\inmodule QtBluetooth More...

#include <qlowenergycontroller.h>

Inheritance diagram for QLowEnergyController:

Collaboration diagram for QLowEnergyController:

Public Types
enum	Error { NoError , UnknownError , UnknownRemoteDeviceError , NetworkError , InvalidBluetoothAdapterError , ConnectionError , AdvertisingError , RemoteHostClosedError , AuthorizationError , MissingPermissionsError , RssiReadError }
	Indicates all possible error conditions found during the controller's existence. More...

enum	ControllerState { UnconnectedState = 0 , ConnectingState , ConnectedState , DiscoveringState , DiscoveredState , ClosingState , AdvertisingState }
	Indicates the state of the controller object. More...

enum	RemoteAddressType { PublicAddress = 0 , RandomAddress }
	Indicates what type of Bluetooth address the remote device uses. More...

enum	Role { CentralRole , PeripheralRole }
	Indicates the role of the controller object. More...

Signals
void	connected ()
	This signal is emitted when the controller successfully connects to the remote Low Energy device (if the controller is in the \l CentralRole) or if a remote Low Energy device connected to the controller (if the controller is in the \l PeripheralRole).

void	disconnected ()
	This signal is emitted when the controller disconnects from the remote Low Energy device or vice versa.

void	stateChanged (QLowEnergyController::ControllerState state)
	This signal is emitted when the controller's state changes.

void	errorOccurred (QLowEnergyController::Error newError)
	This signal is emitted when an error occurs.

void	mtuChanged (int mtu)
	This signal is emitted as a result of a successful MTU change.

void	rssiRead (qint16 rssi)
	This signal is emitted after successful read of RSSI (received signal strength indicator) for a connected remote device.

void	serviceDiscovered (const QBluetoothUuid &newService)
	This signal is emitted each time a new service is discovered.

void	discoveryFinished ()
	This signal is emitted when the running service discovery finishes.

void	connectionUpdated (const QLowEnergyConnectionParameters &parameters)
	This signal is emitted when the connection parameters change.

Signals inherited from QObject
void	destroyed (QObject *=nullptr)
	This signal is emitted immediately before the object obj is destroyed, after any instances of QPointer have been notified, and cannot be blocked.

void	objectNameChanged (const QString &objectName, QPrivateSignal)
	This signal is emitted after the object's name has been changed.

Public Member Functions
	~QLowEnergyController ()
	Destroys the QLowEnergyController instance.

QBluetoothAddress	localAddress () const
	Returns the address of the local Bluetooth adapter being used for the communication.

QBluetoothAddress	remoteAddress () const
	Returns the address of the remote Bluetooth Low Energy device.

QBluetoothUuid	remoteDeviceUuid () const
	Returns the unique identifier of the remote Bluetooth Low Energy device.

QString	remoteName () const
	Returns the name of the remote Bluetooth Low Energy device, if the controller is in the \l CentralRole.

ControllerState	state () const
	Returns the current state of the controller.

RemoteAddressType	remoteAddressType () const
	Returns the type of \l remoteAddress().

void	setRemoteAddressType (RemoteAddressType type)
	Sets the remote address type.

void	connectToDevice ()
	Connects to the remote Bluetooth Low Energy device.

void	disconnectFromDevice ()
	Disconnects from the remote device.

void	discoverServices ()
	Initiates the service discovery process.

QList< QBluetoothUuid >	services () const
	Returns the list of services offered by the remote device, if the controller is in the \l CentralRole.

QLowEnergyService *	createServiceObject (const QBluetoothUuid &service, QObject *parent=nullptr)
	Creates an instance of the service represented by serviceUuid.

void	startAdvertising (const QLowEnergyAdvertisingParameters &parameters, const QLowEnergyAdvertisingData &advertisingData, const QLowEnergyAdvertisingData &scanResponseData=QLowEnergyAdvertisingData())
	Starts advertising the data given in advertisingData and scanResponseData, using the parameters set in parameters.

void	stopAdvertising ()
	Stops advertising, if this object is currently in the advertising state.

QLowEnergyService *	addService (const QLowEnergyServiceData &service, QObject *parent=nullptr)
	Constructs and returns a \l QLowEnergyService object with parent from service.

void	requestConnectionUpdate (const QLowEnergyConnectionParameters &parameters)
	Requests the controller to update the connection according to parameters.

Error	error () const
	Returns the last occurred error or \l NoError.

QString	errorString () const
	Returns a textual representation of the last occurred error.

Role	role () const
	Returns the role that this controller object is in.

int	mtu () const
	Returns the MTU size.

void	readRssi ()
	readRssi() reads RSSI (received signal strength indicator) for a connected remote device.

