Re: Losing SCO connection

Michael Oh <[email protected]>
Newsgroups gmane.linux.bluez.user
Message-ID <[email protected]>
It seems like some phones just don't like having a SCO connection up when voice call is not in progress.  So instead of actively trying to connect to the phone, I just let the phone connect to my SCO listener socket as needed and I don't have the disconnect problem anymore.  i.e. I just had to reverse the server/client direction in my app.
There's one remaining problem though.  Occasionally, I hear garbage voice on the receive side of SCO.  hcidump shows maybe the 16-bit samples are in wrong endianness.  This stays like that until the SCO is closed and reestablished.  Anyone seen this problem?   I will try out a CSR dongle also.
Thanks,
Michael

----- Original Message ----
From: Marcel Holtmann <[email protected]>
To: BlueZ users <[email protected]>
Sent: Thursday, May 15, 2008 2:50:32 AM
Subject: Re: [Bluez-users] Losing SCO connection

Hi Michael,

> I wrote a little app that tries to support the hands-free (HF) profile but I am having trouble keeping the SCO connection alive.  Using an RFCOMM connection, I am able to establish the HF Service Level Connection per HF Profile specification and then create an SCO connection to a mobile phone.  But SCO seems to get disconnected by the phone after about 40-50msec of bidirectional voice data.  I can reconnect SCO but the phone disconnects it again.  Once in a while, this problem doesn't occur and SCO stays alive.  When this happens, I can tear down and bring up the HF setup repeatedly without any problem unless I power cycle the phone or the linux machine.  I would like to make it work on consistent basis.
> Please note that I am using the bluez lib only. I am not relying on the "services" utilities in the bluez-util package (I turned them all off).  Also, my SDP setup code seems to operate okay (i.e. output of "sdptool browse local" looks fine)
> Setup:
>    - Fedora 8 with
>        kernel 2.6.24.4
>        bluez-lib 3.20
>        L2CAP v2.9
>        RFCOMM v1.8
>        SCO v0.5
>    - Bluetooth dongle: Targus with Broadcom 2045    - phone: Nokia 6085
> I have tried another phone and another BT dongle and the problem is still there so I am leaning it's either my code or bluez...

did you try a CSR based dongle? It looks like the remote side is
disconnecting. Maybe it has something to do with your HFP control
channel handling. Can't really tell.

Regards

Marcel



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