>> We have several devices (robots) that we want to
access at the same
>> time from several processes via bluetooth (rfcomm
virtual serial
>> port). Each process first opens a connection to one
robot (/dev/
>> rfcommNN), then communicates with the robot for a
while and finally
>> disconnects.
>>
>> When I launch several processes (about 3-5) at the
same time, usually
>> only one of them succeeds to connect. If I
constantly try to open the
>> devices (in a loop, wait a second and call
"open" again), a couple of
>> them are connected after a while, but not all. Is
there a way to make
>> that work? Does anyone else have experience with
concurrent access to
>> the bluetooth libs?
>
> the baseband of a Bluetooth chip is only capable of
paging one
> device at
> a time. We already had this discussion. You should
better look at the
> mailing list archive.
I found a thread regarding concurrent access where the
solution was
to switch to kernel 2.6. However, I am already working on
kernel 2.6
(RH).
I don't think it is a chip limitation issue. In between, I
modified
my program to maintain several connections in the same
process/thread
and that works perfectly. To be more specific, the following
works
Process 1:
open /dev/rfcomm23
open /dev/rfcomm45
send something to rfcomm23
read from rfcomm23
send something to rfcomm45
read from rfcomm45
close rfcomm23
close rfcomm45
In the multiprocess version, the following two processes run
at the
same time:
Process 1:
open /dev/rfcomm23 until success
send something to rfcomm23
read from rfcomm23
close rfcomm23
Process 2:
open /dev/rfcomm45 until success
send something to rfcomm45
read from rfcomm45
close rfcomm45
While process 1 is trying to open a connection to rfcomm23,
the other
process obviously has to wait until the connection is
established
(that might be a chip limitation). However, as soon as the
connection
is established, the other process should be able to open
rfcomm45
before process 1 closes rfcomm23 ...? Because with all being
done in
the same process, it works as well ...
Thanks in advance for your help. If you already discussed
this, I'm
happy to get a pointer to the corresponding thread.
Thomas
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