Re: [Bluez-devel] Question about hci_create_connection and clock offset

Marcel Holtmann
2008-04-24T13:18:17Z

Hi Florian,

> > > However, what I'm trying to do - repeating inquiries in one thread,
> > > checking RSSI in another one (even for devices that haven't been
> > > seen by
> > > the last inquiries) - doesn't seem possible in the D-Bus API, as there
> > > is no function to create a low-level ACL connection to a device
> > > address..?
> > what do you expect from the RSSI value that you get from an active ACL
> > link. It is different from the RSSI value you get via inquiry anyway.
> Well, that wouldn't matter, as I'm going to put all that into a wrapper
> class anyway.
>
> Maybe a word about what I'm trying to do - as you may have guessed
> already, it's about proximity sensing. I've put a minimal Dbus interface
> into my wrapper class and it's actually working quite nicely. However,
> some of the devices which I'm working with - e.g., Motorola mobile
> phones - have a hardcoded discoverable timeout of 3 minutes.
>
> This makes things a bit more difficult for me, as these phones suddenly
> vanish from the list which the Dbus interface is providing, even if they
> are still in range. With the hci_* interface, I can simply try to open
> an ACL connection and get the RSSI value to see if they are just
> invisible. How do I do this with Dbus?

and that RSSI value is totally different from the one you get via an
inquiry and thus you can't put them together. If you could, I would have
done this inside the kernel.

And no matter what you try, creating an ACL baseband connection is most
expensive operation in Bluetooth. So it takes time and that it takes
even more time if you have to wait for the page timeout if the device is
not in range.

Regards

Marcel