# How 2 Flashing ATC Firmware on Xiaomi Temperature Humidity sensor (LYWSD03MMC)

> This article will take you though the process of flashing custom ATC firmware on to the Xiaomi Temperature and Humidity sensor, model LYWSD03MMC. Works with Hardware version `B1.6` released at March of 2025. [name=Ender][time=Saturday, December 20, 2025]

[TOC]

## Flashing the Firmware

1. Adopt your sensor within the Xiaomi Home App
1. Get the tokens by running [Xiaomi Cloud Tokens Extractor](https://github.com/PiotrMachowski/Xiaomi-cloud-tokens-extractor) and follow the on screen instructions
2. Open [TelinkMiFlasher](https://pvvx.github.io/ATC_MiThermometer/TelinkMiFlasher.html) in Chrome browser (Brave & Firefox browser is not supported)
3. Click the `Connect` button and select the Xiaomi Temperature Humidity sensor from the dropdown list (default name is `LYWSD03MMC`)
4. Input the Device known id, Mi Token and Mi Bind Key obtained from the Xiaomi Cloud Tokens Extractor then click the `Login` button
5. Select the `Original_OTA_Xiaomi_LYWSD03MMC_v2.1.1_0159c.bin` firmware file then click the `Start Flashing` button
6. After flashing is completed, click the `Reconnect` button to reconnect to the device
7. Input the Device known id, Mi Token and Mi Bind Key obtained from the Xiaomi Cloud Tokens Extractor then click the `Login` button
8. Select the `Custom Firmware: ATC_v54.bin` firmware file then click the `Start Flashing` button
9. After flashing is completed, click the `Reconnect` button and you should see the custom parmeters page

And now you'll be able to add the device to Home Assistant using the BTHome integration, the Home Assistant should automatically discover the sensor.

## Connect to Home Assistant
1. Ensure the `Advertising type` is set to `BTHome` in [TelinkMiFlasher](https://pvvx.github.io/ATC_MiThermometer/TelinkMiFlasher.html)
2. Add the BTHome integration to your Home Assistant instance. [Click to Add](https://my.home-assistant.io/redirect/config_flow_start?domain=bthome)

The BTHome integration will automatically discover your devices and add them to your Home Assistant. If not, ensure the sensor is on and the Bluetooth integration is enabled in the Home Assistant instances.

## Links

- TelinkMiFlasher - https://pvvx.github.io/ATC_MiThermometer/TelinkMiFlasher.html
- Xiaomi Cloud Tokens Extractor - https://github.com/PiotrMachowski/Xiaomi-cloud-tokens-extractor
- ATC_MiThermometer - https://github.com/pvvx/ATC_MiThermometer
- TelinkMiFlasher stpes - https://github.com/pvvx/ATC_MiThermometer/issues/602#issuecomment-2590913442

###### tags: Xiaomi, Sensor, ATC, Custom Firmware, Home Assistant, BTHome, BLE