Thermogatz AT-02 BBQ Thermometer in Home Assistant, Over Bluetooth

The Thermogatz AT-02 is a round Bluetooth grill thermometer. It has four sockets for food probes and one ambient probe that goes through the wall of the grill. It works well with its phone app, but the app is the only way to read it. There is no API.

I wanted the temperatures in Home Assistant, to graph a cook and get a notification when the meat is done. So I wrote an integration for it.

The product picture is the manufacturer’s.

What you get

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It updates every second, works through any Bluetooth adapter or ESPHome Bluetooth proxy that Home Assistant uses, and reconnects on its own.

How it works

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The thermometer advertises as AT-02 and needs no pairing. The integration connects, subscribes to one characteristic, and asks for the status and the temperatures. From then on it sends one frame per second.

55 aa 00 0f a1 | ff ff  ff ff  ff ff  05 50  ff ff  ff ff  00 bc | 04
                 p1     p2     p3     p4     p5     p6     ambient
                                      136.0 °C                18.8 °C

Seven slots in tenths of a degree, ffff meaning nothing plugged in. Battery comes from the status reply.

None of this is documented, so I took it from the phone app. I pulled the APK with adb, decompiled it with jadx, found the UUIDs, the start-up sequence and the notification parser, and then replayed it against the real thermometer from a Mac with bleak to confirm the numbers. The full protocol is in docs/protocol.md and the method is in docs/reverse-engineering.md.

Install

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Add https://github.com/phoinixgrr/thermogatz_ha to HACS as a custom repository (category Integration), install Thermogatz BBQ Thermometer and restart. The thermometer then shows up under Discovered.

An alert when the meat is done:

- alias: BBQ probe 1 reached 74 C
  triggers:
    - trigger: numeric_state
      entity_id: sensor.at_02_5f3e_probe_1
      above: 74
  actions:
    - action: notify.notify
      data:
        message: "Probe 1 is at {{ states('sensor.at_02_5f3e_probe_1') }} °C"

Good to know

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• The thermometer accepts one Bluetooth connection at a time, so Home Assistant and the phone app cannot be connected together. Disable the integration entry when you want the app.
• Only the AT-02 is tested. Your mileage will vary on other models and devices.

Where to find it

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Source, docs and releases: github.com/phoinixgrr/thermogatz_ha

This is an independent project, not affiliated with Thermogatz.

Happy Home Assistant grilling! 🥩🔥