Hi All,
I'm having some difficulties getting the gatt-example plugin working.
I've checked out the latest tag (5.14) from git and have built it
using the --enable-maintainer-mode configure flag so that
gatt-example.c is compiled into a static plugin that is loaded at
runtime. I've confirmed that the plugin is compiled and is loaded at
runtime when I run bluetoothd.
My problem is with making modifications to the plugin. I've tried
something as simple as changing the UUID for the battery service,
however, every time I scan the services (using an iPhone), the same
list of UUIDs is returned (0xA002 , 0xA004, and 0xFEEE... for the
services, which match up with what's defined in the gatt-example.c
file). Any modifications I make to the file don't seem to have any
effect on the services advertised. I've even rebuilt it without
maintainer mode and have confirmed the plugin isn't loaded, but still,
the same set of services and characteristics are loaded. Is there some
sort of cache where the advertisement is loaded from that can be
cleared? It looks like a bunch of HCI Commands are sent every time I
"hciconfig hci0 up" which didn't happen when I initially ran the
hciconfig tool prior to compiling and running bluetoothd.
Some additional details:
Bluetooth adapter is a Broadcom (in a MacBook Pro) that is running
through a Linux VM (VirtualBox). Additional diagnostics can be
provided on request.
Thanks for any help you guys can provide,
Sandy
--
Hi Anderson,
On Mon, Feb 3, 2014 at 11:51 AM, Anderson Lizardo
<[email protected]> wrote:
> Hi Sandy,
>
> On Mon, Feb 3, 2014 at 10:38 AM, Sandy Chapman <[email protected]> wrote:
>> Hi All,
>>
>> I'm having some difficulties getting the gatt-example plugin working.
>> I've checked out the latest tag (5.14) from git and have built it
>> using the --enable-maintainer-mode configure flag so that
>> gatt-example.c is compiled into a static plugin that is loaded at
>> runtime. I've confirmed that the plugin is compiled and is loaded at
>> runtime when I run bluetoothd.
>>
>> My problem is with making modifications to the plugin. I've tried
>> something as simple as changing the UUID for the battery service,
>> however, every time I scan the services (using an iPhone), the same
>> list of UUIDs is returned (0xA002 , 0xA004, and 0xFEEE... for the
>> services, which match up with what's defined in the gatt-example.c
>> file). Any modifications I make to the file don't seem to have any
>> effect on the services advertised. I've even rebuilt it without
>> maintainer mode and have confirmed the plugin isn't loaded, but still,
>> the same set of services and characteristics are loaded. Is there some
>> sort of cache where the advertisement is loaded from that can be
>> cleared? It looks like a bunch of HCI Commands are sent every time I
>> "hciconfig hci0 up" which didn't happen when I initially ran the
>> hciconfig tool prior to compiling and running bluetoothd.
>
> Most likely iPhone is caching the attribute database and thus not
> redoing any discovery. If this is the case, it is because we don't
> provide a Service Changed characteristic on the GATT service,
> therefore the iPhone thinks the database is static.
>
> BTW this is a bug/limitation on the current BlueZ. While working on
> the new GATT API we are also implementing a Service Changed service
> that notifies changes to the entire database on every connection. This
> is suboptimal (may trigger service discovery on every connection) but
> at least will avoid stale cache on the client side. In future we need
> to implement tracking of added / removed services and notify only
> those that change.
>
> Please use "btmon" while iphone connects to bluez and check if there
> is any ATT traffic for GATT service discovery.
>
> If this is the case, you need to find out how to clear the cache on the iPhone.
>
> Best Regards,
> --
> Anderson Lizardo
> http://www.indt.org/?lang=en
> INdT - Manaus - Brazil
This was exactly the problem. Apple doesn't provide any API to reset
the GATT cache and neglects to mention that fact. Turns out, disabling
and re-enabling Bluetooth on iOS clears the cache. After doing this,
my updated UUIDs are shown on the phone correctly. For reference, this
is the stack overflow link that points this out:
http://stackoverflow.com/q/17090949/1270148
Thanks,
Sandy
--
Hi Sandy,
On Mon, Feb 3, 2014 at 10:38 AM, Sandy Chapman <[email protected]> wrote:
> Hi All,
>
> I'm having some difficulties getting the gatt-example plugin working.
> I've checked out the latest tag (5.14) from git and have built it
> using the --enable-maintainer-mode configure flag so that
> gatt-example.c is compiled into a static plugin that is loaded at
> runtime. I've confirmed that the plugin is compiled and is loaded at
> runtime when I run bluetoothd.
>
> My problem is with making modifications to the plugin. I've tried
> something as simple as changing the UUID for the battery service,
> however, every time I scan the services (using an iPhone), the same
> list of UUIDs is returned (0xA002 , 0xA004, and 0xFEEE... for the
> services, which match up with what's defined in the gatt-example.c
> file). Any modifications I make to the file don't seem to have any
> effect on the services advertised. I've even rebuilt it without
> maintainer mode and have confirmed the plugin isn't loaded, but still,
> the same set of services and characteristics are loaded. Is there some
> sort of cache where the advertisement is loaded from that can be
> cleared? It looks like a bunch of HCI Commands are sent every time I
> "hciconfig hci0 up" which didn't happen when I initially ran the
> hciconfig tool prior to compiling and running bluetoothd.
Most likely iPhone is caching the attribute database and thus not
redoing any discovery. If this is the case, it is because we don't
provide a Service Changed characteristic on the GATT service,
therefore the iPhone thinks the database is static.
BTW this is a bug/limitation on the current BlueZ. While working on
the new GATT API we are also implementing a Service Changed service
that notifies changes to the entire database on every connection. This
is suboptimal (may trigger service discovery on every connection) but
at least will avoid stale cache on the client side. In future we need
to implement tracking of added / removed services and notify only
those that change.
Please use "btmon" while iphone connects to bluez and check if there
is any ATT traffic for GATT service discovery.
If this is the case, you need to find out how to clear the cache on the iPhone.
Best Regards,
--
Anderson Lizardo
http://www.indt.org/?lang=en
INdT - Manaus - Brazil