使用 bluepy 从通知属性中获取值

Question

我正在用 ubuntu 在树莓派 4 上创建一个 python 程序。 该程序必须连接到指定的 BLE 设备并获取特定 NOTIFY 属性的值。

这些都是 BLE 设备的服务和功能。 用bluepy库扫描得到

Service UUID: 00001800-0000-1000-8000-00805f9b34fb
     -> Characteristic UUID: 00002a00-0000-1000-8000-00805f9b34fb
        Characteristic handle: 3
        Characteristic properties: READ 
        Value: b''
     -> Characteristic UUID: 00002a01-0000-1000-8000-00805f9b34fb
        Characteristic handle: 5
        Characteristic properties: READ 
        Value: b'\x00\x00'
     -> Characteristic UUID: 00002a04-0000-1000-8000-00805f9b34fb
        Characteristic handle: 7
        Characteristic properties: READ 
        Value: b'\xff\xff\xff\xff\x00\x00\xff\xff'
Service UUID: 00001801-0000-1000-8000-00805f9b34fb
     -> Characteristic UUID: 00002a05-0000-1000-8000-00805f9b34fb
        Characteristic handle: 10
        Characteristic properties: INDICATE 
Service UUID: 00001523-1212-efde-1523-785feabcd123
     -> Characteristic UUID: 00001027-1212-efde-1523-785feabcd123
        Characteristic handle: 13
        Characteristic properties: READ WRITE 
     -> Characteristic UUID: 00001011-1212-efde-1523-785feabcd123
        Characteristic handle: 15
        Characteristic properties: NOTIFY 
Service UUID: 0000180d-0000-1000-8000-00805f9b34fb
     -> Characteristic UUID: 00002a37-0000-1000-8000-00805f9b34fb
        Characteristic handle: 19
        Characteristic properties: NOTIFY 

我感兴趣的服务是最后两个 UUID，BLE 扫描器应用程序也证实了这一点。

为了获得通知的价值，我使用以下代码

def threadWrite(characteristic, peripheral):
    # is the Characteristic UUID: 00001027-1212-efde-1523-785feabcd123
    characteristic.write(b"reset\n")
    time.sleep(1)
    characteristic.write(b"read ppg 4\n")
    time.sleep(1)

    peripheral.setDelegate(classes.MyDelegate())
    svc = peripheral.getServiceByUUID("00001523-1212-efde-1523-785feabcd123")
    ch = svc.getCharacteristics("00001011-1212-efde-1523-785feabcd123")[0]
    ch_cccd = ch.getDescriptors(forUUID=0x2902)[0]
    ch_cccd.write(b"\0x1\x00")

    while True:
        if peripheral.waitForNotifications(1.0):
            # handleNotification() was called
            continue
        print("Waiting...")

//different module
class MyDelegate(btle.DefaultDelegate):
    def __init__(self):
        btle.DefaultDelegate.__init__(self)

    def handleNotification(self, cHandle, data):
        print ("Notification received: handle =", cHandle, "; Raw data =", binascii.b2a_hex(data))

我检查了我用 peripheral.writeCharacteristic 发送的命令，它们实际上到达了设备，因为扫描开始了； 即使连接到 BLE 扫描仪，我也会看到 NOTIFY 值更新。

问题是我只得到最后一个服务的通知值：0000180d-0000-1000-8000-00805f9b34fb - 句柄：19。相反，我需要特征 UUID 的通知：00001011-1212-efde-1523-785feabcd123 - 句柄: 15

我哪里做错了？

Answer 1

您似乎没有启用通知。 这是通过将1 （作为 int16 小端值）发送到 UUID 为0x2902的描述符（这是标准的蓝牙 UUID，因此也可以完整地写为00002902-0000-1000-8000-00805f9b34fb ）来完成的。

所以你的代码的开头需要看起来像：

    peripheral.setDelegate(classes.MyDelegate(ch.getHandle())
    svc = peripheral.getServiceByUUID("00001523-1212-efde-1523-785feabcd123")
    ch = svc.getCharacteristics("00001011-1212-efde-1523-785feabcd123")[0]
    ch_cccd = ch.getDescriptors(forUUID=0x2902)[0]
    ch_cccd.write(b"\0x1\x00")