I got a Garmin watch to work as a real Tesla key over Bluetooth - no phone, no cloud
My Garmin watch is now a real Tesla key over Bluetooth — no phone, no cloud.
I'm the developer of Wristla, a Tesla app for Garmin. This update adds something I wasn't sure was even possible on Connect IQ: the watch itself becomes a Tesla key over BLE. Not "phone relays a command" — the watch talks straight to the car, and the car unlocks as you walk up.
What made this hard:
- Connect IQ gives you a raw Bluetooth API and nothing above it. Everything the car expects had to be built from scratch in Monkey C — there is no library, no example, nothing to lean on.
- Instinct 3 has about 10 KB of free RAM once the app is running. Fitting a full secure session into that took as long as writing it did; most of the work was making things smaller, not making them work.
- The published clients get you part of the way and then stop matching reality. The rest came from weeks of measuring against an actual car, one failed attempt at a time.
What actually works on my car (Model Y) today:
- Passive entry and drive authorisation: the car sees the watch as a key, unlocks on approach, and lets you drive off — no card, no phone
- Direct BLE commands when the phone has no signal — underground garage, dead-zone parking
- A signal-strength "find my car" that shows distance in metres
Bluetooth when you're at the car, cloud when you're not. The app picks the route itself: if the car is in Bluetooth range the command goes straight to it, otherwise it goes through the Tesla Fleet API. Nothing to switch manually.
Works on most current Garmin watches — Instinct 3 and E, fēnix 7 and 8, epix, Forerunner, tactix, MARQ, Enduro, Descent and more.
Wristla is available in the Connect IQ Store and includes a 2-week free trial.
Happy to answer any questions.