Android ble cannot receive GATT feature notifications from the device
•
Android
When I write a value on a feature, I'm trying to receive a notification from the device, but I don't receive anything. I enable notification about the feature, and then I write the value. I've seen that the feature in the device has changed its value, but I can't get notification. This is my code:
DeviceActivity：
public class DevicesActivity extends Activity {
private BLEService mBluetoothLeService;
private String mDeviceAddress;
private boolean mConnected = false;
private BluetoothGattCharacteristic mNotifyCharacteristic;
private final ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder service) {
mBluetoothLeService = ((BLEService.LocalBinder) service).getService();
if (!mBluetoothLeService.initialize()) {
finish();
}
mBluetoothLeService.context = DevicesActivity.this;
mBluetoothLeService.connect(mDeviceAddress);
}
@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 (BLEService.ACTION_GATT_CONNECTED.equals(action)) {
mConnected = true;
invalidateOptionsMenu();
} else if (BLEService.ACTION_GATT_DISCONNECTED.equals(action)) {
mConnected = false;
invalidateOptionsMenu();
} else if (BLEService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
List<BluetoothGattService> servicesList;
servicesList = mBluetoothLeService.getSupportedGattServices();
Iterator<BluetoothGattService> iter = servicesList.iterator();
while (iter.hasNext()) {
BluetoothGattService bService = (BluetoothGattService) iter.next();
if (bService.getUuid().toString().equals(BLEUUID.SERVICE)){
mService = bService;
}
}
} else if (BLEService.ACTION_DATA_AVAILABLE.equals(action)) {
displayData(intent.getStringExtra(BLEService.EXTRA_DATA));
}
}
};
private static final String TAG = "BLEDevice";
public static final String EXTRA_BLUETOOTH_DEVICE = "BT_DEVICE";
private BluetoothAdapter mBTAdapter;
private BluetoothDevice mDevice;
private BluetoothGatt mConnGatt;
private int mStatus;
BluetoothGattService mService;
private EditText pinTxt;
private Button cancelBtn;
private Button unlockBtn;
private Button changePinBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
setContentView(R.layout.activity_devices);
pinTxt = (EditText) findViewById(R.id.pin_txt);
cancelBtn = (Button) findViewById(R.id.cancel_btn);
unlockBtn = (Button) findViewById(R.id.unlock_btn);
changePinBtn = (Button) findViewById(R.id.change_pin_btn);
unlockBtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String aux = pinTxt.getText().toString();
mBluetoothLeService.sendCharacteristic(aux, getBTDeviceExtra());
}
});
mDevice = getBTDeviceExtra();
mDeviceAddress = mDevice.getAddress();
if (mServiceConnection == null){
Log.v("NULL", "mServiceConnection NULL");
}
Intent gattServiceIntent = new Intent(this, BLEService.class);
if (gattServiceIntent==null){
Log.v("NULL", "mServiceConnection NULL");
}
bindService(gattServiceIntent, mServiceConnection, BIND_AUTO_CREATE);
mStatus = BluetoothProfile.STATE_DISCONNECTED;
}
private void displayData(String data) {
if (data != null) {
Toast.makeText(DevicesActivity.this, data, Toast.LENGTH_LONG);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
unbindService(mServiceConnection);
mBluetoothLeService = null;
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(mGattUpdateReceiver);
}
private static IntentFilter makeGattUpdateIntentFilter() {
final IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(BLEService.ACTION_GATT_CONNECTED);
intentFilter.addAction(BLEService.ACTION_GATT_DISCONNECTED);
intentFilter.addAction(BLEService.ACTION_GATT_SERVICES_DISCOVERED);
intentFilter.addAction(BLEService.ACTION_DATA_AVAILABLE);
return intentFilter;
}
@Override
protected void onResume() {
super.onResume();
registerReceiver(mGattUpdateReceiver, makeGattUpdateIntentFilter());
if (mBluetoothLeService != null) {
final boolean result = mBluetoothLeService.connect(mDeviceAddress);
}
}
private BluetoothDevice getBTDeviceExtra() {
Intent intent = getIntent();
if (intent
== null) { return null;
}
Bundle extras = intent.getExtras();
if (extras == null) {
return null;
}
BluetoothDevice aux = extras.getParcelable(EXTRA_BLUETOOTH_DEVICE);
return aux;
}
BLEService：
private final BluetoothGattCallback mGattCallback = new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
String intentAction;
if (newState == BluetoothProfile.STATE_CONNECTED) {
intentAction = ACTION_GATT_CONNECTED;
mConnectionState = STATE_CONNECTED;
broadcastUpdate(intentAction);
Log.i(TAG, "Connected to GATT server.");
// Attempts to discover services after successful connection.
Log.i(TAG, "Attempting to start service discovery:" +
mBluetoothGatt.discoverServices());
} else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
intentAction = ACTION_GATT_DISCONNECTED;
mConnectionState = STATE_DISCONNECTED;
Log.i(TAG, "Disconnected from GATT server.");
broadcastUpdate(intentAction);
}
}
@Override
public void onServicesDiscovered(BluetoothGatt gatt, int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
for (BluetoothGattService service : gatt.getServices()) {
if ((service == null) || (service.getUuid() == null)) {
continue;
}
if (BLEUUID.SERVICE.equalsIgnoreCase(service.getUuid().toString())) {
mService = service;
}
}
broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
} else {
Log.w(TAG, "onServicesDiscovered received: " + status);
}
}
@Override
public void onCharacteristicRead(BluetoothGatt gatt,BluetoothGattCharacteristic characteristic,int status) {
if (status == BluetoothGatt.GATT_SUCCESS) {
broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
broadcastUpdate(EXTRA_DATA, characteristic);
Log.i("CARAC","CARACTERISTICA LEIDA onCharacteristicRead()");
}
}
@Override
public void onCharacteristicChanged(BluetoothGatt gatt,BluetoothGattCharacteristic characteristic) {
readCharacteristic(characteristic);
broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
Log.i("CARAC","CAMBIO EN CARACTERISTICA");
}
};
private void broadcastUpdate(final String action) {
final Intent intent = new Intent(action);
sendBroadcast(intent);
}
@TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
private void broadcastUpdate(final String action,final BluetoothGattCharacteristic characteristic) {
final Intent intent = new Intent(action);
if (PIN_CHARACTERISTIC.equals(characteristic.getUuid())) {
final String pin = characteristic.getStringValue(0);
intent.putExtra(EXTRA_DATA, String.valueOf(pin));
} else {
// For all other profiles, writes the data formatted in HEX.
final byte[] data = characteristic.getValue();
if (data != null && data.length > 0) {
final StringBuilder stringBuilder = new StringBuilder(data.length);
for(byte byteChar : data)
stringBuilder.append(String.format("%02X ", byteChar));
Log.i("RECIBIDO", "RECIBIDOS DATOS");
intent.putExtra(EXTRA_DATA, new String(data) + "\n" + stringBuilder.toString());
}
}
sendBroadcast(intent);
}
public class LocalBinder extends Binder {
BLEService getService() {
return BLEService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
@Override
public boolean onUnbind(Intent intent) {
// After using a given device, you should make sure that BluetoothGatt.close() is called
// such that resources are cleaned up properly. In this particular example, close() is
// invoked when the UI is disconnected from the Service.
close();
return super.onUnbind(intent);
}
private final IBinder mBinder = new LocalBinder();
public boolean initialize() {
if (mBluetoothManager == null) {
mBluetoothManager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
if (mBluetoothManager == null) {
return false;
}
}
mBluetoothAdapter = mBluetoothManager.getAdapter();
if (mBluetoothAdapter == null) {
return false;
}
return true;
}
public boolean connect(final String address) {
if (mBluetoothAdapter == null || address == null) {
return false;
}
// PrevIoUsly connected device. Try to reconnect.