Public Member Functions inherited from QObject
Q_INVOKABLE	QObject (QObject *parent=nullptr)
	Constructs an object with parent object parent.

virtual	~QObject ()
	Destroys the object, deleting all its child objects.

virtual bool	event (QEvent *event)
	This virtual function receives events to an object and should return true if the event e was recognized and processed.

virtual bool	eventFilter (QObject watched, QEvent event)
	Filters events if this object has been installed as an event filter for the watched object.

QString	objectName () const

Q_WEAK_OVERLOAD void	setObjectName (const QString &name)
	Sets the object's name to name.

void	setObjectName (QAnyStringView name)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

QBindable< QString >	bindableObjectName ()

bool	isWidgetType () const
	Returns `true` if the object is a widget; otherwise returns `false`.

bool	isWindowType () const
	Returns `true` if the object is a window; otherwise returns `false`.

bool	isQuickItemType () const
	Returns `true` if the object is a QQuickItem; otherwise returns `false`.

bool	signalsBlocked () const noexcept
	Returns `true` if signals are blocked; otherwise returns `false`.

bool	blockSignals (bool b) noexcept
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it).

QThread *	thread () const
	Returns the thread in which the object lives.

void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children.

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)
	This is an overloaded function that will start a timer of type timerType and a timeout of interval milliseconds.

int	startTimer (std::chrono::milliseconds time, Qt::TimerType timerType=Qt::CoarseTimer)

void	killTimer (int id)
	Kills the timer with timer identifier, id.

template<typename T >
T	findChild (const QString &aName=QString(), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns the child of this object that can be cast into type T and that is called name, or \nullptr if there is no such object.

template<typename T >
QList< T >	findChildren (const QString &aName, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects.

template<typename T >
QList< T >	findChildren (Qt::FindChildOptions options=Qt::FindChildrenRecursively) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

const QObjectList &	children () const
	Returns a list of child objects.

void	setParent (QObject *parent)
	Makes the object a child of parent.

void	installEventFilter (QObject *filterObj)
	Installs an event filter filterObj on this object.

void	removeEventFilter (QObject *obj)
	Removes an event filter object obj from this object.

QMetaObject::Connection	connect (const QObject sender, const char signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const

bool	disconnect (const char signal=nullptr, const QObject receiver=nullptr, const char *member=nullptr) const

bool	disconnect (const QObject receiver, const char member=nullptr) const

void	dumpObjectTree () const
	Dumps a tree of children to the debug output.

void	dumpObjectInfo () const
	Dumps information about signal connections, etc.

bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value.

bool	setProperty (const char *name, QVariant &&value)

QVariant	property (const char *name) const
	Returns the value of the object's name property.

QList< QByteArray >	dynamicPropertyNames () const

QBindingStorage *	bindingStorage ()

const QBindingStorage *	bindingStorage () const

QObject *	parent () const
	Returns a pointer to the parent object.

bool	inherits (const char *classname) const
	Returns `true` if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns `false`.

Static Public Member Functions
static QLowEnergyController *	createCentral (const QBluetoothDeviceInfo &remoteDevice, QObject *parent=nullptr)
	Returns a new object of this class that is in the \l CentralRole and has the parent object parent.

static QLowEnergyController *	createCentral (const QBluetoothDeviceInfo &remoteDevice, const QBluetoothAddress &localDevice, QObject *parent=nullptr)
	Returns a new instance of this class with parent.

static QLowEnergyController *	createPeripheral (const QBluetoothAddress &localDevice, QObject *parent=nullptr)
	Returns a new object of this class that is in the \l PeripheralRole and has the parent object parent and is using localDevice.

static QLowEnergyController *	createPeripheral (QObject *parent=nullptr)
	Returns a new object of this class that is in the \l PeripheralRole and has the parent object parent.

Static Public Member Functions inherited from QObject
static QMetaObject::Connection	connect (const QObject sender, const char signal, const QObject receiver, const char member, Qt::ConnectionType=Qt::AutoConnection)
	\threadsafe

static QMetaObject::Connection	connect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::ContextTypeForFunctor< Func2 >::ContextType context, Func2 &&slot, Qt::ConnectionType type=Qt::AutoConnection)

template<typename Func1 , typename Func2 >
static QMetaObject::Connection	connect (const typename QtPrivate::FunctionPointer< Func1 >::Object *sender, Func1 signal, Func2 &&slot)

static bool	disconnect (const QObject sender, const char signal, const QObject receiver, const char member)
	\threadsafe

static bool	disconnect (const QObject sender, const QMetaMethod &signal, const QObject receiver, const QMetaMethod &member)

static bool	disconnect (const QMetaObject::Connection &)
	Disconnect a connection.

