Qt Bluetooth Low Energy - Problems using non standard GATT

Question

I have a device without knowing the used gatt profile, I only know that is something "homemade" and not anything known on the bluetooth-database.

In Linux the command

gatttool -i hci0  -b xx:xx:xx:xx:xx:xx  --char-read --handle=42

returns the value as expected (with the target device mac at xx:xx:xx:xx:xx:xx).

In Qt I am using the Heartbeat-Example from http://doc-snapshot.qt-project.org/qt5-5.4/qtbluetooth-heartlistener-example.html there they connect using a gattprofile, QBluetoothUuid::HeartRate and QBluetoothUuid::HeartRateMeasurement

I wasn't able to modify the example code in a way to read handle 42. Can you explain where I have to put which values, that it connects to the "standard profile" as the gattool command does? If I use gatttool in interactive mode and ask primary it returns two uuids, but using them instead of the QBluetoothUuid::HeartRate did not work.

Answer 1

It doesn't appear that the Qt Bluetooth Low Energy API provides means for obtaining access to characteristics based on their handle value. (Neither does the Windows 8 BLE API.) You should use the UUID. Even if it's a homemade device, all services and characteristics are required by the GATT protocol to have UUIDs. The lowenergyscanner demo app can discover and display both the UUIDs and handles of all of the device's services and characteristics. I've used lowenergyscanner to deal with BLE devices I'm developing.