---
title: Hardware events
description: What Meta Ray-Ban surfaces today via glasses.runtime.events, connection.state, and toggles — and which hardware-alert streams aren't exposed yet. No IMU API.
type: guide
platform: all
vendor: meta
related:
  - /docs/guides/handle-disconnects
  - /docs/concepts/capabilities
  - /docs/vendors/meta
  - /docs/reference/errors
---

> **There is no IMU, head-pose, accelerometer, gyroscope, or gaze stream on Meta Ray-Ban.** The Meta Device Access Toolkit does not expose raw motion sensors to third-party apps, and there is no phone-side workaround. If you've seen those promised elsewhere, it was aspirational — they are not part of the SDK. This page documents what the glasses *do* surface today and what's on the roadmap.

What you get today is a runtime **event stream** plus a set of **hardware conditions** that surface through connection state and toggles. This page covers both, honestly scoped to what ships.

> Kotlin leads the snippets and is the source of truth; the iOS surface mirrors it via `glasses.runtime.events`.

## The runtime event stream

`glasses.runtime.events` is a `Flow<RuntimeEvent>` — the on-device event log surfaced to your app. `RuntimeEvent` is a sealed interface; subscribe and `filterIsInstance` for the variant you care about:

```kotlin
import com.extentos.glasses.core.RuntimeEvent

scope.launch {
    glasses.runtime.events.collect { event ->
        when (event) {
            is RuntimeEvent.ToggleChanged ->
                // a runtime toggle changed (key, oldValue, newValue, source)
                onToggle(event.key, event.newValue)
            is RuntimeEvent.CoexistenceWarning ->
                // an audio/video coexistence conflict (blocked, reason)
                warnUser(event.reason)
            is RuntimeEvent.UnrecognizedUtterance ->
                // STT produced text that matched no registered phrase (rawTranscript)
                maybeSuggestHelp(event.rawTranscript)
            is RuntimeEvent.Log ->
                // a diagnostic log line (level, message, payload?)
                Unit
            is RuntimeEvent.Assistant ->
                // a Phase-4 assistant lifecycle event — see the assistant runtime
                Unit
        }
    }
}
```

The variants that ship today:

| Variant | Payload | Fires when |
|---|---|---|
| `ToggleChanged` | `key, oldValue, newValue, source` | A runtime toggle is mutated (by UI, voice command, or automation). |
| `CoexistenceWarning` | `blocked, reason` | **Declared, not yet emitted** — routing conflicts currently surface as `CoexistenceBlocked` errors on the affected call. |
| `UnrecognizedUtterance` | `rawTranscript` | **Declared, not yet emitted** — post-pivot the library does no phrase dispatch; match transcripts in your own handler. |
| `Log` | `level, message, payload?` | The library emits a diagnostic line. |
| `Assistant` | `event: AssistantEvent` | A Phase-4 [assistant runtime](/docs/concepts/assistant) lifecycle event (session start/end, user/assistant spoke, tool called, reconnected, error). |

`snapshotEvents()` returns the current buffer as a `List<RuntimeEvent>` if you'd rather poll than collect. In the browser simulator the same events flow to the structured [event log](/docs/concepts/transport-vs-app) (chips: errors / voice / camera / display / lifecycle / custom), queryable with `getEventLog`.

## Hardware conditions you can observe today

Two physical conditions of the glasses are surfaced — not as a sensor stream, but through the surfaces that already exist:

### Thermal and hinge state → `connection.state`

A fold — and, on the phone side, thermal pressure — ends the session. **Today the drop arrives as `Disconnected(DisconnectCause.DeviceDroppedConnection)`**; the dedicated typed causes below are declared but not yet produced by the core:

- **Thermal critical** (a phone-side `PowerManager` signal, not a glasses sensor) → reserved cause `DisconnectCause.ThermalCritical`. Flipping `battery_save_mode` on before reconnecting is still a good response to heat.
- **Hinges folded** → reserved cause `DisconnectCause.HingesClosed` (DAT doesn't expose hinge position; the fold shows up as the session ending).

Observe these the same way you handle any disconnect — branch on `Disconnected.cause`. See [Handle disconnects](/docs/guides/handle-disconnects#branch-on-the-disconnect-cause) for the full pattern. (A continuous, *non-disconnecting* thermal/hinge event stream with severity and temperature is planned — see below — but today these conditions are observable only at the point they drop the connection.)

### Battery-save and stream clamping → toggles + events

When `battery_save_mode` is on (set by the user, or by your app in response to thermal pressure), the library clamps any `videoFrames` stream to `LOW` resolution + 2 fps regardless of the config you requested, and emits a `camera_stream_clamped` event carrying the requested-vs-effective resolution/fps so the downgrade is observable. Observe `battery_save_mode` via `glasses.toggles.state`, and watch for the clamp in the event log. This is the signal to pair high-fps [video streams](/docs/guides/video-capture#continuous-frame-stream) with a downgrade path.

## Planned, not yet exposed

The Meta DAT SDK and the Extentos transport carry several hardware/lifecycle alerts internally, but **the last hop to customer code is not connected yet** — there is no consumer API for these as of the current release. Don't build against them; they are listed here so you know they're coming and don't mistake their absence for a bug:

| Planned event | Intended payload | Status |
|---|---|---|
| `thermal_warning` | `{ severity, temperatureCelsius }` | Future — today only via `Disconnected(ThermalCritical)` + `battery_save_mode`. |
| `hinges_closed` | hinge fold/unfold | Future — today only via `Disconnected(HingesClosed)`. |
| `audio_route_changed` | `{ from, to }` | Future — no consumer API yet. |
| `incoming_call_detected` | `{ callerNumber, callerName }` | Future — no consumer API yet. |
| `app_lifecycle_changed` | `{ state }` | Future — no consumer API yet. |
| `location_updated` | `{ latitude, longitude, accuracyMeters }` | Future — no consumer API yet. |
| `phone_notification_forwarded` | forwarded phone notification | Future — the `NotificationListenerService` emits it into the transport, but it isn't relayed to customer code yet. |

Two other sensor surfaces are earlier-stage research, not committed: `ambient_light_updated` and a `tap_gesture` (custom tap/swipe gestures are **not** in the public DAT toolkit — only phone-side buttons and voice are developer-accessible). Check `getPlatformInfo` for the live status of each, and the [Meta vendor page](/docs/vendors/meta) for the GA capability matrix.

## Related

- [Handle disconnects](/docs/guides/handle-disconnects) — branch on `Disconnected.cause` to react to thermal/hinge conditions.
- [Capabilities](/docs/concepts/capabilities) — the full capability catalog and what's GA vs future.
- [Vendors: Meta Ray-Ban](/docs/vendors/meta) — the GA capability matrix and DAT constraints.
- [Assistant runtime](/docs/concepts/assistant) — `RuntimeEvent.Assistant` lifecycle events.