template<typename Func1 , typename Func2 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const typename QtPrivate::FunctionPointer< Func2 >::Object receiver, Func2 slot)

template<typename Func1 >
static bool	disconnect (const typename QtPrivate::FunctionPointer< Func1 >::Object sender, Func1 signal, const QObject receiver, void **zero)

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	\threadsafe

Protected Member Functions inherited from QObject
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns \nullptr.

int	senderSignalIndex () const

int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal.

bool	isSignalConnected (const QMetaMethod &signal) const

virtual void	timerEvent (QTimerEvent *event)
	This event handler can be reimplemented in a subclass to receive timer events for the object.

virtual void	childEvent (QChildEvent *event)
	This event handler can be reimplemented in a subclass to receive child events.

virtual void	customEvent (QEvent *event)
	This event handler can be reimplemented in a subclass to receive custom events.

virtual void	connectNotify (const QMetaMethod &signal)

virtual void	disconnectNotify (const QMetaMethod &signal)

	QObject (QObjectPrivate &dd, QObject *parent=nullptr)

Protected Attributes inherited from QObject
QScopedPointer< QObjectData >	d_ptr

Properties inherited from QObject
QString	objectName
	the name of this object

Related Symbols inherited from QObject
template< class T > T	qobject_cast (const QObject *object)
	Returns the given object cast to type T if the object is of type T (or of a subclass); otherwise returns \nullptr.

template< typename T > T	qFindChildqFindChildren (const QObject *obj, const QString &name)()

template< typename T > QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()

	QObjectList
	\macro Q_CLASSINFO(Name, Value)

Detailed Description

\inmodule QtBluetooth

The QLowEnergyController class provides access to Bluetooth Low Energy Devices.

Since: 5.4

QLowEnergyController acts as the entry point for Bluetooth Low Energy development.

Bluetooth Low Energy defines two types of devices; the peripheral and the central. Each role performs a different task. The peripheral device provides data which is utilized by central devices. An example might be a humidity sensor which measures the moisture in a winter garden. A device such as a mobile phone might read the sensor's value and display it to the user in the greater context of all sensors in the same environment. In this case the sensor is the peripheral device and the mobile phone acts as the central device.

A controller in the central role is created via the \l createCentral() factory method. Such an object essentially acts as a placeholder towards a remote Low Energy peripheral device, enabling features such as service discovery and state tracking.

After having created a controller object in the central role, the first step is to establish a connection via \l connectToDevice(). Once the connection has been established, the controller's \l state() changes to \l QLowEnergyController::ConnectedState and the \l connected() signal is emitted. It is important to mention that some platforms such as a BlueZ based Linux cannot maintain two connected instances of \l QLowEnergyController to the same remote device. In such cases the second call to \l connectToDevice() may fail. This limitation may disappear at some stage in the future. The \l disconnectFromDevice() function is used to break the existing connection.

The second step after establishing the connection is to discover the services offered by the remote peripheral device. This process is started via \l discoverServices() and has finished once the \l discoveryFinished() signal has been emitted. The discovered services can be enumerated via \l services().

The last step is to create service objects. The \l createServiceObject() function acts as factory for each service object and expects the service UUID as parameter. The calling context should take ownership of the returned \l QLowEnergyService instance.

Any \l QLowEnergyService, \l QLowEnergyCharacteristic or \l QLowEnergyDescriptor instance which is later created from this controller's connection becomes invalid as soon as the controller disconnects from the remote Bluetooth Low Energy device.

A controller in the peripheral role is created via the \l createPeripheral() factory method. Such an object acts as a peripheral device itself, enabling features such as advertising services and allowing clients to get notified about changes to characteristic values.

After having created a controller object in the peripheral role, the first step is to populate the set of GATT services offered to client devices via calls to \l addService(). Afterwards, one would call \l startAdvertising() to let the device broadcast some data and, depending on the type of advertising being done, also listen for incoming connections from GATT clients.

See also: QLowEnergyService, QLowEnergyCharacteristic, QLowEnergyDescriptor; QLowEnergyAdvertisingParameters, QLowEnergyAdvertisingData

Definition at line 21 of file qlowenergycontroller.h.

Member Enumeration Documentation

◆ ControllerState

enum QLowEnergyController::ControllerState

Indicates the state of the controller object.

\value UnconnectedState The controller is not connected to a remote device. \value ConnectingState The controller is attempting to connect to a remote device. \value ConnectedState The controller is connected to a remote device. \value DiscoveringState The controller is retrieving the list of services offered by the remote device. \value DiscoveredState The controller has discovered all services offered by the remote device. \value ClosingState The controller is about to be disconnected from the remote device. \value [since 5.7] AdvertisingState The controller is currently advertising data.

