TrikiVR

Middleware that turns cheap Żabka Triki BLE gadgets into SlimeVR full-body trackers.

It connects to one or more Triki devices over Bluetooth LE, decodes their IMU stream, runs sensor fusion, and feeds the resulting orientation into the SlimeVR Server by emulating tracker firmware over UDP (:6969).

How it works

noble scan ──"Triki"──▶ TrikiDevice (one per device)
   subscribe NUS TX notify ─▶ decode (14-byte frame → gyro °/s + accel g)
   ─▶ VQF fusion (6-axis, per device) → quaternion
   ─▶ SlimeVRBridge: one EmulatedTracker per device
                                         │ UDP :6969 (handshake + rotation/accel)
                                         ▼
                                  SlimeVR Server

Built on the official SlimeVR packages (@slimevr/tracker-emulation, @slimevr/firmware-protocol, @slimevr/common). The Triki BLE protocol is ported from TrikiReader; orientation fusion is a TypeScript port of VQF (BasicVQF).

The hardware

• nRF52810 + ST LSM6DSL 6-axis IMU (no magnetometer).
• Nordic UART Service 6e400001-…; IMU notifications arrive on TX 6e400003-….
• 14-byte frames: header 22 00, then 6× int16 LE — gyro xyz ÷ 14.2857 (°/s), accel xyz ÷ 2048.0 (g).
• The IMU stream is started by writing 201000D007680003 to the RX characteristic.

Because there is no magnetometer, yaw drifts over time. This is normal for 6-DoF trackers — use SlimeVR's Reset / Mounting reset to re-align.

Project layout

src/
  main.ts                     Electron main: window, IPC, owns TrackingService
  preload.mts                 contextBridge → window.trikivr
  core/
    TrackingService.ts        wires TrikiManager ↔ SlimeVRBridge
    triki/
      constants.ts            NUS UUIDs, frame layout, scales, start command
      decode.ts               frame reassembly + decode (unit-tested)
      vqf.ts                  BasicVQF port (MIT, dlaidig/vqf)
      fusion.ts               6-axis VQF orientation filter
      TrikiDevice.ts          one BLE peripheral: connect, subscribe, fuse
      TrikiManager.ts         noble scan + multi-device lifecycle
    slimevr/
      SlimeVRBridge.ts        one EmulatedTracker per device
      mapping.ts              IMU → SlimeVR quaternion axis remap
  static/                     renderer GUI (html/css/js)

Build & run

npm install
npm run rebuild        # rebuild native BLE bindings against Electron's ABI
npm run setup:linux    # Linux only: grant BLE permission to the Electron binary
npm start              # builds (tsc + copy static) and launches Electron

npm test runs the decode/parser unit tests.

Native bindings: @stoprocent/noble ships prebuilt binaries for Node, but Electron uses a different ABI, so npm run rebuild (electron-rebuild) is required before npm start. If your environment defers npm install scripts (e.g. an allow-scripts sandbox), approve them for @stoprocent/noble, @stoprocent/bluetooth-hci-socket and electron first.

Bluetooth permissions

The app detects when it can't use Bluetooth and shows a banner in the GUI with a platform-specific fix (the adapter check lives in src/core/triki/adapter.ts):

• Linux — opening a raw HCI socket needs CAP_NET_RAW + CAP_NET_ADMIN. Run npm run setup:linux once (re-run after any npm install, which replaces the Electron binary). It grants the capability to the local Electron binary and registers Electron's bundled libs with the loader cache (required because file capabilities trigger glibc secure-execution mode). Undo with scripts/teardown-linux-ble.sh. Alternatively, run the app as root.
• macOS — grant Bluetooth access in System Settings → Privacy & Security → Bluetooth (the app reports unauthorized until you do).
• Windows — works out of the box; just ensure Bluetooth is on.

Using it

1. Start the SlimeVR Server.
2. Launch TrikiVR, press the button on each Triki to wake it, then click Start scanning.
3. Click Connect on each discovered Triki — each appears as a separate tracker in SlimeVR.
4. Assign body parts and run SlimeVR's reset flow as usual.

If pitch/roll/yaw come out swapped or inverted, adjust the AxisMap in src/core/slimevr/mapping.ts — the single place that maps the IMU frame to SlimeVR's convention.

License

MIT. Includes a TypeScript port of VQF by Daniel Laidig (MIT).