[Interest] Qt5.7 BLE advertising, contents added twice

[Marco Trapanese]

Hello!
With Qt5.7 under Linux Debian (kernel 4.4.11-v7+, bluez 5.40) I set up
my own GATT server.

QLowEnergyAdvertisingData advertisingData;
advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);
advertisingData.setIncludePowerLevel(false);
advertisingData.setLocalName("0123456789");
leController->startAdvertising(QLowEnergyAdvertisingParameters(),
advertisingData, QLowEnergyAdvertisingData());
advertisingData.setServices(QList<QBluetoothUuid>() << [my-128-bit-uuid]);
qt.bluetooth.bluez: services data does not fit into advertising data
packet

inspecting the advertising data with the Android app from Nordic, I see
the LocalName is set 2 times! And I can't see my uuid.
Is this the correct behavior? Am I missing something?

Thanks!
Marco

[Christian Kandeler]

Post by Marco Trapanese
With Qt5.7 under Linux Debian (kernel 4.4.11-v7+, bluez 5.40) I set up
my own GATT server.

QLowEnergyAdvertisingData advertisingData;

As explained in the documentation of this class, advertising data is a
scarce resource: There are only 31 bytes available in such a packet.

Post by Marco Trapanese

advertisingData.setDiscoverability(QLowEnergyAdvertisingData::DiscoverabilityGeneral);

This information takes one byte plus two bytes of meta data. You have 28
bytes left.

Post by Marco Trapanese

advertisingData.setLocalName("0123456789");

This information takes 10 bytes plus two bytes of meta data. You have 16
bytes left.

Post by Marco Trapanese

advertisingData.setServices(QList<QBluetoothUuid>() <<

[my-128-bit-uuid]);

This information takes 16 bytes plus two bytes of meta data. You would

Post by Marco Trapanese

qt.bluetooth.bluez: services data does not fit into advertising data
packet

is correct.

Post by Marco Trapanese
inspecting the advertising data with the Android app from Nordic, I see
the LocalName is set 2 times!

Nah, whatever you see there is just an artifact of whatever the client
app does.

Post by Marco Trapanese
And I can't see my uuid.

Obviously not, as it could not be added on the server side.

Post by Marco Trapanese
Is this the correct behavior? Am I missing something?

Yes, it is. You need to shorten the local name to eight bytes or less.


Christian

[Marco Trapanese]

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