Enumerator
UnconnectedState
ConnectingState
ConnectedState
DiscoveringState
DiscoveredState
ClosingState
AdvertisingState

Definition at line 40 of file qlowenergycontroller.h.

◆ Error

enum QLowEnergyController::Error

Indicates all possible error conditions found during the controller's existence.

\value NoError No error has occurred. \value UnknownError An unknown error has occurred. \value UnknownRemoteDeviceError The remote Bluetooth Low Energy device with the address passed to the constructor of this class cannot be found. \value NetworkError The attempt to read from or write to the remote device failed. \value InvalidBluetoothAdapterError The local Bluetooth device with the address passed to the constructor of this class cannot be found or there is no local Bluetooth device. \value [since 5.5] ConnectionError The attempt to connect to the remote device failed. \value [since 5.7] AdvertisingError The attempt to start advertising failed. \value [since 5.10] RemoteHostClosedError The remote device closed the connection. \value [since 5.14] AuthorizationError The local Bluetooth device closed the connection due to insufficient authorization. \value [since 6.4] MissingPermissionsError The operating system requests permissions which were not granted by the user. \value [since 6.5] RssiReadError An attempt to read RSSI (received signal strength indicator) of a remote device finished with error.

Enumerator
NoError
UnknownError
UnknownRemoteDeviceError
NetworkError
InvalidBluetoothAdapterError
ConnectionError
AdvertisingError
RemoteHostClosedError
AuthorizationError
MissingPermissionsError
RssiReadError

Definition at line 25 of file qlowenergycontroller.h.

◆ RemoteAddressType

enum QLowEnergyController::RemoteAddressType

Indicates what type of Bluetooth address the remote device uses.

\value PublicAddress The remote device uses a public Bluetooth address. \value RandomAddress A random address is a Bluetooth Low Energy security feature. Peripherals using such addresses may frequently change their Bluetooth address. This information is needed when trying to connect to a peripheral.

Enumerator
PublicAddress
RandomAddress

Definition at line 51 of file qlowenergycontroller.h.

◆ Role

enum QLowEnergyController::Role

Indicates the role of the controller object.

\value CentralRole The controller acts as a client interacting with a remote device which is in the peripheral role. The controller can initiate connections, discover services and read and write characteristics. \value PeripheralRole The controller can be used to advertise services and handle incoming connections and client requests, acting as a GATT server. A remote device connected to the controller is in the central role.

See also: QLowEnergyController::createCentral(); QLowEnergyController::createPeripheral()

Since: 5.7

Note: The peripheral role is not supported on Windows. In addition on Linux, handling the "Signed Write" ATT command on the server side requires BlueZ 5 and kernel version 3.7 or newer.

Enumerator
CentralRole
PeripheralRole

Definition at line 57 of file qlowenergycontroller.h.

Constructor & Destructor Documentation

◆ ~QLowEnergyController()

QLowEnergyController::~QLowEnergyController ( )

Destroys the QLowEnergyController instance.

Definition at line 501 of file qlowenergycontroller.cpp.

References disconnectFromDevice().

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Member Function Documentation

◆ addService()

QLowEnergyService * QLowEnergyController::addService	(	const QLowEnergyServiceData &	service,
		QObject *	parent = `nullptr`
	)

Constructs and returns a \l QLowEnergyService object with parent from service.

The controller must be in the \l PeripheralRole and in the \l UnconnectedState. The service object must be valid.

Note: Once the peripheral instance is disconnected from the remote central device or if \l disconnectFromDevice() is manually called, every service definition that was previously added via this function is removed from the peripheral. Therefore this function must be called again before re-advertising this peripheral controller instance. The described behavior is connection specific and therefore not dependent on whether \l stopAdvertising() was called.

Since: 5.7

See also: stopAdvertising(), disconnectFromDevice(), QLowEnergyServiceData::addIncludedService

Definition at line 826 of file qlowenergycontroller.cpp.

References QBluetoothPermission::Access, d, ensureAndroidPermission(), QObject::parent(), PeripheralRole, qCWarning, role(), QObject::setParent(), state(), and UnconnectedState.

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◆ connected

void QLowEnergyController::connected ( )

signal

This signal is emitted when the controller successfully connects to the remote Low Energy device (if the controller is in the \l CentralRole) or if a remote Low Energy device connected to the controller (if the controller is in the \l PeripheralRole).

On iOS, macOS, and Android this signal is not reliable if the controller is in the \l PeripheralRole. On iOS and macOS the controller only guesses that some central connected to our peripheral as soon as this central tries to write/read a characteristic/descriptor. On Android the controller monitors all connected GATT devices. On Linux BlueZ DBus peripheral backend the remote is considered connected when it first reads/writes a characteristic or a descriptor.

