How to collect Temp and Humidity from XIAOMI clock with out MI HOME account - RASPBERRY PI

LYWSD02MMC

LYWSDCGQ/01ZM

LYWSD03MMC

GATTTOOL command

As a conclusion the gatttool command to be used is :

gatttool --device="MAC Addr" --char-write-req -a 0x004c -n 0100 --listen
Characteristic value was written successfully
Notification handle = 0x004b value: c3 0a 36
Notification handle = 0x004b value: c6 0a 36

For the model: LYWSD03MMC

gatttool --device="MAC Addr" --char-write-req -a 0x0038 -n 0100 --listen

Value conversions

The temperature is c3 0a (little endian) => 0x0aC3(hexa) is 2755 (decimal) => 27°55 Celcius
The Humidity is 36 => 0x36(hexa) is 54(decimal) => 54% humidity.

#Some informations about the approach to track and identification of the attributes: 1- BLE Characteristic identification To look for Temperature & Humidity characteristic - Using BLE Scanner.
With the "Characteristic" can be identified. In the case of LYWSD02MMC the UUID is ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6. 2- BLE communication tracking On one terminal run the "hcidump -X" to dump the BLE communication. 3- Turn on the notification On a second terminal run "bluetoothctl"
Run "scan on" to detect and identify the MAC of the devices
Run "connect " to connect to the device. A list of characteristic will be displayed. Identify the attribute wit the appropriate UUID (ebe0ccc1-7a0a-4b0c-8a1a-6ff2997da3a6) Run "select-attribute /org/bluez/hci0/dev_E7_2E_00_80_99_07/service003c/char004a"

Turn the notification on "notify on"

Check on the "hcidump" terminal - to identify the handle.

ACL data: handle 64 flags 0x00 dlen 9
ATT: Write req (0x12)
handle 0x004c value 0x01 0x00
ACL data: handle 64 flags 0x02 dlen 5
ATT: Write resp (0x13)
HCI Event: Number of Completed Packets (0x13) plen 5
handle 64 packets 1

In our case we did see that the handle "0x004c" is used.