- Qt 5.15
- Qt Bluetooth
- Qt 5.15.19 Reference Documentation

# Qt Bluetooth

The Bluetooth API provides connectivity between Bluetooth enabled devices.

Currently, the API is supported on the following platforms:

API Feature | Android | iOS | Linux (BlueZ 4.x/5.x) | macOS | UWP (Universal Windows Platform) | Win32
--- | --- | --- | --- | --- | --- | ---
Classic Bluetooth | x |  | x | x | x | x
Bluetooth LE Central | x | x | x | x | x | x
Bluetooth LE Peripheral | x | x | x | x |  |
Bluetooth LE Advertisement & Scanning |  |  |  |  |  |

Qt 5.14 adds a native Win32 port supporting Classic Bluetooth on Windows 7 or newer, and Bluetooth LE on Windows 8 or newer. It must be enabled at build time by configuration option -native-win32-bluetooth. The UWP backend is used by default if this option is not set and the Win32 target platform supports the required UWP APIs (minimal requirement is Windows 10 version 1507, with slightly improved service discovery since Windows 10 version 1607).

## Overview

Bluetooth is a short-range (less than 100 meters) wireless technology. It has a reasonably high data transfer rate of 2.1 Mbit/s, which makes it ideal for transferring data between devices. Bluetooth connectivity is based on basic device management, such as scanning for devices, gathering information about them, and exchanging data between them.

Qt Bluetooth supports Bluetooth Low Energy development for client/central role use cases. Further details can be found in the Bluetooth Low Energy Overview section.

A new addition since the Qt Bluetooth 5.7 release covers support for Bluetooth Low Energy applications performing the peripheral/server role. This new API remains in Technology Preview.

## Getting Started

To use the C++ library in your application, add the following configuration option to your `.pro` file:

     QT += bluetooth

To use the classes of the module in your application you need the following import statement in your `.qml` file:

     import QtBluetooth 5.12

## Related Information

### Building Qt Bluetooth

Despite the fact that the module can be built for all Qt platforms, the module is not ported to all of them. Not supported platforms employ a fake or dummy backend which is automatically selected when the platform is not supported. The dummy backend reports appropriate error messages and values which allow the Qt Bluetooth developer to detect at runtime that the current platform is not supported. The dummy backend is also selected on Linux if BlueZ development headers are not found during build time or Qt was built without Qt D-Bus support.

The usage of the dummy backend is highlighted via an appropriate warning while building and running.

### Guides

- Classic Bluetooth Overview
- Bluetooth Low Energy Overview

### Reference

- QML Types
- C++ Classes

### Logging Categories

The QtBluetooth module exports the following logging categories:

Logging Category | Description
--- | ---
qt.bluetooth | Enables logging of cross platform code path in QtBluetooth
qt.bluetooth.android | Enables logging of the Android implementation
qt.bluetooth.bluez | Enables logging of the BLuez/Linux implementation
qt.bluetooth.ios | Enables logging of the iOS implementation
qt.bluetooth.osx | Enables logging of the macOS implementation
qt.bluetooth.qml | Enables logging of the QtBluetooth QML implementation
qt.bluetooth.winrt | Enables logging of the UWP (Universal Windows Platform) implementation
qt.bluetooth.windows | Enables logging of the Win32 implementation

Logging categories can be used to enable additional warning and debug output for QtBluetooth. More detailed information about logging can be found in QLoggingCategory. A quick way to enable all QtBluetooth logging is to add the following line to the `main()` function:

     QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));

### Examples

- QML
  - QML Bluetooth Scanner
  - QML Bluetooth Picture Push
  - QML Bluetooth PingPong
  - QML Bluetooth Chat
  - Bluetooth Low Energy Heart Rate Game
  - Bluetooth Low Energy Heart Rate Server
  - Bluetooth Low Energy Scanner
- C++
  - Bluetooth Chat
  - Bluetooth Scanner
  - Bluetooth File Transfer

## Licenses and Attributions

Qt Bluetooth is available under commercial licenses from The Qt Company. In addition, it is available under the GNU Lesser General Public License, version 3, or the GNU General Public License, version 2. See Qt Licensing for further details.

On Linux, Qt Bluetooth uses a separate executable, `sdpscanner`, to integrate with the official Linux bluetooth protocol stack BlueZ. BlueZ is available under the GNU General Public License, version 2.

BlueZ | GNU General Public License v2.0 only (This does not force user code to be GPL'ed. For more info see details.)