Hi Florian,
we are looking into limiting transmit power for our bluetooth file
server project. The idea is to limit sending radius so that people
don't feel harassed if they do not want to receive files.
First we tried to read the RSSI during device discovery and base our
decision on that. But the readings varied too much because of power
saving methods like power tables.
Since we cannot update the firmware of the mobile phones, we decided
to try to limit the transmit power for our device discovery HCI
device. After reading about things a bit and browsing through the
docs that CSR provides, we tried to cap the maximum power or to
change the power tables with the bccmd. Unfortunately, the dongle
doesn't seem to accept the change. After setting the value and re-
reading it, the change is gone:
[root@horst Desktop]# bccmd psget 0x0017
Maximum transmit power: 0x0004 (4)
[root@horst Desktop]# bccmd psset 0x0017 0
[root@horst Desktop]# bccmd psget 0x0017
Maximum transmit power: 0x0004 (4)
I also tried dump all PS keys and restoring the modified dump - same
issue.
Does anybody have experience with this? Do we need special BT
dongles? We are also inquiring with CSR at the moment, but using a
windows software is not an option, as our project is using embedded
Linux (of course :).
this is a hardware detail that you better discuss with CSR people
since while I know a lot about their hardware, I am not that deep into
all the details. And messing with PS keys can result in unexpected
things.
Regards
Marcel
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