[Interest] QBluetoothServiceDiscoveryAgent cannot retrieve sdp uuids

[Jérôme Godbout]

I also tried to recreate a new service agent for each scan, with the same
result. The BLE stack crash and system notify with popup.

On 16 August 2018 at 15:10, Jérôme Godbout <godboutj at amotus.ca> wrote:

> > Minimal discovery only uses cached SDP values. If the platform does not
> have any values the above message is the result. You have to do an active
> scan/FullDiscovery.
>
> How can we check if the device support the minimal discovery method? I
> just get an empty result and a trace into the console. It's like it failed
> silently to the application code and only leave a trace into the debug
> console.
>
> >  This is a problem. Please report a bug
> As for the full discovery I end up with the following error popup on the
> Android device from the system*:*
> *"Unfortunately, Bluetooth Share has stopped."* with an ok button. After
> that the whole blueooth is shutdown on the device!
> it's the system Bluetooth stack that crash hard! The scan emit error
> signal: PoweredOffError
> Seem like if the device cannot be reach on the second scan it does crash
> the bluetooth stack and bring the Android Bluetooth service along with it!
>
> I have to quit the application and restart the Bluetooth stack and start
> over and always get the same result with the complete scan!?!?
>
> On 16 August 2018 at 01:51, Alex Blasche <alexander.blasche at qt.io> wrote:
>
>>
>>
>> > -----Original Message-----
>> > From: Interest <interest-bounces+alexander.blasche=qt.io at qt-project.org>
>> On
>> > Behalf Of Jérôme Godbout
>> > Sent: Wednesday, 15 August 2018 21:55
>> > To: Qt Interest <interest at qt-project.org>
>> > Subject: [Interest] QBluetoothServiceDiscoveryAgent cannot retrieve
>> sdp uuids
>> >
>> > Hi,
>> > I'm trying to discover some particular Bluetooth device on Android, but
>> I have
>> > some trouble using the QBluetoothServiceDiscoveryAgent. Here's the
>> workflow:
>> >
>> > 1.    Scan using QBluetoothDeviceDiscoveryAgent to discovers all
>> devices.
>> > 2.    Wait for scan to complete, wait for finished() signal.
>> > 3.    Start a scan  QBluetoothServiceDiscoveryAgent for found devices
>> one by
>> > one. Using start(QBluetoothServiceDiscoveryAgent::MinimalDiscovery). I
>> always
>> > end up with the following error: cannot retrieve sdp uuids.
>>
>> Minimal discovery only uses cached SDP values. If the platform does not
>> have any values the above message is the result. You have to do an active
>> scan/FullDiscovery.
>>
>> > If I try the complete
>> > discovery it just crash hard!
>>
>> This is a problem. Please report a bug (https://bugreports.qt.io) that
>> included your Qt version, a stack trace and ideally a small test program
>> that reproduces the problem for you.
>>
>> > I want to discover any device that can offer a particular services and
>> I don't
>> > controls device name nor the advertising of the BLE devices. Anyway to
>> do this?
>> > Or is it a bug with my Android device or am I using it improperly?
>>
>> If you are looking for BLE services they cannot be retrieved using the
>> SDP (QBluetoothServiceDiscoveryAgent) unless the device choose to use a
>> classic advertisement too. That's usually not the case though.
>>
>>
>> > Do I have to use QLowEnergyControl and connect to each device one by
>> one to
>> > fetch the services list on Android to do this?
>>
>> Usually you should be able to identify the device using the device
>> discovery already as the device discovery reveals quite a bit of
>> information already. Otherwise yes, you actually have to connect.
>>
>> --
>> Alex
>> _______________________________________________
>> Interest mailing list
>> Interest at qt-project.org
>> http://lists.qt-project.org/mailman/listinfo/interest
>>
>
>
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