Android BLE Library

An Android library that solves a lot of Android's Bluetooth Low Energy problems. The BleManager class exposes high level API for connecting and communicating with Bluetooth LE peripherals. The API is clean and easy to read.

Features

BleManager class provides the following features:

1. Connection, with automatic retries
2. Service discovery
3. Bonding (optional) and removing bond information (using reflections)
4. Automatic handling of Service Changed indications
5. Device initialization
6. Asynchronous and synchronous BLE operations using queue
7. Splitting and merging long packets when writing and reading characteristics and descriptors
8. Requesting MTU and connection priority (on Android Lollipop or newer)
9. Reading and setting preferred PHY (on Android Oreo or newer)
10. Reading RSSI
11. Refreshing device cache (using reflections)
12. Reliable Write support
13. Operation timeouts (for connect, disconnect and wait for notification requests)
14. Error handling
15. Logging

The library does not provide support for scanning for Bluetooth LE devices. For scanning, we recommend using Android Scanner Compat Library which brings almost all recent features, introduced in Lollipop and later, to the older platforms.

Importing

Maven Central or jcenter

The library may be found on jcenter and Maven Central repository. Add it to your project by adding the following dependency:

implementation 'no.nordicsemi.android:ble:2.1.1'

The last version not migrated to AndroidX is 2.0.5.

As a library module

Clone this project and add ble module as a dependency to your project:

1. In settings.gradle file add the following lines:

include ':ble'
project(':ble').projectDir = file('../Android-BLE-Library/ble')

2. In app/build.gradle file add implementation project(':ble') inside dependencies.
3. Sync project and build it.

Usage

BleManager may be used for a single connection (see nRF Toolbox -> RSC profile) or when multiple connections are required (see nRF Toolbox -> Proximity profile), from a Service (see nRF Toolbox -> RSC profile), ViewModel's repo (see Architecture Components and nRF Blinky), or as a singleton (not recommended, see nRF Toolbox -> HRM).

A single BleManager instance is responsible for connecting and communicating with a single peripheral. Multiple manager instances are allowed. Extend BleManager with you manager where you define the high level device's API.

Changes in version 2.0:

1. BLE operation methods (i.e. writeCharacteristic(...), etc.) return the Request class now, instead of boolean.
2. onLinklossOccur callback has been renamed to onLinkLossOccurred.
3. GATT callbacks (for example: onCharacteristicRead, onCharacteristicNotified, etc.) inside BleManagerGattCallback has been deprecated. Use Request callbacks instead.
4. Build-in Battery Level support has been deprecated. Request Battery Level as any other value.
5. A new callbacks method: onBondingFailed has been added to BleManagerCallbacks.
6. shouldAutoConnect() has ben deprecated, use useAutoConnect(boolean) in ConnectRequest instead.
7. Timeout is supported for connect, disconnect and wait for notification/indication. Most BLE operations do not support setting timeout, as receiving the BluetoothGattCallback is required in order to perform the next operation.
8. Atomic RequestQueue and ReliableWriteRequest are supported.
9. BLE Library 2.0 uses Java 8. There's no good reason for this except to push the ecosystem to having this be a default. As of AGP 3.2 there is no reason not to do this (via butterknife).

Migration guide:

1. Replace initGatt(BluetoothGatt) with initialize():

Old code:

@Override
protected Deque<Request> initGatt(final BluetoothGatt gatt) {
  final LinkedList<Request> requests = new LinkedList<>();
  requests.add(Request.newEnableNotificationsRequest(characteristic));
  return requests;
}

New code:

@Override
protected void initialize() {
  setNotificationCallback(characteristic)
    .with(new DataReceivedCallback() {
      @Override
      public void onDataReceived(@NonNull final BluetoothDevice device, @NonNull final Data data) {
        ...
      }
    });
  enableNotifications(characteristic)
    .enqueue();
}

See changes in Android nRF Toolbox and Android nRF Blinky for more examples.

Remember to call .enqueue() method for initialization requests!

Connect's completion callback is called after the initialization is done (without or with errors).

2. Move your callback implementation from BleManagerGattCallback to request callbacks.
3. To split logic from parsing, we recommend to extend DataReceivedCallback interface in a class where your parse your data, and return higher-level values. For a sample, check out nRF Toolbox and Android BLE Common Library. If you are depending on a SIG adopted profile, like Heart Rate Monitor, Proximity, etc., feel free to include the BLE Common Library in your project. It has all the parsers implemented. If your profile isn't there, we are happy to accept PRs.
4. connect() and disconnect() methods also require calling .enqueue() in asynchronous use.
5. Replace the shouldAutoConnect() method in the manager with connect(device).useAutConnect(true).enqueue()/await().

How to test it:

The new version is compatible with nRF Toolbox and BLE Common Library. The latter one is a set of useful parsers and callbacks for common Bluetooth SIG adopted profiles.

The libraries are available on jcenter, but if you need to make some changes, clone all 3 projects, ensure the path to :ble and :ble-common modules are correct in settings.gradle file, and sync the project.

How to use it

Find the simple example here Android nRF Blinky.

For an example how to use it from an Activity or a Service, check the base Activity and Service classes in nRF Toolbox.

1. Define your device API by extending BleManagerCallbacks: example
2. Extend BleManager class and implement required methods: example

Version 1.x

The BLE library v 1.x is no longer supported. Please migrate to 2.x for bug fixing releases. Find it on version/1x branch.