Re: [Bluez-devel] Reading RSSI of non-connected devices

[Marcel Holtmann <marcel@holtmann.org>]

Hi Andreas,

> >the ioctl() is very old and number updated it to support Inquiry with
> >RSSI or Extended Inquiry. The main reason for this is, because you can't
> >update it without breaking backward-compatibility with older versions of
> >the library and the tools.
> >
> >However you can program the HCI socket interface directly and read the
> >inquiry result directly. Example code for this is already available in
> >the mailing list archives.
> >  
> >
> Some posts say ioctl was bad because it's old, some posts say raw HCI 
> sockets were bad because the messed with BlueZ. Your hcitool apparently 
> is using ioctl for "hcitool scan" in its most recent version 
> downloadable from your site...

you should avoid interfacing with the kernel, but listening for events
on the HCI socket was and will be always safe.

> Our software is a Java framework that shall continuously check the RSSI 
> of devices around in a background thread (test code for this is in C). 
> Another thread might be continuously using GPS data via BT and apart 
> from that we don't want to keep the user from using the BlueZ stack in a 
> "normal" way while our software is running. In this context is it safe 
> to use HCI sockets in the way you have suggested?

In this case you should use periodic inquiry and listen for inquiry
result events on the HCI raw socket. This is a safe way of doing it. You
might wanna check out the D-Bus interface, but this new API might be
still changed at lot.

> I'm having a hard time finding the example you're mentioning over and 
> over... Do you have any search words for me?
> Not having found it I would assume you mean hci_open_dev and 
> hci_send_cmd? Examples for the latter would be in the kernel driver 
> which I already have.

Try to look for EVT_INQUIRY_RESULT_WITH_RSSI.

Regards

Marcel




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