Xiaomi's Bluetooth Thermometers: affordable, sleek, and hackable?

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A digital illustration of a red, analogue thermometer.

Xiaomi's Bluetooth thermometers and hygrometers offer a stylish and budget-friendly choice for monitoring temperature and humidity. Their seamless integration with ESPHome thorugh the versitile ESP 32 allows users to transmit data directly to Home Assistant, bypassing the need for any additional apps. Interestingly, tech enthusiasts have unearthed the potential for hacking these devices, unlocking new functionalities.


A Wolf in Sheep's Clothing

For those considering purchasing one of these thermometers with the intention of installing custom firmware, caution is advised. It is crucial to verify the model, as there exists a look-alike model, CGG1H by Qingping, which is incompatible with firmware flashing.

Installing Custom Firmware on Xiaomi Bluetooth Thermometers

Embarking on the journey to install custom firmware on your Xiaomi thermometer and hygrometer is surprisingly straightforward. Utilize the Telink Flasher for Mi Thermostat tool for a smooth process. Your browser, be it Google Chrome, Microsoft Edge, or Opera, will recognize the device without requiring pairing with your computer.

Screenshot of the 'Telink Flasher for Mi Thermostat,' featuring buttons for 'Connect,' 'Get Advertising MAC', and 'Reconnect.' There is a checkbox option to 'Hide unknown' devices, which is checked. Below is a field labelled 'BLE device name prefix filter(s)' containing the text 'LYWSD03,ATC.' At the bottom, the status message reads 'waiting for you to connect a device.

After connecting your Xiaomi thermometer, activate the decryption key process with the Do Activation button.

The installation of custom firmware is then just a few steps away, and reverting to the original firmware is always an option for those who prefer it.

A screenshot of the Chrome browser showing a popup asking the user to pair with a Xiaomi thermometer.
Xiaomi Bluetooth Thermometer 01

Benefits of Custom Firmware for Xiaomi Bluetooth Thermometers

Custom firmware enhances Xiaomi Bluetooth thermometers with several features. It allows for calibration of temperature and humidity readings by setting offsets, using a reliable sensor for precise measurements.

Additionally, the firmware offers customization options, including multiple display pages and data fields like temperature, humidity, battery percentage, and current time. The device's smiley face icon can also be programmed to reflect temperature and humidity levels, with customizable 'happy zones.' For further customization options, refer to the GitHub repository.

Potential Hardware Upgrades for Xiaomi Bluetooth Thermometers

In line with the device's hackable nature, hardware modifications can enhance its functionality. A reed switch can be soldered onto the board, transforming the thermometer into a window or door sensor. Some users have even modified their devices with rechargeable batteries and solar panels, promoting a sustainable approach.

A portrait photo oif Liam Alexander Colman, the author, creator, and owner of Home Assistant Guide wearing a suit.

About Liam Alexander Colman

is an experienced Home Assistant user who has been utilizing the platform for a variety of projects over an extended period. His journey began with a Raspberry Pi, which quickly grew to three Raspberry Pis and eventually a full-fledged server. Liam's current operating system of choice is Unraid, with Home Assistant comfortably running in a Docker container.
With a deep understanding of the intricacies of Home Assistant, Liam has an impressive setup, consisting of various Zigbee devices, and seamless integrations with existing products such as his Android TV box. For those interested in learning more about Liam's experience with Home Assistant, he shares his insights on how he first started using the platform and his subsequent journey.

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