How to use ble_monitor with Xiaomi Body Composition Scale S400 correctly without HA

[RobertWojtowicz]

Hi,

Looking for help on how to make a simple solution to pull data from a scale.
I partially covered the topic in this thread: Bluetooth-Devices/xiaomi-ble#158

I was able to successfully download the ble key with the solution https://github.com/PiotrMachowski/Xiaomi-cloud-tokens-extractor

I understand that now I need to connect to the scale and download the encrypted data.
Then decrypt the data and use a parser (xiaomi-ble or ble_monitor?) to extract the weight and impedance.

I would very much appreciate help on how to do this as simply as possible without HA.

BR,
Robert

[Ernst79]

No need to connect to the scale, just passively listen to the ble data with e.g bleak. Filter the data on the xiaomi uuid (95FE).

You can have a look here for an example, but note that the bleparser is way behind the parser in this integration and does not have support for your scale yet. It is basically a copy of this integration with some examples how to use it manually. https://github.com/Ernst79/bleparser

[RobertWojtowicz]

Hi @Ernst79,

I already tried to parse with UUID: Service Data 0000fe95-0000-1000-8000-00805f9b34fb, but the data is too short and does not contain measurement data, I return and something like this: 1059d53b38b0a75dacea1c (Encrypted data).

Decryption attempt:

SensorUpdate(title='Body Composition Scale A7B0 (MJTZC01YM)', devices={None: SensorDeviceInfo(name='Body Composition Scale A7B0', model='MJTZC01YM', manufacturer='Xiaomi', sw_version=None, hw_version=None)}, entity_descriptions={DeviceKey(key='signal_strength', device_id=None): SensorDescription(device_key=DeviceKey(key='signal_strength', device_id=None), device_class=<SensorDeviceClass.SIGNAL_STRENGTH: 'signal_strength'>, native_unit_of_measurement=<Units.SIGNAL_STRENGTH_DECIBELS_MILLIWATT: 'dBm'>)}, entity_values={DeviceKey(key='signal_strength', device_id=None): SensorValue(device_key=DeviceKey(key='signal_strength', device_id=None), name='Signal Strength', native_value=-76)}, binary_entity_descriptions={}, binary_entity_values={}, events={})
[1C:EA:AC:5D:A7:B0] RSSI: -78  DATA: 1059d53b38b0a75dacea1c

BR,
Robert

[RobertWojtowicz]

Hi, @Ernst79,
As it tries to download data and decrypt and parse it:

import asyncio
from bleak import BleakScanner
from xiaomi_ble.parser import XiaomiBluetoothDeviceData
from bluetooth_sensor_state_data import BluetoothServiceInfo

BINDKEY = "adddba28d5c05f005fe21677b5a58e1e"
TARGET_MAC = "1C:EA:AC:5D:A7:B0"

parser = XiaomiBluetoothDeviceData(bindkey=bytes.fromhex(BINDKEY))

def detection_callback(device, advertisement_data):
    if device.address.upper() != TARGET_MAC:
        return

    service_data = advertisement_data.service_data.get("0000fe95-0000-1000-8000-00805f9b34fb")
    if not service_data:
        return

    print(f"[{device.address}] RSSI: {advertisement_data.rssi}  DATA: {service_data.hex()}")

    service_info = BluetoothServiceInfo(
        name=device.name,
        address=device.address,
        rssi=advertisement_data.rssi,
        manufacturer_data=advertisement_data.manufacturer_data,
        service_data=advertisement_data.service_data,
        service_uuids=advertisement_data.service_uuids,
        source=device.address,
    )

    if parser.supported(service_info):
        update = parser.update(service_info)
        if update:
            print(update)

async def main():
    scanner = BleakScanner(detection_callback=detection_callback)
    await scanner.start()
    await asyncio.sleep(30)
    await scanner.stop()

if __name__ == "__main__":
    asyncio.run(main())

BR,
Robert

[RobertWojtowicz]

Hi,
@Ernst79

ok data collection works with this script as for a while I turn on the Xiaomi Home app, which connects to the scale.
Then it works without the app for a while, and then it stops until the app is triggered again:

