[Bluez-devel] full duplex SCO communication for head set profile

[Bluez-devel] full duplex SCO communication for head set profile

[Adam Ritter]

Hi!

I try to use my computer as a headset for a mobile phone. The computer makes an
rfcomm connection and when the mobile makes an SCO connection to the computer,
it accepts it. The computer can read data from the SCO socket, but when it
writes to that socket, the write fails with error ,,Invalid argument''.  Do you
have any ideas what I should do to transfer sound from the computer to the
mobile with that profile?

Adam


# hciconfig -a
hci0:   Type: USB
        BD Address: 00:02:72:B2:F6:72 ACL MTU: 192:8 SCO MTU: 64:8
        UP RUNNING PSCAN ISCAN 
        RX bytes:1362628 acl:313 sco:26537 events:543 errors:0
        TX bytes:5706 acl:238 sco:0 commands:203 errors:0
        Features: 0xff 0xff 0x0f 0x00 0x00 0x00 0x00 0x00
        Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
        Link policy: RSWITCH HOLD SNIFF PARK 
        Link mode: SLAVE ACCEPT 
        Name: 'BlueZ (0)'
        Class: 0x3e0100
        Service Classes: Networking, Rendering, Capturing
        Device Class: Computer, Uncategorized
        HCI Ver: 1.1 (0x1) HCI Rev: 0x20d LMP Ver: 1.1 (0x1) LMP Subver: 0x20d
        Manufacturer: Cambridge Silicon Radio (10)

bash-2.05b# hciconfig hci0 voice
hci0:   Type: USB
        BD Address: 00:02:72:B2:F6:72 ACL MTU: 192:8 SCO MTU: 64:8
        Voice setting: 0x0060 (Default Condition)
        Input Coding: Linear
        Input Data Format: 2's complement
        Input Sample Size: 16 bit
        # of bits padding at MSB: 0
        Air Coding Format: CVSD



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Re: [Bluez-devel] full duplex SCO communication for head set profile

[Luca Pizzamiglio]

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Hash: SHA1

Hi Adam. I suppose that problem is size field of write syscall.
count field of write() or len field of send() must be less or equal of
sco MTU.
if MTU is 64, you can't send a 1024 byte buffer, but you must write 64
byte buffer for 16 times.

Cheers,
Pizza

Adam Ritter wrote:
> Hi!
> 
> I try to use my computer as a headset for a mobile phone. The computer makes an
> rfcomm connection and when the mobile makes an SCO connection to the computer,
> it accepts it. The computer can read data from the SCO socket, but when it
> writes to that socket, the write fails with error ,,Invalid argument''.  Do you
> have any ideas what I should do to transfer sound from the computer to the
> mobile with that profile?
> 
> Adam
> 
> 
> # hciconfig -a
> hci0:   Type: USB
>         BD Address: 00:02:72:B2:F6:72 ACL MTU: 192:8 SCO MTU: 64:8
>         UP RUNNING PSCAN ISCAN 
>         RX bytes:1362628 acl:313 sco:26537 events:543 errors:0
>         TX bytes:5706 acl:238 sco:0 commands:203 errors:0
>         Features: 0xff 0xff 0x0f 0x00 0x00 0x00 0x00 0x00
>         Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3 
>         Link policy: RSWITCH HOLD SNIFF PARK 
>         Link mode: SLAVE ACCEPT 
>         Name: 'BlueZ (0)'
>         Class: 0x3e0100
>         Service Classes: Networking, Rendering, Capturing
>         Device Class: Computer, Uncategorized
>         HCI Ver: 1.1 (0x1) HCI Rev: 0x20d LMP Ver: 1.1 (0x1) LMP Subver: 0x20d
>         Manufacturer: Cambridge Silicon Radio (10)
> 
> bash-2.05b# hciconfig hci0 voice
> hci0:   Type: USB
>         BD Address: 00:02:72:B2:F6:72 ACL MTU: 192:8 SCO MTU: 64:8
>         Voice setting: 0x0060 (Default Condition)
>         Input Coding: Linear
>         Input Data Format: 2's complement
>         Input Sample Size: 16 bit
>         # of bits padding at MSB: 0
>         Air Coding Format: CVSD
> 


- --
- -------------------------------------------
Luca Pizzamiglio
CEFRIEL - Embedded Systems Design Unit
Via Fucini, 2 - 20133 MILANO (ITALY)
Phone:		+39 02 23954 343
e-mail:		pizzamiglio@cefriel.it
ICQ:		5046978
- -------------------------------------------
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