Qt and Android characteristicChanged is not emitted

问题

I have a problem with testing my application on Android platform. I have functional application on x86 architecture. This application can connect to Bluetooth LowEnergy device and communicate with it. BT device is HM-10 module - serial line.

But when I try the same application, but just compiled for Android, I'm not able to receive any data back. On the other hand I can see on remote device that all data from mobile terminal are sent.

What I suspect as a possible problem is that signal QLowEnergyService::characteristicChanged is not emitted. In the documentation http://doc.qt.io/qt-5/qlowenergyservice.html is written that you should register for changes, but at least on PC it is done automatically somehow.

Would anyone please help me ?

回答1:

You have to do some magic

QLowEnergyDescriptor notification = _characteristic.descriptor(
    QBluetoothUuid::ClientCharacteristicConfiguration);

if (!notification.isValid()) {
  qDebug() >> "QLowEnergyDescriptor not valid";
}

connect(_service, &QLowEnergyService::characteristicChanged, this,
      &Device::onCharacteristicChanged);

_service->writeDescriptor(notification, QByteArray::fromHex("0100"));

来源：https://stackoverflow.com/questions/37377777/qt-and-android-characteristicchanged-is-not-emitted