Re: Access iOS GATT Services over BR/EDR
Re: Access iOS GATT Services over BR/EDR
- Subject: Re: Access iOS GATT Services over BR/EDR
- From: Matthias Ringwald via Bluetooth-dev <email@hidden>
- Date: Tue, 9 May 2023 11:08:44 +0200
Hi Duy
Thanks for your reply. This not about accessing remote GATT Services via BR/EDR
via the CoreBluetooth APIs from an iOS device.
It's about reading the iPhone battery level from a device connected via BR/EDR
in a headset/hands-free role to show on a head unit in a car or a dashboard on
a motor bike
As we can successfully query the iOS GATT Battery Service via LE, we've tried
to use GATT over BR/EDR from the hands-free unit as the connection already
exists for HFP HF/A2DP Sink.
After getting the ATT PSM (0x1f) from the GATT SDP Service Record, we get an
L2CAP Connection refused – no resources available' (0x04)' when trying to open
the L2CAP Connection to that PSM.
I'll attach PacketLogger files from our stack as well as from the iPhone.
Please let me know if there's anything obviously wrong or If I should file a
feedback/bug report with that.
Best regards
Matthias
> On 4 May 2023, at 22:48, Duy Phan <email@hidden> wrote:
>
> Hi Matthias,
> It’s our intention for developers to have same access to GATT services over
> BDR/EDR.
>
> Could you help file a feedback report and sysdiagnose (with logging profile)
> so we can understand how you’re using the APIs?
> Thank you!
> Duy
>
>> On Apr 11, 2023, at 7:22 AM, Matthias Ringwald via Bluetooth-dev
>> <email@hidden> wrote:
>>
>> Hi there
>>
>> Is it possible to access iOS GATT Services, e.g. the Battery Service, via
>> GATT over an existing BR/EDR Connection?
>>
>> As current iOS and macOS announce GATT over BR/EDR via an SDP record, I've
>> tried to connect to it via the announced PSM 0x1f, but I get an L2CAP
>> Connection refused – no resources available' (0x04)'.
>> I've tried both as Central without other profiles being connected, as well
>> as Peripheral, after iOS connected to our HFP HF profile?
>>
>> Why? A customer of our stack wants to build some kind of HFP HF device and
>> has asked us if they can get a better battery status than the 5 levels from
>> HFP.
>> As iOS provides it's battery level, it's possible to create an additional LE
>> connection to read the battery status, but it's would be way more elegant,
>> and requires less logic, to access the battery service via
>> the existing BR/EDR connection.
>>
>> Thanks
>> Matthias
>>
>> —
>> Dr. sc. Matthias Ringwald
>> CTO and Co-founder of BlueKitchen GmbH, Zurich
>> https://bluekitchen-gmbh.com <https://bluekitchen-gmbh.com/>
>>
Attachment:
gatt-over-classic-from-accessory-2.zip
Description: Zip archive
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