LYWSD02MMC not showing any readings

Compatible devices
1

Hi all,
I have OMG v1.5.0 on esp32-m5atom-lite. Little LYWSD03MMC (with PVVX fw) sends data, but bigger LYWSD02MMC (with clock, hw F3_A1, fw 2.0.1_0060) sends only {id, rssi}.
Any suggestion?

Thanks

2

Hi @segeda,

The LYWSD02MMC is not yet supported, only the LYWSD02 is. As far as I know, LYWSD02MMC only send its data in encrypted advertising broadcasts. It also doesn’t seem to be compatible with ATC/PVVX firmware yet.

To confirm if the broadcasts are encrypted or not you can turn on advertisement and advanced data and then post some of the more detailed MQTT messages from the LYWSD02MMC, along with the temperature and humidity it shows when these messages were taken. We can then see if it’s possible to reverse engineer the data format, if not encrypted.

Alternatively is should be possible to get the data form LYWSD02MMC by READing its appropriate service/characteristics

3 
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416533b025d38c1a4","rssi":-59,"distance":1.01076,"servicedata":"5858e416543b025d38c1a495fb7d91090000a3dd367e","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416553b025d38c1a4","rssi":-67,"distance":2.509097,"servicedata":"4858e4165551b54dc1ad316e090000439ce498","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416553b025d38c1a4","rssi":-62,"distance":1.429824,"servicedata":"5858e416563b025d38c1a42303e2d9090000fa82dfc9","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416573b025d38c1a4","rssi":-66,"distance":2.246586,"servicedata":"4858e41657675ae7be1cf4dc0900005b61a051","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"rssi":-63,"distance":1.602966,"servicedata":"4858e4165bbb6c1958e045f90900006eff007e","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e4165b3b025d38c1a4","rssi":-66,"distance":2.246586,"servicedata":"5858e4165c3b025d38c1a4cffa94e40900006b21b0be","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e4165f3b025d38c1a4","rssi":-65,"distance":2.009448,"servicedata":"4858e4165f9e6bbc0b22a2a7090000132d8b99","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416633b025d38c1a4","rssi":-62,"distance":1.429824,"servicedata":"5858e416643b025d38c1a438403e9a0900008edc1ee3","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416653b025d38c1a4","rssi":-61,"distance":1.274439,"servicedata":"4858e41665e8acf1d23d677a0900009a7a9be3","servicedatauuid":"0xfe95"}
{"id":"A4:C1:38:5D:02:3B","mac_type":0,"adv_type":0,"manufacturerdata":"8f031058e416653b025d38c1a4","rssi":-60,"distance":1.135236,"servicedata":"5858e416663b025d38c1a4419cd4d8090000d67cdc08","servicedatauuid":"0xfe95"}

Time: 20:28
Hum: 56 %
Temp: 20.6 °C

4

Thanks. it really does look like the default firmware advertisement data is encrypted though.

So for the time being with OpenMQTTGateway it would only be possible to access the properties with the above mentioned READ command, but not through BLE advertisment data through Theengs Decoder.

Hopefully there will be an alternative firmware version ATC/PVVX for the LYWSD02MMC, like for the LYWSD03MMC, sometime soon.

5

In projects custom-components/ble_monitor, dentra/esphome-components and Bluetooth-Devices/xiaomi-ble I found support for LYWSD02MMC.
Maybe just wait :wink:

6

Correct, and in the ble_monitor supported devices list

it states

Encrypted true

for the LYWSD02MMC.

With encryption keys not being possible to store within the Theengs Decoder library itself, and more importantly not currently possible/not easily implemented to pass and store different encryption keys for all the different projects using Theengs Decoder, any device only broadcasting encrypted messages is not feasible at the moment :frowning: