'Android BLE - Connecting to multiple devices seem to fail and GATT Response is the same for both connections?
I am developing an Android Application that connects to a BLE Device and reads the specific GATT Characteristics and Services that I need to check. I used the BluetoothLeGATT example from the Android Dev site as my reference. I can connect to a predefined Address without problems and read the GATT Attribute updates.
What I want to do next is to be able to connect to two BLE Devices simultaneously. However, this seems to be a challenge.
What I did was to essentially duplicate the code needed to connect to a single BLE Device. I had 2 BluetoothLeServices, 2 ArrayLists for the GattCharacteristics and Gatt Service Data, as well as 2 Service Connections, and 2 Broadcast Receivers for GattCallbacks.
However, in my GattCallback functions, I get the same message -- as if they were connected to the same area. Here is my code:
public class MainActivity extends AppCompatActivity {
/*
UUIDs
Dog Block - 20:CD:39:87:DC:AA
Cat Block - 20:CD:39:87:DF:82
*/
private final String TAG = this.getClass().getSimpleName();
private BluetoothAdapter mBluetoothAdapter;
private Handler mHandler;
private static final int REQUEST_ENABLE_BT = 1;
private static final long SCAN_PERIOD = 10000;
private ArrayList<String> addressID = new ArrayList<>();
private ArrayList<BluetoothDevice> deviceList = new ArrayList<>();
private boolean mScanning = false;
private boolean mConnected = false;
private BluetoothLeService mBluetoothLeService;
private BluetoothLeService mBluetoothLeService1;
private ArrayList<ArrayList<BluetoothGattCharacteristic>> mGattCharacteristics =
new ArrayList<ArrayList<BluetoothGattCharacteristic>>();
private ArrayList<ArrayList<BluetoothGattCharacteristic>> mGattCharacteristics1 =
new ArrayList<ArrayList<BluetoothGattCharacteristic>>();
private final String LIST_NAME = "NAME";
private final String LIST_UUID = "UUID";
ArrayList<HashMap<String, String>> gattServiceData = new ArrayList<HashMap<String, String>>();
ArrayList<ArrayList<HashMap<String, String>>> gattCharacteristicData
= new ArrayList<ArrayList<HashMap<String, String>>>();
ArrayList<HashMap<String, String>> gattServiceData1 = new ArrayList<HashMap<String, String>>();
ArrayList<ArrayList<HashMap<String, String>>> gattCharacteristicData1
= new ArrayList<ArrayList<HashMap<String, String>>>();
private BluetoothGattCharacteristic mNotifyCharacteristic;
private BluetoothGattCharacteristic mNotifyCharacteristic1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mHandler = new Handler();
// Use this check to determine whether BLE is supported on the device. Then you can
// selectively disable BLE-related features.
if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
finish();
}
// Initializes a Bluetooth adapter. For API level 18 and above, get a reference to
// BluetoothAdapter through BluetoothManager.
final BluetoothManager bluetoothManager =
(BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
mBluetoothAdapter = bluetoothManager.getAdapter();
// Checks if Bluetooth is supported on the device.
if (mBluetoothAdapter == null) {
Toast.makeText(this, R.string.error_bluetooth_not_supported, Toast.LENGTH_SHORT).show();
finish();
return;
}
addressID.add("20:CD:39:87:DC:AA");
addressID.add("20:CD:39:87:DF:82");
}
@Override
protected void onResume() {
super.onResume();
Log.e(TAG, "onResume");
// Ensures Bluetooth is enabled on the device. If Bluetooth is not currently enabled,
// fire an intent to display a dialog asking the user to grant permission to enable it.
if (!mBluetoothAdapter.isEnabled()) {
if (!mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
}
}
scanLeDevice(true);
if (mBluetoothLeService != null) {
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// User chose not to enable Bluetooth.
if (requestCode == REQUEST_ENABLE_BT && resultCode == Activity.RESULT_CANCELED) {
finish();
return;
}
super.onActivityResult(requestCode, resultCode, data);
}
@Override
protected void onPause() {
super.onPause();
scanLeDevice(false);
unregisterReceiver(mGattUpdateReceiver);
unregisterReceiver(mGattUpdateReceiver1);
}
@Override
protected void onDestroy() {
super.onDestroy();
unbindService(mServiceConnection);
mBluetoothLeService = null;
mBluetoothLeService1 = null;
}
private void scanLeDevice(final boolean enable) {
if (enable) {
Log.e(TAG, "scanLeDevice true");
// Stops scanning after a pre-defined scan period.
mHandler.postDelayed(new Runnable() {
@Override
public void run() {
mScanning = false;
mBluetoothAdapter.stopLeScan(mLeScanCallback);
invalidateOptionsMenu();
}
}, SCAN_PERIOD);
mScanning = true;
mBluetoothAdapter.startLeScan(mLeScanCallback);
} else {
Log.e(TAG, "scanLeDevice false");
mScanning = false;
mBluetoothAdapter.stopLeScan(mLeScanCallback);
}
invalidateOptionsMenu();
}
// Device scan callback.
