Simple SDP and RFCOMM example

Simple SDP and RFCOMM example

[Kristóf Horváth]

Hello,

I started a project with Bluetooth, but most of the resources on the
internet use older versions of BlueZ (and often mention using
compatibility mode to hack the legacy code). I think the reason for
the hacking is that there is not any tutorial for BlueZ 5 (or it is in
some very hidden place). I browsed the page
https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test for
examples, and I found some interesting codes, but I could not find
what I was searching for.

I would like to see a simple Python code that can register a service
via SDP and receive the incoming RFCOMM connections. Could you provide
an example like that?

Thank you for your help.

Regards,
Kristóf Horváth

Re: Simple SDP and RFCOMM example

[Szymon Janc]

Hi,

On Tuesday, 12 November 2019 10:15:38 CET Kristóf Horváth wrote:
> Hello,
> 
> I started a project with Bluetooth, but most of the resources on the
> internet use older versions of BlueZ (and often mention using
> compatibility mode to hack the legacy code). I think the reason for
> the hacking is that there is not any tutorial for BlueZ 5 (or it is in
> some very hidden place). I browsed the page
> https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/test for
> examples, and I found some interesting codes, but I could not find
> what I was searching for.
> 
> I would like to see a simple Python code that can register a service
> via SDP and receive the incoming RFCOMM connections. Could you provide
> an example like that?
> 
> Thank you for your help.

There is test/test-profile and test/test-hfp in BlueZ source code.

-- 
pozdrawiam
Szymon Janc

Re: Simple SDP and RFCOMM example

[Kristóf Horváth]

Hi,

> There is test/test-profile and test/test-hfp in BlueZ source code.

Thank you very much. Without a table of contents, it's hard to find
the appropriate scripts. (This is also true for the files in folder
doc.)

With the test-profile code, I could register a service, and I could
discover it from another device. However, a connection couldn't build
up. The function NewConnection didn't call at all. (By the way, I
didn't find any line of code to receive the data, how is it possible?)

I monitored the connection-attempt with bluetoothctl (every row starts
with the prefix "[chg] Device {address of the other device}"):

ServiceResolved: yes
Paired: yes
(There was a little pause here.)
ServiceResolved: no
Paired: no
Connected: no

Have you got any idea what the problem is? Thank you for your help.

Regards,
Kristóf Horváth

Re: Simple SDP and RFCOMM example

[Barry Byford]

On Wed, 13 Nov 2019 at 17:29, Kristóf Horváth
<horvath.kristof.attila@gmail.com> wrote:
>
> Hi,
>
> > There is test/test-profile and test/test-hfp in BlueZ source code.
> With the test-profile code, I could register a service, and I could
> discover it from another device. However, a connection couldn't build
> up. The function NewConnection didn't call at all. (By the way, I
> didn't find any line of code to receive the data, how is it possible?)

Here is an example of receiving data with a Serial Port Profile:
https://gist.github.com/ukBaz/217875c83c2535d22a16ba38fc8f2a91

Going back to your original question, you might find it easier to use
a Python library like Blue Dot on your project as it presents a higher
level interface:
https://bluedot.readthedocs.io/en/latest/btcommapi.html

Regards,
Barry