Aura Glasses BLE Protocol

Aura Glasses BLE protocol (Phase 3)

Phone is the hub. Glasses run lightweight firmware (reference: nRF52840) that exposes a custom GATT service and renders UTF-8 JSON GlassCard payloads on the lens UI.

GATT layout

UUID	Role
`f47ac10b-58cc-4372-a567-0e02b2c3d479`	Aura Glasses service
`f47ac10b-58cc-4372-a567-0e02b2c3d480`	CARD_OUT — phone writes GlassCard JSON
`f47ac10b-58cc-4372-a567-0e02b2c3d481`	EVENT_IN — glasses notify button events

Device name prefix: AuraGlass (for filtering scans).

GlassCard JSON (phone → glasses)

Same schema as in-app GlassCardCodec (v=1):

{
  "v": 1,
  "type": "incoming_call",
  "title": "Priya",
  "body": "Incoming voice call",
  "actions": [
    { "id": "decline", "label": "Decline" },
    { "id": "accept", "label": "Accept" }
  ],
  "meta": { "callId": "abc123" }
}

Payload limit: 512 bytes per write on EVT v1 (phone uses GlassCardCodec.encodeForBle).

Thumbnail (Gen 3)

`meta` key	Lens behavior
`imageRes`	Bundled icon id (phone shop demo); firmware maps to asset
`imageUrl`	HTTPS product/capture URL; fetch on Wi-Fi coprocessor, else placeholder box

Reference parser: firmware/aura-glasses-evt/nrf52/src/glass_card_parser.c.

Hardware action (glasses → phone)

{ "v": 1, "kind": "action", "actionId": "accept" }

The app maps actionId to the same handlers as the on-phone HUD (AuraGlassesBridge.handleHudAction).

Android client

AuraGlassesBleHub — connect by MAC, mirror cards, receive events
Settings → Aura Glasses (preview) → EVT hardware (BLE)
Permissions: BLUETOOTH_CONNECT, BLUETOOTH_SCAN (Android 12+)

Firmware checklist (EVT)

Expose service + characteristics above
On CARD_OUT write: parse JSON, render title/body/actions on display
On physical button: map to actionId, notify EVENT_IN
Optional: camera capture → phone via existing upload API (source=wearable)