◆ connectionUpdated

void QLowEnergyController::connectionUpdated ( const QLowEnergyConnectionParameters & newParameters )

signal

This signal is emitted when the connection parameters change.

This can happen as a result of calling \l requestConnectionUpdate() or due to other reasons, for instance because the other side of the connection requested new parameters. The new values can be retrieved from newParameters.

Since: 5.7

See also: requestConnectionUpdate()

◆ connectToDevice()

void QLowEnergyController::connectToDevice ( )

Connects to the remote Bluetooth Low Energy device.

This function does nothing if the controller's \l state() is not equal to \l UnconnectedState. The \l connected() signal is emitted once the connection is successfully established.

On Linux/BlueZ systems, it is not possible to connect to the same remote device using two instances of this class. The second call to this function may fail with an error. This limitation may be removed in future releases.

See also: disconnectFromDevice()

Definition at line 621 of file qlowenergycontroller.cpp.

References CentralRole, d, InvalidBluetoothAdapterError, qCWarning, role(), state(), and UnconnectedState.

Referenced by MyClass::btleSharedData(), and MyClass::enableCharNotifications().

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◆ createCentral() [1/2]

QLowEnergyController * QLowEnergyController::createCentral	(	const QBluetoothDeviceInfo &	remoteDevice,
		const QBluetoothAddress &	localDevice,
		QObject *	parent = `nullptr`
	)

static

Returns a new instance of this class with parent.

The remoteDevice must contain the address of the remote Bluetooth Low Energy device to which this object should attempt to connect later on.

The connection is established via localDevice. If localDevice is invalid, the local default device is automatically selected. If localDevice specifies a local device that is not a local Bluetooth adapter, \l error() is set to \l InvalidBluetoothAdapterError once \l connectToDevice() is called.

Note that specifying the local device to be used for the connection is only possible when using BlueZ. All other platforms do not support this feature.

Since: 5.14

Definition at line 434 of file qlowenergycontroller.cpp.

References QObject::parent().

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◆ createCentral() [2/2]

QLowEnergyController * QLowEnergyController::createCentral	(	const QBluetoothDeviceInfo &	remoteDevice,
		QObject *	parent = `nullptr`
	)

static

Returns a new object of this class that is in the \l CentralRole and has the parent object parent.

The remoteDevice refers to the device that a connection will be established to later.

The controller uses the local default Bluetooth adapter for the connection management.

See also: QLowEnergyController::CentralRole

Since: 5.7

Definition at line 412 of file qlowenergycontroller.cpp.

References QObject::parent().

Referenced by MyClass::enableCharNotifications().

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◆ createPeripheral() [1/2]

QLowEnergyController * QLowEnergyController::createPeripheral	(	const QBluetoothAddress &	localDevice,
		QObject *	parent = `nullptr`
	)

static

Returns a new object of this class that is in the \l PeripheralRole and has the parent object parent and is using localDevice.

Typically, the next steps are to add some services and finally call \l startAdvertising() on the returned object.

The peripheral is created on localDevice. If localDevice is invalid, the local default device is automatically selected. If localDevice specifies a local device that is not a local Bluetooth adapter, \l error() is set to \l InvalidBluetoothAdapterError.

Selecting localDevice is only supported on Linux. On other platform, the parameter is ignored.

See also: QLowEnergyController::PeripheralRole

Since: 6.2

Definition at line 475 of file qlowenergycontroller.cpp.

References QObject::parent().

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◆ createPeripheral() [2/2]

QLowEnergyController * QLowEnergyController::createPeripheral ( QObject * parent = nullptr )

static

Returns a new object of this class that is in the \l PeripheralRole and has the parent object parent.

Typically, the next steps are to add some services and finally call \l startAdvertising() on the returned object.

The controller uses the local default Bluetooth adapter for the connection management.

See also: QLowEnergyController::PeripheralRole

Since: 5.7

Definition at line 453 of file qlowenergycontroller.cpp.

References QObject::parent().

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◆ createServiceObject()

QLowEnergyService * QLowEnergyController::createServiceObject	(	const QBluetoothUuid &	serviceUuid,
		QObject *	parent = `nullptr`
	)

Creates an instance of the service represented by serviceUuid.

The serviceUuid parameter must have been obtained via \l services().

The caller takes ownership of the returned pointer and may pass a parent parameter as default owner.

This function returns a null pointer if no service with serviceUuid can be found on the remote device or the controller is disconnected.

This function can return instances for secondary services too. The include relationships between services can be expressed via \l QLowEnergyService::includedServices().

If this function is called multiple times using the same service UUID, the returned \l QLowEnergyService instances share their internal data. Therefore if one of the instances initiates the discovery of the service details, the other instances automatically transition into the discovery state too.

