Is it possible to access iOS GATT Services, e.g. the Battery Service, via GATT over an existing BR/EDR Connection? If yes, what are the pre-conditions?
As current iOS and macOS announces GATT over BR/EDR via an SDP record, I've tried to connect to it via the announced PSM 0x1f, but I get an L2CAP Connection refused – no resources available' (0x04)'. I've tried both as Central without other profiles being connected, as well as Peripheral, after iOS connected to our HFP HF profile?
Why? A customer of our Bluetooth stack wants to build some kind of HFP HF device and has asked us if they can get a better battery status than the 5 levels from HFP. As iOS provides its battery level, it's possible to create an additional LE connection to read the battery status, but it's would be way more elegant and robust, plus require less logic, to access the battery service via the existing BR/EDR connection.
Thanks, Matthias / BlueKitchen GmbH