Custom Firmware für das 4€ Xiaomi Thermometer LYWSD03MMC

 Durch die Möglichkeit Telink TLSR Mikrocontroller zu programmieren ist es mir nun endlich gelungen eine Custom Firmware für die günstigen Xiaomi Thermometer LYWSD03MMC zu erstellen.

Eine video Übersicht darüber habe ich auf YouTube hochgeladen:

Die nötigen Dateien um es selber durchzuführen und einen WebFlasher gibt es hier:



  1. Just read the header, you're my hero! This is a big deal I think as that chip is ubiquitous in chinese BT gadgets.
    As I've already sniffed the encyption keys I don't need to flash the thermometers but maybe I will be finally able to use the yeelight ceiling lamp rotary switch (YLKG08YL). I don't have any of these lamps, bought it long time ago thinking I will be able to use it with ESPHome. Coincidentally it also uses the same tslr chip. I found some scattered info about the SDK and programmer but never got around to try that. Tried playing with BT interface (first time ever) but some secret key is needed for bonding/pairing unfortunately, without lamp or any other legit device it communicates with it seemed futile. As it's just a rotary encoder over BT I think I can code custom firmware easily. 😀 Ok, time to take a look at your repo.

  2. Wow, even the Mi BLE Mesh provisioning has been cracked🥳. I've looked at this project long ago but it wasn't working.

  3. Great job with reimplementing the firmware! That must've taken a lot of reverse-engineering. I suppose I could write an ESPHome module for communicating with it.

  4. Moin,
    sehr gute Arbeit. Ich kann die Firmware sehr gut in meinem Smarthome-Projekt gebrauchen. Ich hatte die Sensioren schon auf Verdacht aufgrund des Preises und der Optik montiert. Deine Arbet ist Gold wert. Ich habe nun 8 solche Teile mit ESPhome und Home-Assitant am laufen. Good Job!
    Wenn ichim Sinne von Tests oder Bugfixes helfen kann, lass es mich wissen.

  5. Hello,
    after flashing it is not possible to connect to Mihome app. I activated "Mi like" in flasher but it doesnt help

    1. Why would you connect to mihome after flash? Flashing is for breaking the chains of mihome

  6. Thanks for creating this - very much appreciated.

    I bought 4 sensors to try this on - they all flashed pretty easily as described.

    However, for one of the sensors, I did not record the MI Token or the MI Bind Key and now I can't connect to it - is there a way around this? Many thanks.