See also: services()

Definition at line 738 of file qlowenergycontroller.cpp.

References d, it, and QObject::parent().

Referenced by MyClass::btleSharedData(), and MyClass::enableCharNotifications().

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◆ disconnected

void QLowEnergyController::disconnected ( )

signal

This signal is emitted when the controller disconnects from the remote Low Energy device or vice versa.

On iOS and macOS this signal is unreliable if the controller is in the \l PeripheralRole. On Android the signal is emitted when the last connected device is disconnected. On BlueZ DBus backend the controller is considered disconnected when last client which has accessed the attributes has disconnected.

◆ disconnectFromDevice()

void QLowEnergyController::disconnectFromDevice ( )

Disconnects from the remote device.

Any \l QLowEnergyService, \l QLowEnergyCharacteristic or \l QLowEnergyDescriptor instance that resulted from the current connection is automatically invalidated. Once any of those objects become invalid they remain invalid even if this controller object reconnects.

This function does nothing if the controller is in the \l UnconnectedState.

If the controller is in the peripheral role, it stops advertising and removes all services which have previously been added via \l addService(). To reuse the QLowEnergyController instance the application must re-add services and restart the advertising mode by calling \l startAdvertising().

See also: connectToDevice()

Definition at line 659 of file qlowenergycontroller.cpp.

References d, state(), and UnconnectedState.

Referenced by ~QLowEnergyController().

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◆ discoverServices()

void QLowEnergyController::discoverServices ( )

Initiates the service discovery process.

The discovery progress is indicated via the \l serviceDiscovered() signal. The \l discoveryFinished() signal is emitted when the process has finished.

If the controller instance is not connected or the controller has performed the service discovery already this function will do nothing.

Note: Some platforms internally cache the service list of a device which was discovered in the past. This can be problematic if the remote device changed its list of services or their inclusion tree. If this behavior is a problem, the best workaround is to temporarily turn Bluetooth off. This causes a reset of the cache data. Currently Android exhibits such a cache behavior.

Definition at line 686 of file qlowenergycontroller.cpp.

References CentralRole, ConnectedState, d, DiscoveringState, and qCWarning.

◆ discoveryFinished

void QLowEnergyController::discoveryFinished ( )

signal

This signal is emitted when the running service discovery finishes.

The signal is not emitted if the discovery process finishes with an error.

This signal can only be emitted if the controller is in the \l CentralRole.

See also: discoverServices(), error()

◆ error()

QLowEnergyController::Error QLowEnergyController::error ( ) const

Returns the last occurred error or \l NoError.

Definition at line 895 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::error.

◆ errorOccurred

void QLowEnergyController::errorOccurred ( QLowEnergyController::Error newError )

signal

This signal is emitted when an error occurs.

The newError parameter describes the error that occurred.

See also: error(), errorString()

Since: 6.2

◆ errorString()

QString QLowEnergyController::errorString ( ) const

Returns a textual representation of the last occurred error.

The string is translated.

Definition at line 904 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::errorString.

◆ localAddress()

QBluetoothAddress QLowEnergyController::localAddress ( ) const

Returns the address of the local Bluetooth adapter being used for the communication.

If this class instance was requested to use the default adapter but there was no default adapter when creating this class instance, the returned \l QBluetoothAddress will be null.

See also: QBluetoothAddress::isNull()

Definition at line 517 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::localAdapter.

◆ mtu()

int QLowEnergyController::mtu ( ) const

Returns the MTU size.

During connection setup, the ATT MTU size is negotiated. This method provides the result of this negotiation. It can be used to optimize packet sizes in some situations. The maximum amount of data which can be transferred in a single packet is {mtu-3} bytes. 3 bytes are required for the ATT protocol header.

Before the connection setup and MTU negotiation, the default value of 23 will be returned.

Not every platform exposes the MTU value. On those platforms (e.g. Linux) this function always returns -1.

If the controller is in the \l PeripheralRole, there might be several central devices connected to it. In those cases this function returns the MTU of the last connection that was negotiated.

Since: 6.2

Definition at line 944 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::mtu().

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◆ mtuChanged

void QLowEnergyController::mtuChanged ( int mtu )

signal

This signal is emitted as a result of a successful MTU change.

mtu represents the new value.

Note: If the controller is in the \l PeripheralRole, the MTU value is negotiated for each client/central device individually. Therefore this signal can be emitted several times in a row for one or several devices.

See also: mtu()

◆ readRssi()

void QLowEnergyController::readRssi ( )

readRssi() reads RSSI (received signal strength indicator) for a connected remote device.

If the read was successful, the RSSI is then reported by rssiRead() signal.

