我尝试使用Python控制某些BLE GATT设备。我发现Bleak（https://bleak.readthedocs.io/en/latest/）这个库可以与GATT设备通信。
当我使用它时，大多数时候它确实运行良好。
但是，一旦我尝试与BLE GATT医疗设备进行通信，我发现我无法始终使用此设备进行通知。
这是我的代码，我对Bleak的github示例进行了一些更改：( https://github.com/hbldh/bleak/blob/develop/examples/enable_notifications.py）
import asyncio
import logging
from bleak import discover
from bleak import BleakClient
devices_dict = {}
devices_list = []
receive_data = []
#To discover BLE devices nearby
async def scan():
dev = await discover()
for i in range(0,len(dev)):
#Print the devices discovered
print("[" + str(i) + "]" + dev[i].address,dev[i].name,dev[i].metadata["uuids"])
#Put devices information into list
devices_dict[dev[i].address] = []
devices_dict[dev[i].address].append(dev[i].name)
devices_dict[dev[i].address].append(dev[i].metadata["uuids"])
devices_list.append(dev[i].address)
#An easy notify function, just print the recieve data
def notification_handler(sender, data):
print(', '.join('{:02x}'.format(x) for x in data))
async def run(address, debug=False):
log = logging.getLogger(__name__)
if debug:
import sys
log.setLevel(logging.DEBUG)
h = logging.StreamHandler(sys.stdout)
h.setLevel(logging.DEBUG)
log.addHandler(h)
async with BleakClient(address) as client:
x = await client.is_connected()
log.info("Connected: {0}".format(x))
for service in client.services:
log.info("[Service] {0}: {1}".format(service.uuid, service.description))
for char in service.characteristics:
if "read" in char.properties:
try:
value = bytes(await client.read_gatt_char(char.uuid))
except Exception as e:
value = str(e).encode()
else:
value = None
log.info(
"\t[Characteristic] {0}: (Handle: {1}) ({2}) | Name: {3}, Value: {4} ".format(
char.uuid,
char.handle,
",".join(char.properties),
char.description,
value,
)
)
for descriptor in char.descriptors:
value = await client.read_gatt_descriptor(descriptor.handle)
log.info(
"\t\t[Descriptor] {0}: (Handle: {1}) | Value: {2} ".format(
descriptor.uuid, descriptor.handle, bytes(value)
)
)
#Characteristic uuid
CHARACTERISTIC_UUID = "put your characteristic uuid"
await client.start_notify(CHARACTERISTIC_UUID, notification_handler)
await asyncio.sleep(5.0)
await client.stop_notify(CHARACTERISTIC_UUID)
if __name__ == "__main__":
print("Scanning for peripherals...")
#Build an event loop
loop = asyncio.get_event_loop()
#Run the discover event
loop.run_until_complete(scan())
#let user chose the device
index = input('please select device from 0 to ' + str(len(devices_list)) + ":")
index = int(index)
address = devices_list[index]
print("Address is " + address)
#Run notify event
loop = asyncio.get_event_loop()
loop.set_debug(True)
loop.run_until_complete(run(address, True))
在大多数情况下，此代码可以很好地用作此图像。
但是有时候（大约25％的比率），这个问题就发生了：
[0]08:6B:D7:12:F1:33 Nonin3150_502892837['uuid']
[1]1D:BD:4A:69:8B:AB Unknown []
[2]73:15:CD:47:AF:08 Unknown []
[3]40:4E:36:5B:8D:1B HTC BS 1BBDB9 ['uuid']
[4]6B:FB:E5:DD:7F:4E Unknown []
[5]69:A7:87:23:5C:7C Unknown []
please select device from 0 to 6:0
Address is 08:6B:D7:12:F1:33
Traceback (most recent call last):
File "D:/Bletest/nonin_test.py", line 91, in <module>
loop.run_until_complete(run(address, True))
File "C:\Users\rizal\AppData\Local\Programs\Python\Python37\lib\asyncio\base_events.py", line 579, in run_until_complete
return future.result()
File "D:/Bletest/nonin_test.py", line 36, in run
async with BleakClient(address) as client:
File "C:\Users\rizal\AppData\Local\Programs\Python\Python37\lib\site-packages\bleak\backends\client.py", line 60, in __aenter__
await self.connect()
File "C:\Users\rizal\AppData\Local\Programs\Python\Python37\lib\site-packages\bleak\backends\dotnet\client.py", line 154, in connect
"Device with address {0} was not found.".format(self.address)
bleak.exc.BleakError: Device with address 08:6B:D7:12:F1:33 was not found.
Process finished with exit code 1
我不知道为什么程序可以发现此设备，但无法通知它。
这是我的代码问题，还是可能是由该设备的程序流程引起的？
我确实有同样的问题。但是，我认为这与Windows中BLE的实现有关。在Windows界面中扫描设备时，有时可以看到设备的外观和消失情况。设备广告间隔可能很长。
但是，可以通过将其包装在try catch部分中来进行修复。
这样的事情可能对您有用。
async def connect_to_device(self):
while True:
if self.connection_enabled:
try:
await self.client.connect()
self.connected = await self.client.is_connected()
if self.connected:
print("Connected to Device")
self.client.set_disconnected_callback(self.on_disconnect)
await self.client.start_notify(
self.notify_characteristic, self.notify_callback,
)
while True:
if not self.connected:
break
await asyncio.sleep(1.0)
else:
print(f"Failed to connect to Device")
except Exception as e:
print(e)
else:
await asyncio.sleep(1.0)
您只需要将此任务添加到循环中
asyncio.ensure_future(self.connect_to_device(), loop)
定义客户
self.client = BleakClient(self.connected_device.address, loop=loop)
并启用连接
self.connection_enabled = true
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我来说两句