无法读取Beurer BF950蓝牙体重秤体重测量特征值的问题求助

开发者阿泽

2026-4-14

我手头有一台支持BLE的Beurer BF950体重秤，现在遇到了个棘手的问题：没法从设备上读取体重数据。厂商给了一份包含UUID的Excel表，我照着写了代码，但体重测量的回调函数根本不会被触发——虽然能成功订阅服务，但就是一直等不到数据。奇怪的是，用官方APP就能正常获取体重，说明设备本身是能正常传输数据的。

先给大家看看我最开始写的代码：

import asyncio
from bleak import BleakClient
from struct import unpack

BEURER_BF950_ADDRESS = "5C:CA:D3:F8:1C:C6"
WEIGHT_SCALE_SERVICE_UUID = "0000181d-0000-1000-8000-00805f9b34fb"
WEIGHT_MEASUREMENT_CHARACTERISTIC_UUID = "00002a9d-0000-1000-8000-00805f9b34fb"

async def connect_and_read_weight(address):
    try:
        async with BleakClient(address) as client:
            print(f"Connected: {client.is_connected}")

            await client.start_notify(WEIGHT_MEASUREMENT_CHARACTERISTIC_UUID, weight_measurement_callback)

            print("Please step on the scale...")
            await asyncio.sleep(30)  

            await client.stop_notify(WEIGHT_MEASUREMENT_CHARACTERISTIC_UUID)

    except Exception as e:
        print(f"Error: {e}")

def weight_measurement_callback(sender, data):
    # print("here")
    flags = data[0]
    weight = unpack("<H", data[1:3])[0] * 0.005  

    print(f"Weight: {weight:.2f} kg")

async def main():
    print("Attempting to connect and read weight...")
    await connect_and_read_weight(BEURER_BF950_ADDRESS)
    print("Operation completed.")

asyncio.run(main())

这段代码里，我能成功连接设备，也执行了start_notify，但weight_measurement_callback就是没反应——哪怕我站到秤上也没用。

不过我确认设备连接是正常的，因为用下面这段代码能读取到设备的静态特征值，比如电池电量、厂商信息这些：

import asyncio
from bleak import BleakClient

BEURER_BF950_ADDRESS = "5C:CA:D3:F8:1C:C6"

# List of characteristics to read
CHARACTERISTICS_TO_READ = [
    ("00002a9e-0000-1000-8000-00805f9b34fb", "Weight Scale Feature"),
    ("00002a19-0000-1000-8000-00805f9b34fb", "Battery Level"),
    ("00002a29-0000-1000-8000-00805f9b34fb", "Manufacturer Name"),
    ("00002a24-0000-1000-8000-00805f9b34fb", "Model Number"),
    ("00002a26-0000-1000-8000-00805f9b34fb", "Firmware Revision"),
    ("00002a27-0000-1000-8000-00805f9b34fb", "Hardware Revision"),
    ("00002a28-0000-1000-8000-00805f9b34fb", "Software Revision"),
    ("00002a23-0000-1000-8000-00805f9b34fb", "System ID"),
    ("0000000b-0000-1000-8000-00805f9b34fb", "Custom Characteristic (Reference Weight/BF)"),
    ("00000000-0000-1000-8000-00805f9b34fb", "Custom Characteristic (Scale Setting)"),
]

async def read_characteristics(address):
    try:
        async with BleakClient(address) as client:
            print(f"Connected: {client.is_connected}")

            for uuid, name in CHARACTERISTICS_TO_READ:
                try:
                    value = await client.read_gatt_char(uuid)
                    print(f"{name} ({uuid}):")
                    print(f"  Raw: {value.hex()}")
                    if name == "Battery Level":
                        print(f"  Parsed: {value[0]}%")
                    elif name == "Manufacturer Name" or name == "Model Number":
                        print(f"  Parsed: {value.decode('utf-8')}")
                    else:
                        print(f"  Parsed: {value}")
                except Exception as e:
                    print(f"Error reading {name} ({uuid}): {e}")

    except Exception as e:
        print(f"Connection error: {e}")

async def main():
    print("Attempting to connect and read characteristics...")
    await read_characteristics(BEURER_BF950_ADDRESS)
    print("Operation completed.")

asyncio.run(main())

后来我还试了用自定义服务UUID，加上触发测量的特征，还用asyncio.Event来等待数据，但还是没用：

import asyncio
from bleak import BleakClient
from struct import unpack

BEURER_BF950_ADDRESS = "5C:CA:D3:F8:1C:C6"
CUSTOM_SERVICE_UUID = "0000ffff-0000-1000-8000-00805f9b34fb"
TAKE_MEASUREMENT_CHARACTERISTIC_UUID = "00000006-0000-1000-8000-00805f9b34fb"
MEASUREMENT_NOTIFY_CHARACTERISTIC_UUID = "00000007-0000-1000-8000-00805f9b34fb"

weight_received = asyncio.Event()

async def connect_and_read_weight(address):
    try:
        async with BleakClient(address) as client:
            print(f"Connected: {client.is_connected}")

            print("Enabling notifications for custom measurement characteristic...")
            await client.start_notify(MEASUREMENT_NOTIFY_CHARACTERISTIC_UUID, measurement_callback)

            print("Triggering measurement...")
            await client.write_gatt_char(TAKE_MEASUREMENT_CHARACTERISTIC_UUID, b'\x00')

            print("Please step on the scale...")
            await asyncio.wait_for(weight_received.wait(), timeout=60.0)

            print("Disabling notifications...")
            await client.stop_notify(MEASUREMENT_NOTIFY_CHARACTERISTIC_UUID)

    except asyncio.TimeoutError:
        print("Timeout: No measurement received within 60 seconds.")
    except Exception as e:
        print(f"Error: {e}")

def measurement_callback(sender, data):
    print(f"Received data: {data.hex()}")
    try:
        # The exact data format may vary, this is a guess based on common formats
        if len(data) >= 2:
            weight = unpack("<H", data[:2])[0] * 0.1  # Assuming weight is first 2 bytes, in 0.1 kg units
            print(f"Weight: {weight:.1f} kg")
            weight_received.set()
        else:
            print("Received data is too short to contain a weight measurement")
    except Exception as e:
        print(f"Error parsing data: {e}")

async def main():
    print("Attempting to connect and read weight...")
    await connect_and_read_weight(BEURER_BF950_ADDRESS)
    print("Operation completed.")

asyncio.run(main())

这段代码最后只会超时，measurement_callback也没被触发过。

有没有大佬能帮我看看问题出在哪？是不是我漏了什么步骤？比如是不是需要先写某个特征值来唤醒秤的测量模式？或者UUID用错了？毕竟官方APP能正常工作，肯定是我代码里有没考虑到的地方。

备注：内容来源于stack exchange，提问作者uzair khan