Note: Prior to calling readRssi(), this controller must be connected to a peripheral. This controller must be created using createCentral().; In case Bluetooth backend you are using does not support reading RSSI, the errorOccurred() signal is emitted with an error code QLowEnergyController::RssiReadError. At the moment platforms supporting reading RSSI include Android, iOS and macOS.

See also: rssiRead(), connectToDevice(), state(), createCentral(), errorOccurred()

Since: 6.5

Definition at line 963 of file qlowenergycontroller.cpp.

References CentralRole, ClosingState, ConnectingState, qCWarning, QLowEnergyControllerPrivate::readRssi(), role(), RssiReadError, QLowEnergyControllerPrivate::setError(), state(), and UnconnectedState.

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◆ remoteAddress()

QBluetoothAddress QLowEnergyController::remoteAddress ( ) const

Returns the address of the remote Bluetooth Low Energy device.

For a controller in the \l CentralRole, this value will always be the one passed in when the controller object was created. For a controller in the \l PeripheralRole, this value is one of the currently connected client device addresses. This address will be invalid if the controller is not currently in the \l ConnectedState.

Definition at line 530 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::remoteDevice.

◆ remoteAddressType()

QLowEnergyController::RemoteAddressType QLowEnergyController::remoteAddressType ( ) const

Returns the type of \l remoteAddress().

By default, this value is initialized to \l PublicAddress.

See also: setRemoteAddressType()

Definition at line 579 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::addressType.

◆ remoteDeviceUuid()

QBluetoothUuid QLowEnergyController::remoteDeviceUuid ( ) const

Returns the unique identifier of the remote Bluetooth Low Energy device.

On macOS/iOS/tvOS CoreBluetooth does not expose/accept hardware addresses for LE devices; instead developers are supposed to use unique 128-bit UUIDs, generated by CoreBluetooth. These UUIDS will stay constant for the same central <-> peripheral pair and we use them when connecting to a remote device. For a controller in the \l CentralRole, this value will always be the one passed in when the controller object was created. For a controller in the \l PeripheralRole, this value is invalid.

Since: 5.8

Definition at line 547 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::deviceUuid.

◆ remoteName()

QString QLowEnergyController::remoteName ( ) const

Returns the name of the remote Bluetooth Low Energy device, if the controller is in the \l CentralRole.

Otherwise the result is unspecified.

Since: 5.5

Definition at line 558 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::remoteName.

◆ requestConnectionUpdate()

void QLowEnergyController::requestConnectionUpdate ( const QLowEnergyConnectionParameters & parameters )

Requests the controller to update the connection according to parameters.

If the request is successful, the \l connectionUpdated() signal will be emitted with the actual new parameters. See the \l QLowEnergyConnectionParameters class for more information on connection parameters.

Android only indirectly permits the adjustment of this parameter set. The connection parameters are separated into three categories (high, low & balanced priority). Each category implies a pre-configured set of values for \l QLowEnergyConnectionParameters::minimumInterval(), \l QLowEnergyConnectionParameters::maximumInterval() and \l QLowEnergyConnectionParameters::latency(). Although the connection request is an asynchronous operation, Android does not provide a callback stating the result of the request. This is an acknowledged Android bug. Due to this bug Android does not emit the \l connectionUpdated() signal.

Note: Currently, this functionality is only implemented on Linux kernel backend and Android.

See also: connectionUpdated()

Since: 5.7

Definition at line 879 of file qlowenergycontroller.cpp.

References ConnectedState, DiscoveredState, DiscoveringState, qCWarning, QLowEnergyControllerPrivate::requestConnectionUpdate(), and state().

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◆ role()

QLowEnergyController::Role QLowEnergyController::role ( ) const

Returns the role that this controller object is in.

The role is determined when constructing a QLowEnergyController instance using \l createCentral() or \l createPeripheral().

Since: 5.7

Definition at line 917 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::role.

Referenced by addService(), connectToDevice(), readRssi(), and startAdvertising().

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◆ rssiRead

void QLowEnergyController::rssiRead ( qint16 rssi )

signal

This signal is emitted after successful read of RSSI (received signal strength indicator) for a connected remote device.

rssi parameter represents the new value.

See also: readRssi()

Since: 6.5

◆ serviceDiscovered

void QLowEnergyController::serviceDiscovered ( const QBluetoothUuid & newService )

signal

This signal is emitted each time a new service is discovered.

The newService parameter contains the UUID of the found service.

This signal can only be emitted if the controller is in the CentralRole.

See also: discoverServices(), discoveryFinished()

◆ services()

QList< QBluetoothUuid > QLowEnergyController::services ( ) const

Returns the list of services offered by the remote device, if the controller is in the \l CentralRole.

Otherwise, the result is unspecified.

The list contains all primary and secondary services.

