Bluetooth v1.2 device sees no SPP capabilities from AC 8265

[BeRoBbg]

Although Bluetooth is considered to be mostly backward compatible, it seems impossible to create a Bluetooth connection via Serial Port Profile from a GNSS device supporting only Bluetooth v1.2 class 2 (Topcon GRS-1) to a Win10 TabletPC (Dell Latitude 5285) with an AC 8265, which (according to the specs) is a Bluetooth 4.2 device. ActiveSync Bluetooth connections between both devices work fine. As do SPP connections from the GRS-1 to TabletPC's with older Bluetooth chipsets. (Especially, when the old Toshiba Bluetooth stack is running on these devices. - Which, sadly, is discontinued and doesn't support the AC 8265.)

The Latitude has PROSet/Wireless v20.120.1.0 installed. Bluetooth stack is standard (current) Microsoft Win10x64Pro. Incoming Serial Port is created and the Latitude is visible to other Bluetooth devices. The Latitude just doesn't propagate SPP server capabilities and therefore the GRS-1 will not create an outgoing serial port for this connection...

Is there a non-circumventable technical reason for this failure? Or is just a setting missing, could another Bluetooth stack (which?) enable the connection, ...?

[Wanner_G_Intel]

Hello BeRoBbg, 

Thank you for providing us with these details.

Wanner G.

Intel Customer Support Technician

Under Contract to Intel Corporation

[BeRoBbg]

Hello Wanner G.,

I had an idea, which got me a huge step forward:

After comparing the registry files of the Topcon GRS-1 Windows Mobile 6.1 device between

(1) A successful paring (including working SPP connection) with an older TabletPC running Win10Pro with Toshiba Bluetooth Stack on an internal BT-183 chip

(2) An incomplete pairing (without option to open an SPP connection) with the Dell Latitude 5285 running Win10Pro with Microsoft Bluetooth Stack on the internal Intel AC 8265

quite a few differences showed up. I concentrated on the subkey listing the properties of the external paired device (xxxxxxxxxxxx being the unambiguous device ID):

[HKEY_LOCAL_MACHINE\Software\Microsoft\Bluetooth\Device\xxxxxxxxxxxx]

While the entries of case (1) showed Service properties for serial port connection, case (2) did not. As a mere tryout I copied the following entries from case (1) to (2):

[HKLM\Software\Microsoft\Bluetooth\Device\xxxxxxxxxxxx\Services]

[HKLM\Software\Microsoft\Bluetooth\Device\xxxxxxxxxxxx\Services\00001101-0000-1000-8000-00805f9b34fb]

"enabled"=dword:00000001

"name"="Serial Port"

"channel"=dword:00650001

Afterwards, I was permitted to create an outgoing port on the GRS-1 which successfully connected to the pre-created outgoing port on the Dell Tablet. A final test showed, that the GNSS data now was flawlessly transmitted from GRS-1 to the TabletPC. I logged this successful connection with the ibttracetool scripts. (You find those files attached to this message as BTTest3.zip.)

Conclusion:

The Intel AC 8265 does permit the SPP connection of older v1.2 Bluetooth devices. And the Bluetooth driver of the AC 8265 as well as the Microsoft Bluetooth stack do handle SPP connections on Win10Pro. The handshake process on pairing, OTOH, seems to be unable to transmit the SPP capabilities between both devices. (Maybe, each device waits for the other to "step forward" and confide in being able to support serial port connections??) Therefore, a registry change is necessary each time the GRS-1 is paired to another device. This is not easy to script, because the device ID of the remote device will always be different...

It would be nice, if you or your colleagues could suggest a way to circumvent the necessity of registry changes on the Windows Mobile device each time a new TabletPC has to be connected. (Maybe a setting for the AC 8265 driver or the Bluetooth stack, that permits a more open announcement of the supported Bluetooth profiles/capabilities?)

[Wanner_G_Intel]

Hello BeRoBbg,

Thank you for your feedback.

We will review it and get back to you soon.

Wanner G.

Intel Customer Support Technician

Under Contract to Intel Corporation

[Wanner_G_Intel]

Hello BeRoBbg,

Thank you for the information you have posted on this thread. It is highly appreciated.

We passed on the details and steps you have performed to the engineering team as a request to take them into account for future driver releases.

We will close this inquiry now. If you need further assistance, we will be glad to assist you.

Wanner G.

Intel Customer Support Technician

Under Contract to Intel Corporation