if (mBluetoothDeviceAddress != null && address.equals(mBluetoothDeviceAddress)
&& mBluetoothGatt != null) {
if (mBluetoothGatt.connect()) {
mConnectionState = STATE_CONNECTING;
return true;
} else {
return false;
}
}
final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
if (device == null) {
return false;
}
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
mBluetoothDeviceAddress = address;
mConnectionState = STATE_CONNECTING;
return true;
}
public void disconnect() {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
return;
}
mBluetoothGatt.disconnect();
}
public void close() {
if (mBluetoothGatt == null) {
return;
}
mBluetoothGatt.close();
mBluetoothGatt = null;
Log.e("CIERRE", "CONEXION CERRADA");
}
public void readCharacteristic(BluetoothGattCharacteristic characteristic) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
return;
}
mBluetoothGatt.readCharacteristic(characteristic);
Log.i("READ", "CARACTERISTICA LEIDA");
}
public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic, boolean enabled) {
if (mBluetoothAdapter == null || mBluetoothGatt == null) {
return;
}
mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);
if (PIN_CHARACTERISTIC.equals(characteristic.getUuid())){
BluetoothGattDescriptor descriptor =
new BluetoothGattDescriptor(UUID.nameUUIDFromBytes(BLEUUID.PIN_CHARACTERISTIC_CONfig_DESCRIPTOR.getBytes()),
BluetoothGattDescriptor.PERMISSION_WRITE_SIGNED);
descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
mBluetoothGatt.writeDescriptor(descriptor);
}
}
public List<BluetoothGattService> getSupportedGattServices() {
if (mBluetoothGatt == null) return null;
return mBluetoothGatt.getServices();
}
public void sendCharacteristic(String pin, BluetoothDevice device){
byte[] pinByte = pin.getBytes();
int pinInt = Integer.valueOf(pin);
BluetoothGattCharacteristic ch = (BluetoothGattCharacteristic) mService.getCharacteristic(UUID
.fromString(BLEUUID.PIN_CHARACTERISTIC_UUID));
ch.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
ch.setValue(pin);
Toast.makeText(context, "CARACTERISTICA ASIGNADA", Toast.LENGTH_SHORT).show();
connect(device.getAddress());
mBluetoothGatt = device.connectGatt(this, false, mGattCallback);
setCharacteristicNotification(ch, true);
if (mBluetoothGatt.writeCharacteristic(ch)) {
Toast.makeText(context, "CARACTERISTICA ESCRITA", Toast.LENGTH_SHORT).show();
}
}
}
BLEUUID
public class BLEUUID {
// CARACTERISTICA PIN
public static final String SERVICE ="0000fff0-0000-1000-8000-00805f9b34fb";
public static final String PIN_CHARACTERISTIC_UUID="0000fff9-0000-1000-8000-00805f9b34fb";
public static final String PIN_CHARACTERISTIC_CONfig_DESCRIPTOR="0x2902";
private static HashMap<String, String> attributes = new HashMap();
static {
attributes.put(SERVICE, "Service");
attributes.put(PIN_CHARACTERISTIC_UUID, "Pin");
}
Oncharacteristicchange () never executes when I debug
Someone knows what the problem is
resolvent:
The following are the general modes required to use ble on Android:
>You try to connect > you get a callback indicating that it is connected > you discover the service > you are told that the service is discovered > you get the feature > for each feature, you can get the descriptor > for the descriptor, you set it to use bluetoothgattdescriptor. Setvalue() to enable notification / Instruction > you use bluetoothgatt. Writedescriptor() Write descriptor > you can use Bluetooth GATT. Setcharacteristicnotification() to enable feature notification locally. Without this, you will not be recalled. > you receive notification that the descriptor has been written > now you can write data to the feature. All feature and descriptor configurations are completed before writing anything to any feature
The content of this article comes from the network collection of netizens. It is used as a learning reference. The copyright belongs to the original author.
THE END
二维码