BLE 使用 gatttool 或 bluepy 订阅通知

Question

我正在使用 bluepy 编写一个程序，用于侦听蓝牙设备发送的特征。我也可以使用任何库或语言，唯一的限制是在 Linux 上运行而不是在移动环境中运行（似乎只在移动设备中广泛使用，没有人在桌面上使用 BLE）。 使用 bluepy 我注册了委托，并在尝试注册通知后调用write('\x01\x00')，如蓝牙 rfc 中所述。 但它不起作用，收到任何有关该特征的通知。 也许我在写订阅消息时是错误的。 我写的小sn-p有错误吗？非常感谢。

class MyDelegate(btle.DefaultDelegate):

    def __init__(self, hndl):
        btle.DefaultDelegate.__init__(self)
   self.hndl=hndl;

   def handleNotification(self, cHandle, data):
   if (cHandle==self.hndl):
            val = binascii.b2a_hex(data)
            val = binascii.unhexlify(val)
            val = struct.unpack('f', val)[0]
            print str(val) + " deg C"


p = btle.Peripheral("xx:xx:xx:xx", "random")

try:
   srvs = (p.getServices());
   chs=srvs[2].getCharacteristics();
   ch=chs[1];
   print(str(ch)+str(ch.propertiesToString()));
   p.setDelegate(MyDelegate(ch.getHandle()));
   # Setup to turn notifications on, e.g.
   ch.write("\x01\x00");

   # Main loop --------
   while True:
      if p.waitForNotifications(1.0):
      continue

      print "Waiting..."
finally:
    p.disconnect();

Answer 1

bluepy 类文档和示例很疯狂，而且不完整。要了解更多详情，请查看 bluepy source（它并不大且易于阅读）

但是，作为起点，您可以使用此通知代码示例，使用心率服务（在 bluepy 1.3.0 上测试）

不要忘记在 Peripheral 中将设备 MAC 替换为您自己的！

from bluepy import btle
from bluepy.btle import AssignedNumbers

import binascii

class MyDelegate(btle.DefaultDelegate):
    def __init__(self, handle):
        btle.DefaultDelegate.__init__(self)
        self.handle = handle
        print "Created delegate for handle", self.handle
        # ... more initialise here

    def handleNotification(self, cHandle, data):
        if(cHandle == self.handle):
            print "handleNotification for handle: ", cHandle, "; Raw data: ", binascii.b2a_hex(data)
            #Found somewhere. Not tested is this working, but leave here as decode example
            #val = binascii.b2a_hex(data)
            #val = binascii.unhexlify(val)
            #val = struct.unpack('f', val)[0]
            #print str(val) + " deg C"

print "Connecting..."
dev = btle.Peripheral("c8:2b:96:a3:d4:76")

try:
    print "Device services list:"
    for svc in dev.services:
        print str(svc)


    HRService = dev.getServiceByUUID(AssignedNumbers.heartRate)
    print "HRService", HRService

    print "HRService characteristics list: "
    for char in HRService.getCharacteristics():
        print "HRService char[", char.getHandle(), "]: ", char

    HRMeasurementChar = HRService.getCharacteristics(AssignedNumbers.heart_rate_measurement)[0] #Notice! Check is characteristic found before usage in production code!
    print "HRMeasurementChar", HRMeasurementChar, HRMeasurementChar.propertiesToString();

    # Assign delegate to target characteristic
    dev.setDelegate(MyDelegate(HRMeasurementChar.getHandle()));

    # We need to write into org.bluetooth.descriptor.gatt.client_characteristic_configuration descriptor to enabe notifications
    # to do so, we must get this descriptor from characteristic first
    # more details you can find in bluepy source (def getDescriptors(self, forUUID=None, hndEnd=0xFFFF))
    desc = HRMeasurementChar.getDescriptors(AssignedNumbers.client_characteristic_configuration);
    print "desc", desc

    print "Writing \"notification\" flag to descriptor with handle: ", desc[0].handle
    dev.writeCharacteristic(desc[0].handle, b"\x01\x00")# Notice! Do not use [0] in production. Check is descriptor found first!

    print "Waiting for notifications..."

    while True:
        if dev.waitForNotifications(1.0):
            # handleNotification() was called
            continue

finally:
    dev.disconnect();

Answer 2

让我感到困惑的是https://ianharvey.github.io/bluepy-doc/notifications.html 启用通知的部分在 cmets 中，所以我觉得它不是必须的。

对我来说，最低限度（假设你已经知道 MAC 地址并且你包含了所有内容并声明了 Delegateclass）是

p1 = Peripheral(<MAC>)
ch1 = p1.getCharacteristics()[3]
p1.setDelegate(MyDelegate())
p1.writeCharacteristic(ch1.valHandle + 1, b"\x01\x00")

请注意，我已经知道我想从特征#3 获取通知。 另外，如果没有 "\x0\x00" 前面的 'b'-bytesprefix，它对我不起作用。

Answer 3

我自己也在为此苦苦挣扎，而 jgrant 的评论确实很有帮助。我想分享我的解决方案，如果它可以帮助任何人。

请注意，我需要指示，因此需要 x02 而不是 x01。

如果可以使用 bluepy 读取描述符，我会这样做，但它似乎不起作用（bluepy v 1.0.5）。服务类中的方法好像丢失了，外围类中的方法在我尝试使用时卡住了。

from bluepy import btle

class MyDelegate(btle.DefaultDelegate):
    def __init__(self):
        btle.DefaultDelegate.__init__(self)

    def handleNotification(self, cHandle, data):
        print("A notification was received: %s" %data)


p = btle.Peripheral(<MAC ADDRESS>, btle.ADDR_TYPE_RANDOM)
p.setDelegate( MyDelegate() )

# Setup to turn notifications on, e.g.
svc = p.getServiceByUUID( <UUID> )
ch = svc.getCharacteristics()[0]
print(ch.valHandle)

p.writeCharacteristic(ch.valHandle+1, "\x02\x00")

while True:
    if p.waitForNotifications(1.0):
        # handleNotification() was called
        continue

    print("Waiting...")
    # Perhaps do something else here

Answer 4

看起来问题在于您正在尝试将\x01\x00 写入特征本身。您需要将其写入执行它的客户端特征配置描述符 (0x2902)。句柄可能比特征大 1（但您可能需要通过阅读描述符来确认）。

ch=chs[1]
cccd = ch.valHandle + 1
cccd.write("\x01\x00")