We live in a world where everything is connected. One day, I wanted to know the temperature of my house when I’m outside to check if the heating regulator is working or not. Already having a bluetooth Xiaomi Mijia lywsd03mmc thermometer, I was looking for something cheap and tiny to do connect to the thermometer and do the job.
I did some research and found a chip called
ESP32. This chip has integrated bluetooth and WIFI. It is very tiny (3cmx6cm). Also, very easy to program using some known tools like arduino or esphome. Therefore, I decided to give this a try and I bought it for 4$.
- ESP32-DevKitC board : Buy here from aliexpress
- Xiaomi Mijia Thermoemter v2 with battery : Buy here from aliexpress
If you find any problem during this tutorial: Please leave a commment and I will reply very soon!
I am not a big fan of hardware programming and flashing… So I’ve looked for existing tools that configure easily ESP32 to connect to the Xiaomi mijia. ESPhome was one the easiest tool because it requires no code, but only configuration is need. ESPhome is a tool, with a set of predefined modules and configuration, that can generate the wanted code for esp32 chip. Example:
- Connect to a Xiaomi BLE thermometer
- Measure the temperature using DHT sensor
- Detect the presence of BLE tag
- Turn on/off light
In addition, ESPhome can easily add a webserver to ESP32, configure wifi, update the code Over-The-Air (OTA).
Let’s create the configuration for connecting ESP32 to the Xiaomi Mijia lywsd03mmc. ESPhome is based on yaml configuration.
esphome: name: livingroom platform: ESP32 board: esp32doit-devkit-v1 wifi: ssid: "MyWifiName" password: "MyWifiPassword" # specify address ip to use use_address: "192.168.1.20" # Enable logging logger: # Enable Home Assistant API api: # Add webserver on port 80 web_server: port: 80 # Enable update Over-The-Air ota: # Enable Bluetooth scanning for this ESP32 esp32_ble_tracker: sensor: - platform: xiaomi_lywsd03mmc mac_address: XX:XX:XX:XX:XX:XX bindkey: "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" temperature: name: "LYWSD03MMC Temperature" humidity: name: "LYWSD03MMC Humidity" battery_level: name: "LYWSD03MMC Battery Level" # Show the status of ESP32 binary_sensor: - platform: status name: "Living Room Status"
If you read at the configuration above, you can notice how basic and clear it is. Only 2 fields are to be defined :
mac_address and bindkey of the
Find Xiaomi Mijia information
In order to connect to the thermomter, we should provide its bluetooth mac address. But, the Xiaomi
LYWSD03MMC send crypted data, using a
bindkey that we should provide too.
Finding Mac Address
Find the MAC address using the
omar@mypc ~ $ bluetoothctl scan on Discovery started ... [NEW] Device XX:XX:XX:XX:XX:XX LYWSD03MMC ....
Find the bindkey
There is many ways to get a bindkey.
- The first one is to follow the ESPhome instruction. (I had some problems with Android 11 and didn’t work)
- Use a tool that I used and worked perfectly:
- On your
mobile, go to https://atc1441.github.io/TelinkFlasher.html
- Enable bluetooth
- Click on
connectat the top of page
- A list of bluetooth nearby devices will apear, click on your LYWSD03MMC device
- Once connected, click on
- Wait few seconds, and then you should see
Mi Bind Keyfilled.
- On your
Now go back to the yaml configuration and fill the
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Flash the ESP32 with the configuration above
Run ESPhome using docker
Now that we have a correct configuration, let’s flash the ESP32. Connect the chip to your computer using USB cable. I’ve used ESPhome using docker compose.
Create a directory for your project. In this directory, add the following docker-compose.yaml file. Also create a directory called
config inside it.
config directory add the
livingroom.yaml that we have defined before.
The files tree should look like this.
| myproject | -- docker-compose.yaml | -- config | |-- livingroom.yaml
Here is the docker-compose.yaml file.
# docker-compose.yaml file version: "3.5" services: esphome: image: esphome/esphome container_name: esphome ports: - 6052:6052 volumes: # HERE we will add the livingroom.yaml - ./config:/config network_mode: host # Important to flash using USB devices: - /dev/ttyUSB0:/dev/ttyUSB0
Run the ESPhome using the command
docker-compose up -d
Flash the configuration
Now that your ESPHome is running, go to http://localhost:6052. You should see an interface with
livingroom item appearing.
On the top right, click on the select menu and choose
USB for the first flash.
Then, click on
Validate to check that your structure is ok and
Upload to run the flash.
If all is successful, you will see a log that looks like the photo above. You can read the logs and wait until you see that humidity and temperature.
Otherwise, go to http://livingroom.local/ to see a webpage with the requested information.
UPDATE Home asssistant integration
I have wrote a new article on how to install home assistant and how to configure it
If this tutorial was helpful, please leave a comment and tell me your opinion. In the next tutorial I will show you how to access the temperature data when you are outdoor.
I wish you good luck with ESP32!