[Bluez-devel] RFCOMM communication gets stalled

[Bluez-devel] RFCOMM communication gets stalled

[Carlos AM]

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Hi

I'm using bluez-libs-2.7 and bluez-utils-2.7 to develop a GPS system that communicates via bluetooth. I use the RFCOMM and the connection and disconnection works fine but the transmission gets stalled in about ten minutes. Both sides indicate that they are still connected, but in the GPS side, the process that writes in the rfcomm device (/dev/bluetooth/rfcomm/0) stops on a blocking write call:

    write(fdbluetooth,s,strlen(s));

I open the rfcomm device this way:

    fdbluetooth= open("/dev/bluetooth/rfcomm/0",O_RDWR | O_NOCTTY);


That write call works fine for a while until the communication gets stalled.

Is a bad implementation of the process that writes in the rfcomm device?
Is that issue solved in the 2.8 version of bluez?



Carlos AM
Naxus Conectividad Móvil

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Re: [Bluez-devel] RFCOMM communication gets stalled

[Marcel Holtmann]

Hi Carlos,

> I'm using bluez-libs-2.7 and bluez-utils-2.7 to develop a GPS system
> that communicates via bluetooth. I use the RFCOMM and the connection
> and disconnection works fine but the transmission gets stalled in
> about ten minutes. Both sides indicate that they are still connected,
> but in the GPS side, the process that writes in the rfcomm device
> (/dev/bluetooth/rfcomm/0) stops on a blocking write call:
>  
>     write(fdbluetooth,s,strlen(s));
>  
> I open the rfcomm device this way:
>  
>     fdbluetooth= open("/dev/bluetooth/rfcomm/0",O_RDWR | O_NOCTTY);
>  
>  
> That write call works fine for a while until the communication gets
> stalled.

don't use the RFCOMM TTY terminal emulation. Go directly throught the
RFCOMM socket interface. If you still got problems check with hcidump
what is going on.

Regards

Marcel




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RE: [Bluez-devel] RFCOMM communication gets stalled

[Williams, Richard]

Marcel,

I use the rfcomm tty interface quite successfully for sending GPS data
strings from a GPS receiver to an Ipaq and then to another small wrist =
display.
Why use the rfcomm socket interface instead of the TTY ?=20

Should I consider changing my code from TTY to socket ? Its not so =
difficult, I just
wonder why you recommend one vs the other.

thanks and Best regards,

Rich

-----Original Message-----
From: Marcel Holtmann [mailto:marcel@holtmann.org]
Sent: Thursday, July 15, 2004 1:49 PM
To: Carlos AM
Cc: lista bluez
Subject: Re: [Bluez-devel] RFCOMM communication gets stalled


Hi Carlos,

> I'm using bluez-libs-2.7 and bluez-utils-2.7 to develop a GPS system
> that communicates via bluetooth. I use the RFCOMM and the connection
> and disconnection works fine but the transmission gets stalled in
> about ten minutes. Both sides indicate that they are still connected,
> but in the GPS side, the process that writes in the rfcomm device
> (/dev/bluetooth/rfcomm/0) stops on a blocking write call:
> =20
>     write(fdbluetooth,s,strlen(s));
> =20
> I open the rfcomm device this way:
> =20
>     fdbluetooth=3D open("/dev/bluetooth/rfcomm/0",O_RDWR | O_NOCTTY);
> =20
> =20
> That write call works fine for a while until the communication gets
> stalled.

don't use the RFCOMM TTY terminal emulation. Go directly throught the
RFCOMM socket interface. If you still got problems check with hcidump
what is going on.

Regards

Marcel




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RE: [Bluez-devel] RFCOMM communication gets stalled

[Marcel Holtmann]

Hi Richard,

> I use the rfcomm tty interface quite successfully for sending GPS data
> strings from a GPS receiver to an Ipaq and then to another small wrist display.
> Why use the rfcomm socket interface instead of the TTY ? 
> 
> Should I consider changing my code from TTY to socket ? Its not so difficult, I just
> wonder why you recommend one vs the other.

the question is what is the advantage of keeping a legacy TTY if you
already have the source code? There is no difference between a socket
descriptor and a file descriptor, so why involve another subsystem?

Regards

Marcel




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