buttons. Worn-ring inner diameter ≈21.5 mm (US 12 prototype). |
| Platform | Nordic Connect SDK (NCS) v3.2.0 / Zephyr. |
Security & updates
Firmware updates are cryptographically protected end to end, so only genuine, unmodified images can run on the ring.
| Secure boot | MCUboot verifies an ED25519/SHA-512 signature; the verification key is provisioned into hardware key storage (KMU). Only a correctly signed image boots. |
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| Encrypted updates | Update images are encrypted (ECIES-X25519); the ring decrypts and installs them, so images can't be read or tampered with in transit. |
| Delivery | Signed + encrypted DFU over BLE (mcumgr/SMP). Matter-over-Thread OTA is a candidate path pending partition budgeting. provisional |
| Key isolation (roadmap) | Moving crypto/keys into a TrustZone secure world (TF-M) so an app bug can never extract keys — planned after RF bring-up. provisional |