private BluetoothAdapter.LeScanCallback mLeScanCallback =
new BluetoothAdapter.LeScanCallback() {
@Override
public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
runOnUiThread(new Runnable() {
@Override
public void run() {
deviceList.add(device);
Log.e(TAG, "deviceList count = " + deviceList.size());
if(deviceList.size() >= 2){
checkDevices();
}
}
});
}
};
private void checkDevices() {
Intent gattServiceIntent = new Intent(this, BluetoothLeService.class);
bindService(gattServiceIntent, mServiceConnection, BIND_AUTO_CREATE);
Intent gattServiceIntent1 = new Intent(this, BluetoothLeService.class);
bindService(gattServiceIntent1, mServiceConnection1, BIND_AUTO_CREATE);
registerReceiver(mGattUpdateReceiver, makeGattUpdateIntentFilter());
registerReceiver(mGattUpdateReceiver1, makeGattUpdateIntentFilter());
}
//TODO -- connect functions here
private static IntentFilter makeGattUpdateIntentFilter() {
final IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(BluetoothLeService.ACTION_GATT_CONNECTED);
intentFilter.addAction(BluetoothLeService.ACTION_GATT_DISCONNECTED);
intentFilter.addAction(BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED);
intentFilter.addAction(BluetoothLeService.ACTION_DATA_AVAILABLE);
return intentFilter;
}
// Code to manage Service lifecycle.
private final ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder service) {
mBluetoothLeService = ((BluetoothLeService.LocalBinder) service).getService();
if (!mBluetoothLeService.initialize()) {
Log.e(TAG, "Unable to initialize Bluetooth");
finish();
}
Log.e(TAG, "connecting to " + deviceList.get(0).getAddress());
mBluetoothLeService.connect("20:CD:39:87:DC:AA");
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mBluetoothLeService = null;
}
};
private final ServiceConnection mServiceConnection1 = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder service) {
mBluetoothLeService1 = ((BluetoothLeService.LocalBinder) service).getService();
if (!mBluetoothLeService1.initialize()) {
Log.e(TAG, "1Unable to initialize Bluetooth");
finish();
}
// Automatically connects to the device upon successful start-up initialization.
Log.e(TAG, "1connecting to " + deviceList.get(1).getAddress());
mBluetoothLeService1.connect("20:CD:39:87:DF:82");
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mBluetoothLeService = null;
}
};
private final BroadcastReceiver mGattUpdateReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (BluetoothLeService.ACTION_GATT_CONNECTED.equals(action)) {
Log.e(TAG, "connected");
} else if (BluetoothLeService.ACTION_GATT_DISCONNECTED.equals(action)) {
Log.e(TAG, "disconnected");
mConnected = false;
} else if (BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
// Show all the supported services and characteristics on the user interface.
Log.e(TAG, "gatt services discovered");
displayGattServices(mBluetoothLeService.getSupportedGattServices());
} else if (BluetoothLeService.ACTION_DATA_AVAILABLE.equals(action)) {
Log.e(TAG, "data available");
String data = intent.getStringExtra(BluetoothLeService.EXTRA_DATA);
Log.e(TAG, "data is = " + data);
}
}
};
private final BroadcastReceiver mGattUpdateReceiver1 = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (BluetoothLeService.ACTION_GATT_CONNECTED.equals(action)) {
Log.e(TAG, "1connected");
} else if (BluetoothLeService.ACTION_GATT_DISCONNECTED.equals(action)) {
Log.e(TAG, "1disconnected");
mConnected = false;
} else if (BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
// Show all the supported services and characteristics on the user interface.
Log.e(TAG, "1gatt services discovered");
displayGattServices1(mBluetoothLeService1.getSupportedGattServices());
} else if (BluetoothLeService.ACTION_DATA_AVAILABLE.equals(action)) {
Log.e(TAG, "1data available");
String data = intent.getStringExtra(BluetoothLeService.EXTRA_DATA);
Log.e(TAG, "1data is = " + data);
}
}
};
private void displayGattServices(List<BluetoothGattService> gattServices) {
if (gattServices == null) return;
Log.e(TAG, "display gatt services not null.");
String uuid = null;
String unknownServiceString = getResources().getString(R.string.unknown_service);
String unknownCharaString = getResources().getString(R.string.unknown_characteristic);
mGattCharacteristics = new ArrayList<ArrayList<BluetoothGattCharacteristic>>();
// Loops through available GATT Services.
for (BluetoothGattService gattService : gattServices) {
HashMap<String, String> currentServiceData = new HashMap<String, String>();
uuid = gattService.getUuid().toString();
currentServiceData.put(
LIST_NAME, SampleGattAttributes.lookup(uuid, unknownServiceString));
currentServiceData.put(LIST_UUID, uuid);
gattServiceData.add(currentServiceData);
ArrayList<HashMap<String, String>> gattCharacteristicGroupData =
new ArrayList<HashMap<String, String>>();
List<BluetoothGattCharacteristic> gattCharacteristics =
gattService.getCharacteristics();
ArrayList<BluetoothGattCharacteristic> charas =
new ArrayList<BluetoothGattCharacteristic>();
// Loops through available Characteristics.
