Number of Bluetooth Connections

by vishy » Wed, 01 Apr 2009 14:57:49 GMT


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 Hi ,

During our initial testing with Android Phones(Using Cupcake build) we
noticed that the phone connects to more than one BT HF device.Can
anyone share some information on the number of devices Android phones
can connect to via Bluetooth!

Like ,can we connect Phone A to HFP only Headset and PhoneA to A2DP
only Headset,simultaneously!

If multiple connections are supported,what would be the criteria on
which it
is done!

Thanks&Regards,
Vishy
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Number of Bluetooth Connections

by Nick Pelly » Fri, 03 Apr 2009 04:47:36 GMT


 


Have you tried reading the javadoc in BluetoothHeadset.java or
BluetoothA2dp.java ?

Nick

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Number of Bluetooth Connections

by Jackson Fan » Fri, 03 Apr 2009 06:12:07 GMT


 Hi Nick,
         Supporting connection to a single device can be understood. I
want to expand the topic a bit, related to multiple connections to a
same device. For example, cupcake already supports A2DP and HFP
connection to a same headset in concurrent way, although audio data
(A2DP/SCO) need be switched depending on call state. However,
framework code to control such concurrency is weak and cupcake depends
on applications to handle them properly, like in mediaplaybackservice
and BluetoothHandsfree. Are there any plan to support audio switch
from framework level?
         The reason is because cupcake does not implement the
recommendation as from the "Bluetooth White Paper Simultaneous use of
HFP, A2DP, and AVRCP profiles" (url:
https://www.bluetooth.org/docman/handlers/DownloadDoc.ashx?doc_id=49216).
Current A2DP->SCO switch has a limitation depending on other side
interoperating capability - for incoming call case suppose headset
could not echo "A2DP data to close" signal back to phone, I guess A2DP
data channel becomes a unknown state along with SCO being setup. So
during a call in case user still tries to launch music player, effect
depends on hardware implementation of two sides.
         Also suppose later people want to add more profiles,
concurrency need be controlled otherwise data flow competing will
threaten overall quality. I do not know whether you plan to add Qos
mechanism when multiple data related profiles being active, like DUN,
OPP, PBAP, A2DP, PAN, etc? Although conflicting cases may be rare, I
know some carkits can make calls or listening to music while
transferring phonebook entries (via OBEX) via Bluetooth.

Jackson






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Number of Bluetooth Connections

by Nick Pelly » Mon, 06 Apr 2009 23:17:18 GMT


 i 'Jackson Fan',

I agree with your analysis. The framework code to handle A2DP / SCO
transitions could be improved. In the current design A2DP and HFP are
loosely coupled independent services. In retrospect you actually need
a fair degree of coupling between them in order to make the SCO/A2DP
transitions in a way that inter-operates with a greater number of
bluetooth headsets.

We have been planning to add a 'Profile Manager' layer to handle
connection sequence serialization between various profiles.

Nick



On 4/2/09, Jackson Fan <xy...@motorola.com> wrote:

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Number of Bluetooth Connections

by vishy » Thu, 09 Apr 2009 23:20:15 GMT


 Hi Nick,

Guess you are trying to point me to the below statement in
BluetoothHeadset.java!

* Android only supports one connected Bluetooth Headset at a time."

Although we do not observe it every time,we have noticed that it is
possible to connect to a HF Stereo Device and to a HF Mono Device ,
simultaneously!

The Process would be:

1) Pair and connect ,only Media(Under the 'Options' Menu) ,with a
Stereo HF Device
2) Initiate a Connection from a Headset which was previously Paired
with the phone!

Vishy





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Number of Bluetooth Connections

by Nick Pelly » Fri, 10 Apr 2009 03:31:34 GMT


 




Stereo Bluetooth uses a different profile - A2DP.






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Number of Bluetooth Connections

by vishy » Sat, 11 Apr 2009 00:30:24 GMT


 Hi Nick,


the main concern is two ACL connections with two different devices,at
the same time.

Basically it would be helpfull,if we get to know from you guys ,if the
behaviour we notice is a bug(connecting to two different devices at
the same time) or works as designed.

Thanks &Regards,
Vishy








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Number of Bluetooth Connections

by Nick Pelly » Sat, 11 Apr 2009 00:46:54 GMT


 




That is working as designed. The user can have a HFP connection to one
device, and an A2DP connection to another.









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Number of Bluetooth Connections

by vishy » Mon, 13 Apr 2009 23:21:08 GMT


 Hi Nick,

Thanks for the Help.

Regards,
Vishy











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