See also: createServiceObject()

Definition at line 709 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::serviceList.

◆ setRemoteAddressType()

void QLowEnergyController::setRemoteAddressType ( QLowEnergyController::RemoteAddressType type )

Sets the remote address type.

The type is required to connect to the remote Bluetooth Low Energy device.

This attribute is only required to be set on Linux/BlueZ systems with older Linux kernels (v3.3 or lower), or if CAP_NET_ADMIN is not set for the executable. The default value of the attribute is \l RandomAddress.

Note: All other platforms handle this flag transparently and therefore applications can ignore it entirely. On Linux, the address type flag is not directly exposed by BlueZ although some use cases do require this information. The only way to detect the flag is via the Linux kernel's Bluetooth Management API (kernel version 3.4+ required). This API requires CAP_NET_ADMIN capabilities though. If the local QtBluetooth process has this capability set QtBluetooth will use the API. This assumes that \l QBluetoothDeviceDiscoveryAgent was used prior to calling \l QLowEnergyController::connectToDevice().

Definition at line 601 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::addressType.

◆ startAdvertising()

void QLowEnergyController::startAdvertising	(	const QLowEnergyAdvertisingParameters &	parameters,
		const QLowEnergyAdvertisingData &	advertisingData,
		const QLowEnergyAdvertisingData &	scanResponseData = `QLowEnergyAdvertisingData()`
	)

Starts advertising the data given in advertisingData and scanResponseData, using the parameters set in parameters.

The controller has to be in the \l PeripheralRole. If parameters indicates that the advertisement should be connectable, then this function also starts listening for incoming client connections.

Providing scanResponseData is not required, as it is not applicable for certain configurations of parameters. advertisingData and scanResponseData are limited to 31 byte user data. If, for example, several 128bit uuids are added to advertisingData, the advertised packets may not contain all uuids. The existing limit may have caused the truncation of uuids. In such cases scanResponseData may be used for additional information.

On BlueZ DBus backend BlueZ decides if, and which data, to use in a scan response. Therefore all advertisement data is recommended to set in the main advertisingData parameter. If both advertisement and scan response data is set, the scan response data is given precedence.

If this object is currently not in the \l UnconnectedState, nothing happens.

Since: 5.7

See also: stopAdvertising()

Definition at line 776 of file qlowenergycontroller.cpp.

References d, PeripheralRole, qCWarning, role(), state(), and UnconnectedState.

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◆ state()

QLowEnergyController::ControllerState QLowEnergyController::state ( ) const

Returns the current state of the controller.

See also: stateChanged()

Definition at line 568 of file qlowenergycontroller.cpp.

References QLowEnergyControllerPrivate::state.

Referenced by addService(), connectToDevice(), disconnectFromDevice(), readRssi(), requestConnectionUpdate(), startAdvertising(), and stopAdvertising().

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◆ stateChanged

void QLowEnergyController::stateChanged ( QLowEnergyController::ControllerState state )

signal

This signal is emitted when the controller's state changes.

The new state can also be retrieved via \l state().

See also: state()

◆ stopAdvertising()

void QLowEnergyController::stopAdvertising ( )

Stops advertising, if this object is currently in the advertising state.

The controller has to be in the \l PeripheralRole for this function to work. It does not invalidate services which have previously been added via \l addService().

Since: 5.7

See also: startAdvertising()

Definition at line 801 of file qlowenergycontroller.cpp.

References AdvertisingState, d, qCDebug, and state().

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The documentation for this class was generated from the following files:

qtconnectivity/src/bluetooth/qlowenergycontroller.h
qtconnectivity/src/bluetooth/qlowenergycontroller.cpp

Public Types

Signals

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ ControllerState

◆ Error

◆ RemoteAddressType

◆ Role

Constructor & Destructor Documentation

◆ ~QLowEnergyController()

Member Function Documentation

◆ addService()

◆ connected

◆ connectionUpdated

◆ connectToDevice()

◆ createCentral() [1/2]

◆ createCentral() [2/2]

◆ createPeripheral() [1/2]

◆ createPeripheral() [2/2]

◆ createServiceObject()

◆ disconnected

◆ disconnectFromDevice()

◆ discoverServices()

◆ discoveryFinished

◆ error()

◆ errorOccurred

◆ errorString()

◆ localAddress()

◆ mtu()

◆ mtuChanged

◆ readRssi()

◆ remoteAddress()

◆ remoteAddressType()

◆ remoteDeviceUuid()

◆ remoteName()

◆ requestConnectionUpdate()

◆ role()

◆ rssiRead

◆ serviceDiscovered

◆ services()

◆ setRemoteAddressType()

◆ startAdvertising()

◆ state()

◆ stateChanged

◆ stopAdvertising()