for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
charas.add(gattCharacteristic);
HashMap<String, String> currentCharaData = new HashMap<String, String>();
uuid = gattCharacteristic.getUuid().toString();
currentCharaData.put(
LIST_NAME, SampleGattAttributes.lookup(uuid, unknownCharaString));
currentCharaData.put(LIST_UUID, uuid);
gattCharacteristicGroupData.add(currentCharaData);
if(uuid.equals(SampleGattAttributes.DOG_CHARACTERISTIC_CONFIG)){
Log.e(TAG, "uuid characteristic detected");
final int charaProp = gattCharacteristic.getProperties();
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_READ) > 0) {
Log.e(TAG, "gatt characteristics read!");
// If there is an active notification on a characteristic, clear
// it first so it doesn't update the data field on the user interface.
if (mNotifyCharacteristic != null) {
mBluetoothLeService.setCharacteristicNotification(
mNotifyCharacteristic, false);
mNotifyCharacteristic = null;
}
mBluetoothLeService.readCharacteristic(gattCharacteristic);
}
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_NOTIFY) > 0) {
Log.e(TAG, "gatt characteristics notify!");
mNotifyCharacteristic = gattCharacteristic;
mBluetoothLeService.setCharacteristicNotification(
gattCharacteristic, true);
}
}
}
mGattCharacteristics.add(charas);
gattCharacteristicData.add(gattCharacteristicGroupData);
}
}
private void displayGattServices1(List<BluetoothGattService> gattServices) {
if (gattServices == null) return;
Log.e(TAG, "1display gatt services not null.");
String uuid = null;
String unknownServiceString = getResources().getString(R.string.unknown_service);
String unknownCharaString = getResources().getString(R.string.unknown_characteristic);
mGattCharacteristics1 = new ArrayList<ArrayList<BluetoothGattCharacteristic>>();
// Loops through available GATT Services.
for (BluetoothGattService gattService : gattServices) {
HashMap<String, String> currentServiceData = new HashMap<String, String>();
uuid = gattService.getUuid().toString();
currentServiceData.put(
LIST_NAME, SampleGattAttributes.lookup(uuid, unknownServiceString));
currentServiceData.put(LIST_UUID, uuid);
gattServiceData1.add(currentServiceData);
ArrayList<HashMap<String, String>> gattCharacteristicGroupData =
new ArrayList<HashMap<String, String>>();
List<BluetoothGattCharacteristic> gattCharacteristics =
gattService.getCharacteristics();
ArrayList<BluetoothGattCharacteristic> charas =
new ArrayList<BluetoothGattCharacteristic>();
// Loops through available Characteristics.
for (BluetoothGattCharacteristic gattCharacteristic : gattCharacteristics) {
charas.add(gattCharacteristic);
HashMap<String, String> currentCharaData = new HashMap<String, String>();
uuid = gattCharacteristic.getUuid().toString();
currentCharaData.put(
LIST_NAME, SampleGattAttributes.lookup(uuid, unknownCharaString));
currentCharaData.put(LIST_UUID, uuid);
gattCharacteristicGroupData.add(currentCharaData);
if (uuid.equals(SampleGattAttributes.DOG_CHARACTERISTIC_CONFIG)) {
Log.e(TAG, "1uuid characteristic detected");
final int charaProp = gattCharacteristic.getProperties();
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_READ) > 0) {
Log.e(TAG, "1gatt characteristics read!");
// If there is an active notification on a characteristic, clear
// it first so it doesn't update the data field on the user interface.
if (mNotifyCharacteristic1 != null) {
mBluetoothLeService1.setCharacteristicNotification(
mNotifyCharacteristic1, false);
mNotifyCharacteristic1 = null;
}
mBluetoothLeService1.readCharacteristic(gattCharacteristic);
}
if ((charaProp | BluetoothGattCharacteristic.PROPERTY_NOTIFY) > 0) {
Log.e(TAG, "1gatt characteristics notify!");
mNotifyCharacteristic1 = gattCharacteristic;
mBluetoothLeService1.setCharacteristicNotification(
gattCharacteristic, true);
}
}
}
mGattCharacteristics1.add(charas);
gattCharacteristicData1.add(gattCharacteristicGroupData);
}
}
}
What I do is that once I get the 2 addresses that I want to connect to, I initialize all the necessary connections, services, and broadcast receivers. However, the bluetoothLeGatt messages I receive are the same. Depending on it connected to the Dog or Cat block, I'd get the lines:
data = dog
1data = dog
From the LogCat. It seems as if they were connected to the same device.
I checked my code and I even hardcoded the addresses in but to no avail.
Solution 1:[1]
I've made a connection with multiple devices and it works fine. I also made one Service for scanning and one for each ble communication.
Make sure not to use bound services for the communication part because the disconnection might be a problem (it was in my case).
For the Scanning part I made a List of Strings with the Mac addresses in it. When I found one device in my scanner I send the device via broadcastreceiver to my main activity and there I transmit it to its service. So every connection runs in its own service with its own broadcastreceiver and filtersettings.
To make sure that it's not a problem of your broadcastreceiver, make a console log in each service where you display the output immediately. I doubt that your device has two connections to the same server.
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | Danielle |