signature "" on interface ... doesnt exist

[Jeins98]

• bleak version: 0.3
• Python version: 3.6
• Operating System: Ubuntu

Description

I want to connect to an BLE device.

What I Did

Traceback (most recent call last):
  File "/home/jonas/Schreibtisch/TMRTFlib.py", line 572, in <module>
    loop.run_until_complete(connect_device_bleak(address, loop))
  File "/usr/lib/python3.6/asyncio/base_events.py", line 473, in run_until_complete
    return future.result()
  File "/home/jonas/Schreibtisch/TMRTFlib.py", line 552, in connect_device_bleak
    async with BleakClient(address, loop=loop) as client:
  File "/home/jonas/.local/lib/python3.6/site-packages/bleak/backends/client.py", line 35, in __aenter__
    await self.connect()
  File "/home/jonas/.local/lib/python3.6/site-packages/bleak/backends/bluezdbus/client.py", line 76, in connect
    raise BleakError(str(e))
bleak.exc.BleakError: org.freedesktop.DBus.Error.UnknownObject: Method "Connect" with signature "" on interface "org.bluez.Device1" doesn't exist

[hbldh]

I also got this error when I tried at first. Then I performed a discovery operation first (see discover example), and after that it works. It's like the DBus interface must be "started" and have stored a entry about the peripheral you want to connect to.

Try this and it it works I will add a discover action when connect is called.

[Jeins98]

Thanks for awnser. I will try it these days and will give you a statemant

[Jeins98]

40:B8:9A:CE:6A:52: dev_40_B8_9A_CE_6A_52
A4:C1:38:14:43:32: dev_A4_C1_38_14_43_32
40:16:3B:DB:96:E3: dev_40_16_3B_DB_96_E3
6F:63:0A:C8:7C:14: dev_6F_63_0A_C8_7C_14
00:1A:22:0B:43:E9: dev_00_1A_22_0B_43_E9
4B:63:5E:85:8B:D2: dev_4B_63_5E_85_8B_D2
51:B9:7C:1C:84:90: dev_51_B9_7C_1C_84_90

Traceback (most recent call last):
  File "/home/jonas/.local/lib/python3.6/site-packages/bleak/backends/bluezdbus/client.py", line 74, in connect
    ).asFuture(self.loop)
txdbus.error.RemoteError: org.freedesktop.DBus.Error.UnknownObject: Method "Connect" with signature "" on interface "org.bluez.Device1" doesn't exist

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jonas/Schreibtisch/TMRTFlib.py", line 575, in <module>
    loop.run_until_complete(connect_device_bleak(address, loop))
  File "/usr/lib/python3.6/asyncio/base_events.py", line 473, in run_until_complete
    return future.result()
  File "/home/jonas/Schreibtisch/TMRTFlib.py", line 552, in connect_device_bleak
    async with BleakClient(address, loop=loop) as client:
  File "/home/jonas/.local/lib/python3.6/site-packages/bleak/backends/client.py", line 35, in __aenter__
    await self.connect()
  File "/home/jonas/.local/lib/python3.6/site-packages/bleak/backends/bluezdbus/client.py", line 76, in connect
    raise BleakError(str(e))
bleak.exc.BleakError: org.freedesktop.DBus.Error.UnknownObject: Method "Connect" with signature "" on interface "org.bluez.Device1" doesn't exist

I also get this error

[hbldh]

Could you provide a code snippet showing how you create the client and call connect? Try to extract a minimal example that reproduces the error, Also, what version of Ubuntu do you use and what version of BlueZ?

[Jeins98]

Sorry for late awnser. Here is my Code Snippet:

async def measure_battery(self, loop):
     async with BleakClient(self.__address, loop=loop) as client:
          await client.start_notify(self.__BtriggerCharacteristicUUID, self.callback_battery)
          await asyncio.sleep(2.0, loop=loop)
          await client.stop_notify(self.__BtriggerCharacteristicUUID)

async def scan_bleak():
    devices = await discover()
    for d in devices:
        print(d)


if __name__ == "__main__":
    loop = asyncio.get_event_loop()
    loop.run_until_complete(scan_bleak())
    s = Sensor("EC:67:FD:C2:79:1B", 5)
    loop.run_until_complete(s.measure_battery(loop))

And i have bluez in version 5.48 and Ubuntu in 18.04.2

[hbldh]

Ah, this is a bit of a problematic case...

In BlueZ 5.48 they removed the Battery Service (0000180f-0000-1000-8000-00805f9b34fb) from the has been moved to interface org.bluez.Battery1 instead of as a regular service. This has been remedied in Bleak 0.4.0 (which isn't released yet, still in develop branch), at least for the read case; however I have not fixed notifications from the battery service... I will look into this and get back to you.

[hbldh]

After I release version 0.4.0 and you have installed that, try this instead:

async def measure_battery(self, loop):
     async with BleakClient(self.__address, loop=loop) as client:
         battery_level = await client.read_gatt_char(self.__BtriggerCharacteristicUUID)
         print("Battery Level: {0}%".format(int(battery_level[0])))

Notifications on battery level will not work in BlueZ right now; I do not know how to fix that right now. You will have to settle for a regular read.

[Jeins98]

Hi sorry, but I don't use the Battery UUID. It's a Custom Service and it don't work.

[karlp]

I'm getting this still with bluez 5.64 on openwrt (dbus, but not systemd) using the script: https://github.com/etactica/host_utilities/blob/feature/bluetooth_ota_python_bleak/bluetooth_ota_apploader_python_bleak/sl-ota-apploader.py

It happily scans and finds the device, then .... fails to connect. This works fine on fedora desktop with bluez5.65, and it worked "back then" before I updated fedora as well.

Using bluetoothctl, I can see that I must leave scan on to get a connection to succeed? if I do "scan le" my device appears, but if I do "scan off" (to stop the console spam) and then "connect blah" it will fail. if I leave scan on, I can connect just fine