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diff --git a/examples/bluetooth/heartrate-server/doc/src/heartrate-server.qdoc b/examples/bluetooth/heartrate-server/doc/src/heartrate-server.qdoc new file mode 100644 index 00000000..22c6fcd1 --- /dev/null +++ b/examples/bluetooth/heartrate-server/doc/src/heartrate-server.qdoc @@ -0,0 +1,115 @@ +/**************************************************************************** +** +** Copyright (C) 2016 The Qt Company Ltd. +** Contact: http://www.qt.io/licensing/ +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:FDL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see http://www.qt.io/terms-conditions. For further +** information use the contact form at http://www.qt.io/contact-us. +** +** GNU Free Documentation License Usage +** Alternatively, this file may be used under the terms of the GNU Free +** Documentation License version 1.3 as published by the Free Software +** Foundation and appearing in the file included in the packaging of +** this file. Please review the following information to ensure +** the GNU Free Documentation License version 1.3 requirements +** will be met: http://www.gnu.org/copyleft/fdl.html. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \example heartrate-server + \title Bluetooth Low Energy Heart Rate Server Example + \brief An example demonstrating how to set up and advertise a GATT service. The example + demonstrates the use of the Qt Bluetooth Low Energy classes related to peripheral (slave) + functionality. + + The Bluetooth Low Energy Heart Rate Server is a command-line application that shows how to + develop a Bluetooth GATT server using the Qt Bluetooth API. + The application covers setting up a service, advertising it and notifying clients about changes + to characteristic values. + + The example makes use of the following Qt classes: + + \list + \li \l QLowEnergyAdvertisingData + \li \l QLowEnergyAdvertisingParameters + \li \l QLowEnergyServiceData + \li \l QLowEnergyCharacteristicData + \li \l QLowEnergyDescriptorData + \li \l QLowEnergyController + \li \l QLowEnergyService + + \endlist + + The example implements a server application, which means it has no graphical user interface. + To visualize what it is doing, you can use the \l {heartlistener}{Heart Listener} + example, which is basically the client-side counterpart to this application. + + \note On Linux, advertising requires privileged access, so you need to run + the example as root, for instance via \c sudo. + + \section1 Setting up Advertising Data and Parameters + Two classes are used to configure the advertising process: \l QLowEnergyAdvertisingData to + specify which information is to be broadcast, and \l QLowEnergyAdvertisingParameters for + specific aspects such as setting the advertising interval or controlling which devices are + allowed to connect. In our example, we simply use the default parameters. + + The information contained in the \l QLowEnergyAdvertisingData will be visible to other devices + that are currently scanning. They can use it to decide whether they want to establish a connection + or not. In our example, we include the type of service we offer, a name that adequately + describes our device to humans, and the transmit power level of the device. The latter is + often useful to potential clients, because they can tell how far away our device is by + comparing the received signal strength to the advertised one. + \note Space for the advertising data is very limited (only 31 bytes in total), so + variable-length data such as the device name should be kept as short as possible. + \snippet heartrate-server/main.cpp Advertising Data + + \section1 Setting up Service Data + Next we configure the kind of service we want to offer. We use the \c {Heart Rate} service as + defined in the Bluetooth specification in its minimal form, that is, consisting only of the + \c {Heart Rate Measurement} characteristic. This characteristic must support the \c Notify + property (and no others), and it needs to have a \c {Client Characteristic Configuration} + descriptor, which enables clients to register to get notified about changes to characteristic + values. We set the initial heart rate value to zero, as it cannot be read anyway (the only + way the client can get at the value is via notifications). + \snippet heartrate-server/main.cpp Service Data + + \section1 Advertising and Listening for Incoming Connections + Now that all the data has been set up, we can start advertising. First we create a + \l QLowEnergyController object in the + \l {QLowEnergyController::PeripheralRole} {peripheral role} and use it to create a (dynamic) + \l QLowEnergyService object from our (static) \l QLowEnergyServiceData. + Then we call \l QLowEnergyController::startAdvertising(). + Note that we hand in our \l QLowEnergyAdvertisingData twice: The first argument + acts as the actual advertising data, the second one as the scan response data. They could + transport different information, but here we don't have a need for that. We also pass + a default-constructed instance of \l QLowEnergyAdvertisingParameters, because the default + advertising parameters are fine for us. If a client is interested in the advertised service, + it can now establish a connection to our device. When that happens, the device stops advertising + and the \l QLowEnergyController::connected() signal is emitted. + \note When a client disconnects, advertising does not resume automatically. If you want that + to happen, you need to connect to the \l QLowEnergyController::disconnected() signal + and call \l QLowEnergyController::startAdvertising() in the respective slot. + \snippet heartrate-server/main.cpp Start Advertising + + \section1 Providing the Heartrate + So far, so good. But how does a client actually get at the heart rate? This happens by + regularly updating the value of the respective characteristic in the \l QLowEnergyService + object that we received from the \l QLowEnergyController in the code snippet above. + The source of the heart rate would normally be some kind of sensor, but in our example, + we just make up values that we let oscillate between 60 and 100. The most important part in the + following code snippet is the call to \l QLowEnergyService::writeCharacteristic. If + a client is currently connected and has enabled notifications by writing to the aforementioned + \c {Client Characteristic Configuration}, it will get notified about the new value. + \snippet heartrate-server/main.cpp Provide Heartbeat +*/ + |