[1C:EA:AC:5D:A7:B0] RSSI: -90  DATA: 1059d53ba2b0a75dacea1c
SensorUpdate(title='Body Composition Scale A7B0 (MJTZC01YM)', devices={None: SensorDeviceInfo(name='Body Composition Scale A7B0', model='MJTZC01YM', manufacturer='Xiaomi', sw_version='Xiaomi (MiBeacon V5 encrypted)', hw_version=None)}, entity_descriptions={DeviceKey(key='signal_strength', device_id=None): SensorDescription(device_key=DeviceKey(key='signal_strength', device_id=None), device_class=<SensorDeviceClass.SIGNAL_STRENGTH: 'signal_strength'>, native_unit_of_measurement=<Units.SIGNAL_STRENGTH_DECIBELS_MILLIWATT: 'dBm'>), DeviceKey(key='mass', device_id=None): SensorDescription(device_key=DeviceKey(key='mass', device_id=None), device_class=<SensorDeviceClass.MASS: 'mass'>, native_unit_of_measurement=<Units.MASS_KILOGRAMS: 'kg'>), DeviceKey(key=<ExtendedSensorDeviceClass.HEART_RATE: 'heart_rate'>, device_id=None): SensorDescription(device_key=DeviceKey(key=<ExtendedSensorDeviceClass.HEART_RATE: 'heart_rate'>, device_id=None), device_class=<ExtendedSensorDeviceClass.HEART_RATE: 'heart_rate'>, native_unit_of_measurement='bpm'), DeviceKey(key='impedance', device_id=None): SensorDescription(device_key=DeviceKey(key='impedance', device_id=None), device_class=<SensorDeviceClass.IMPEDANCE: 'impedance'>, native_unit_of_measurement=<Units.OHM: 'ohm'>), DeviceKey(key=<ExtendedSensorDeviceClass.PROFILE_ID: 'profile_id'>, device_id=None): SensorDescription(device_key=DeviceKey(key=<ExtendedSensorDeviceClass.PROFILE_ID: 'profile_id'>, device_id=None), device_class=<ExtendedSensorDeviceClass.PROFILE_ID: 'profile_id'>, native_unit_of_measurement=None)}, entity_values={DeviceKey(key='signal_strength', device_id=None): SensorValue(device_key=DeviceKey(key='signal_strength', device_id=None), name='Signal Strength', native_value=-90), DeviceKey(key='mass', device_id=None): SensorValue(device_key=DeviceKey(key='mass', device_id=None), name='Mass', native_value=59.0), DeviceKey(key=<ExtendedSensorDeviceClass.HEART_RATE: 'heart_rate'>, device_id=None): SensorValue(device_key=DeviceKey(key=<ExtendedSensorDeviceClass.HEART_RATE: 'heart_rate'>, device_id=None), name='Heart Rate', native_value=73), DeviceKey(key='impedance', device_id=None): SensorValue(device_key=DeviceKey(key='impedance', device_id=None), name='Impedance', native_value=564.4), DeviceKey(key=<ExtendedSensorDeviceClass.PROFILE_ID: 'profile_id'>, device_id=None): SensorValue(device_key=DeviceKey(key=<ExtendedSensorDeviceClass.PROFILE_ID: 'profile_id'>, device_id=None), name='Profile ID', native_value=1)}, binary_entity_descriptions={}, binary_entity_values={}, events={})

BR,
Robert

[Ernst79]

Hmmm, that is not a thing I can help you with. Most likely just the behavior of the scale to safe battery. The s400 scale is giving more people trouble. I don’t have it myself, so can’t test it.

[RobertWojtowicz]

Hi,
@Ernst79

Sure, I understand, the important thing is that I have a track and can already extract this data, the question is still where to look for the date and time of weighing because as you can see, unfortunately, it is not in this data.

BR,
Robert

[Ernst79]

Date and time are not broadcasted, you will have to do that yourself. I assume it just sends out the current mass, or the latest measured mass.

Normally, I would expect that the scale starts sending data when turning it on. Or when the measurement is finished.

[RobertWojtowicz]

Hi,
@Ernst79

I wonder how HA does it so that this data is always acquired without any problem ?
I don't know who to contact to help me solve the problem.

BR,
Robert

[Ernst79]

If you don’t receive the data, neither can HA. Perhaps enabling active scan can help (in stead op passive scan).

I assume you have added it to MiHome. This is needed to make it broadcast.

[Ernst79]

Active scan can be set in bleak with this parameter https://bleak.readthedocs.io/en/latest/api/scanner.html

scanning_mode – Set to "passive" to avoid the "active" scanning mode. Passive scanning is not supported on macOS! Will raise BleakError if set to "passive" on macOS.

Seems to be the default already.

[RobertWojtowicz]

Thanks @Ernst79,

I'll check it out, it's a pity that there is nowhere to read how HA does it, because people would probably complain that once it works and once it doesn't :)

BR,
Robert