Xiaomi is known for offering some stylish and wallet-friendly Bluetooth thermometers and hygrometers. They have a delightful compatibility with ESPHome, enabling users to pump the data directly into Home Assistant sans any apps thanks to an ESP32. However, tech enthusiasts have discovered that these devices can also be hacked – surprise, surprise!

A wolf in sheep's clothing
Just a quick heads up for those planning to grab one of these thermometers intending to instal the custom firmware, be sure to check the model. There's a doppelgänger out there named CGG1H from Qingping that looks identical but doesn't play nice with flashing.
How to install custom firmware on Xiaomi Bluetooth thermometers
So, you've decided to take the plunge and install the custom firmware on your Xiaomi thermometers and hygrometer. The process is as smooth as butter! Simply open the Telink Flasher for Mi Thermostat tool, wait for your browser to spot the device, and hit connect.


No need to fuss about pairing the device with your computer. Let Google Chrome, Microsoft Edge, or Opera take the wheel!
After your Xiaomi thermometer is connected, hit the Do Activation button to kickstart the decryption key process.
And voilà! You're now ready to install the custom firmware. If you're feeling nostalgic, you can also revert to the original firmware anytime.

The perks of custom firmware for Xiaomi Bluetooth Thermometers
The custom firmware for Xiaomi's Bluetooth thermometers packs a punch. You can adjust the temperature and humidity readings by setting an offset. If you have a trusted sensor, you can use it to calibrate the Xiaomi device for precise measurements.
But the fun doesn't stop there. The firmware lets you configure multiple pages and toggle between varied data fields like temperature/humidity, battery percentage, and current time – just by ticking a few boxes.
The cute little smiley on the device isn't just for show. You can either choose to always have a cheerful smiley or set it to react to the current temperature and humidity. You can even customize the 'happy zone' to your liking. For more configuration possibilities, check out the GitHub repository.
Potential hardware upgrades for Xiaomi Bluetooth Thermometers
In a twist that shocks no one, there are a handful of hardware tweaks that can soup up your Xiaomi thermometer. You can solder a reed switch onto the board, turning it into a window/door sensor. Some crafty folks have even equipped their thermometers with rechargeable batteries and solar panels – talk about going green!