Problem with connecting to a few devices

[Szymon-Gesicki]

• bleak version: 0.5.0
• Python version: 3.7.3
• Operating System: Mac os/Windows

Description

I would like to connect with bleak to a few devices at the same moment and in one terminal. I use loop.create_task() and on windows everything works fine, my two devices notifing perfectly. On Mac os one device also works great but if I try to connect two devices, my devices show that they are connected but they are not notifing. I debug my program and devices get in connect _to_device but print() in 'async with BleakClient() don't show.

from bleak import BleakClient, discover, BleakError
import asyncio

temperatureUUID = "45366e80-cf3a-11e1-9ab4-0002a5d5c51b"
ecgUUID = "46366e80-cf3a-11e1-9ab4-0002a5d5c51b"

def callback(sender, data):
    print(sender, data)

def run(addresses):
    loop = asyncio.get_event_loop()

    for address in addresses:
        loop.create_task(connect_to_device(address, loop))

    loop.run_forever()

async def connect_to_device(address, loop):

    async with BleakClient(address, loop=loop) as client:

        print("connect to ", address)

        await client.start_notify(ecgUUID, callback)

        while True:
            await asyncio.sleep(1, loop=loop)

if __name__ == "__main__":
    run(["9923F33A-0648-4FC4-A062-47C872A4C27D","4CFEB2B0-02E7-46E4-B80D-0B1F5D4AD7CC"])

[hbldh]

Can you try to connect to two devices in macOS using two different terminals and see if that works. If so, then there is a limitation in the bleak macOS backend that needs to be documented.

See this for similar problem: https://stackoverflow.com/questions/34787976/how-can-i-implement-core-bluetooth-functionality-for-multiple-devices

[Szymon-Gesicki]

It took me a while 😀 I did what you said. Bleak connects correctly to two devices at two different terminals. Unfortunately with one terminal, just like in my example, it stops before
async with BleakClient(address, loop=loop) as client:.
On Windows everything works perfect.

[hbldh]

Ok. I will add a note about this in the documentation for the time being. This issue is beyond the scope of my available time to address.

[hbldh]

This is solved in the last develop branch commit and will be available on PyPI in version 0.7.0.

The following code should now work:

from bleak import BleakClient
import asyncio

notify_uuid = "0000{0:x}-0000-1000-8000-00805f9b34fb".format(0xffe1)


def callback(sender, data):
    print(sender, data)


def run(addresses):
    loop = asyncio.get_event_loop()

    tasks = asyncio.gather(
        *(connect_to_device(address, loop) for address in addresses)
    )

    loop.run_until_complete(tasks)


async def connect_to_device(address, loop):
    print("starting", address, "loop")
    async with BleakClient(address, loop=loop, timeout=10.0) as client:

        print("connect to", address)
        try:
            await client.start_notify(notify_uuid, callback)
            await asyncio.sleep(10.0, loop=loop)
            await client.stop_notify(notify_uuid)
        except Exception as e:
            print(e)

    print("disconnect from", address)

if __name__ == "__main__":
    run(["B9EA5233-37EF-4DD6-87A8-2A875E821C46", "F0CBEBD3-299B-4139-A9FC-44618C720157" ])