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Xiaomi-Bluetooth-Digital-Thermometer

Last month I brought a bundle of 3 bluetooth thermometer from AliExpress.

I made this repo to kept the details about how to connect and monitor the devices from a Linux box.

TL;DR;

Searchin for the devices

The device name is LYWSD03MMC in my case

% sudo hcitool lescan
A4:C1:38:XX:XX:XX LYWSD03MMC
A4:C1:38:XX:XX:XX LYWSD03MMC
A4:C1:38:XX:XX:XX LYWSD03MMC

Connecting to the device

Using gatttool you will be able to connect and enable the notifications.

First start gatttool in interactive mode to access the prompt

gatttool -b a4:c1:38:XX:XX:XX  -I
[a4:c1:38:XX:XX:XX][LE]>

The type the following commands

[a4:c1:38:XX:XX:XX][LE]>connect
Attempting to connect to a4:c1:38:XX:XX:XX
Connection successful

Now enable the notifications to get the measured values:

[a4:c1:38:XX:XX:XX][LE]>char-write-req 0x0038 0100
Characteristic value was written successfully

After this command notification should start to appears every 1 second

Notification handle = 0x0036 value: 4d 07 3d 99 0b
Notification handle = 0x0036 value: 4d 07 3d 99 0b
Notification handle = 0x0036 value: 4e 07 3d 99 0b
Notification handle = 0x0036 value: 4e 07 3d 99 0b
Notification handle = 0x0036 value: 50 07 3d 99 0b
Notification handle = 0x0036 value: 4f 07 3d 99 0b
Notification handle = 0x0036 value: 4d 07 3d 99 0b
Notification handle = 0x0036 value: 4c 07 3d 99 0b
Notification handle = 0x0036 value: 4e 07 3d 99 0b
Notification handle = 0x0036 value: 4b 07 3d 99 0b

Decoding the values

4b 07 3d 99 0b
----- --
 \     \-Humidity in % 0x3D = 61%
  \_ Temperature in Hex (0x074B = 1867) 1867 / 100 = 18.67