Bluetooth LE Library for Android

This library allows for easy access to a Bluetooth LE device's Advertisement Records. It also offers:

• A simple running average RSSI reading keeping.
• For iBeacons: Manufacturer data record parser.
• For iBeacons: Distance indicators (Near, Far, Immediate, Unknown).
• For iBeacons: A decently inaccurate (due to real world issues) distance approximation.
• All the new object types are Parcelable.

This will only work on devices with Android 4.3 (API Level 18) and above.

Including the Library in Your Project

This project is available as an artifact for use with Gradle. To use that, add the following blocks to your build.gradle file:

 repositories {
  maven {
   url "https://dl.bintray.com/alt236/maven"
  }
 }

 dependencies {
  compile 'uk.co.alt236:bluetooth-le-library-android:1.0.0'
 }

If you really need a Jar file, fork the project and execute ./gradlew clean build generateRelease at the root of the project. This will create a zip file under <PROJECT_ROOT>/library/build/ the Jar can be found inside.

Using the Library

In the onLeScan() method of your BluetoothAdapter.LeScanCallback() create a new BluetoothLeDevice with the given information.

For example:

 private BluetoothAdapter.LeScanCallback mLeScanCallback = new BluetoothAdapter.LeScanCallback() {

  @Override
  public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {

   final BluetoothLeDevice deviceLe = new BluetoothLeDevice(device, rssi, scanRecord, System.currentTimeMillis());

   runOnUiThread(new Runnable() {
    @Override
    public void run() {
     mDeviceStore.addDevice(deviceLe);
     mLeDeviceListAdapter.replaceData(mDeviceStore.getDeviceList());
    }

   });
  }
 };

Device Properties

Once you have created a device, you can access the following methods:

• getAddress() : Gets the MAC Address of the device
• getAdRecordStore(): Gives access to a device's Ad Records
• getDevice(): Gives access to the standard BluetoothDevice object
• getFirstRssi(): Retrieves the RSSI value which was used when the object was created
• getFirstTimestamp() Retrieves the timestamp (in millis) which was used when the object was created
• getRssi() Gets the current RSSI measurement (see note below).
• getScanRecord() Retrieves the RAW scan record array
• getTimestamp() Gets the timestamp of the last RSSI measurement
• getRunningAverageRssi() Retrieves the internally calculated running average RSSI value (see note below).

Note: The Running Average RSSI is not updated automatically (i.e. the library does not monitor on its own in the background). To add another measurement, you need to call updateRssiReading(long timestamp, int rssiReading).

Accessing the Advertisement (Ad) Records

Once you've created a BluetoothLe device, you can access the AdRecord store via the leDevice.getAdRecordStore(). Once you have the AdRecordStore you can use the following methods:

• getRecord(int recordNo): Gets the AdRecord object corresponding to the recordNumber.
• getRecordDataAsString(int recordNo) : Gets the AdRecord contents as a String (expect non printable characters in most cases).
• isRecordPresent(int recordNo): Checks to see if a record exists.

Note: Record numbers are declared in the Bluetooth 4 spec which can be found here. They are also declared as constants in AdRecord.java.

Fun with iBeacons

You can check if a device is an iBeacon by using BeaconUtils.getBeaconType(BluetootLeDevice device). Once you have confirmed that it is, you can create a new IBeaconDevice via the IBeaconDevice constructor.

Example Flow:

 final BluetoothLeDevice device = ... // A generic BLE device

 if (BeaconUtils.getBeaconType(device) == BeaconType.IBEACON) {
  final IBeaconDevice iBeacon = new IBeaconDevice(device);
  // DO STUFF
 }

An IBeaconDevice extends BluetoothLeDevice, so you still have access to the same methods as before. In addition you can do the following:

• getAccuracy(): Gets the estimated Accuracy of the reading in meters based on a simple running average calculation
• getCalibratedTxPower(): Gets the calibrated TX power of the iBeacon device as reported
• getCompanyIdentifier(): Gets the iBeacon company identifier (this should always be 0x004C for Apple)
• getDistanceDescriptor(): Gets the estimated Distance descriptor (an enum)
• getIBeaconData(): Gets the raw IBeaconManufacturerData object.
• getUUID(): Gets the device's UUID
• getMajor(): Gets the device's Major value
• getMinor(): Gets the device's Minor value

Lookup Functions

You can also lookup values and convert them to human friendly strings:

• BluetoothClassResolver.resolveDeviceClass(int btClass): Will try to resolve a Blueotooth Device class
• CompanyIdentifierResolver.getCompanyName(int companyId, String fallback): Will try to resolve a Company identifier to the company name
• GattAttributeResolver.getAttributeName(String uuid, String fallback): Will try to convert a UUID to its name.

Note: The data can be found as ODS (Open Office Spreadsheets) in the documents folder.

Library Changelog

• v0.0.1
  • First public release
• v0.0.2:
  • Attempting to create an iBeaconDevice from a device which is not an iBeacon will now throw an IllegalArgumentException exception.
  • Fixed a ConcurrentModificationException on getRunningAverageRssi()
  • Added some Estimote UUIDs
• v1.0.0:
  • Migrated project to Android Studio/ gradle
  • Note that the API has slightly changed in this version.
  • We now use the more generic BeaconUtils.getBeaconType() method instead of IBeaconUtils.isThisAnIBeacon()
  • Fix for issue 5
  • Fix for issue 9

Sample Application Changelog

• v0.0.1
  • First public release
• v0.0.2:
  • Can now export scanned devices as a CSV file.
• v0.0.3:
  • UI Refresh.
• v1.0.0:
  • Migrated project to Android Studio/ gradle
  • Using version v1.0.0 of the library project
• v1.1.0:
  • App refactor and materialisation.
  • Added runtime permissions.
• v1.1.1:
  • Fix for issue 23

Permission Explanation

You will need the following permissions to access the Bluetooth Hardware

• android.permission.BLUETOOTH
• android.permission.BLUETOOTH_ADMIN

In addition one of the following is needed from API 23 and above to scan for BT LE devices:

• android.permission.ACCESS_COARSE_LOCATION
• android.permission.ACCESS_FINE_LOCATION

TODO

• Tidy up Javadoc. There is quite a lot of it that is template
• Add parsers for common Ad Records.

Links

• Github: https://github.com/alt236/Bluetooth-LE-Library---Android

Credits

Author: Alexandros Schillings.

• The Accuracy calculation algorithm was taken from: http://stackoverflow.com/questions/20416218/understanding-ibeacon-distancing
• The AdRecord parser was taken from: https://github.com/devunwired/accessory-samples
• The sample application has been adapted from Android's Bluetooth LE example
• Google Play and the Google Play logo are trademarks of Google Inc.

All logos are the property of their respective owners.

The code in this project is licensed under the Apache Software License 2.0.

Copyright (c) 2014-2017 Alexandros Schillings.