I want to read data from ble hardware continuously in android app via bluetooth.
Connection has done i can send data from app to ble but cant read data from ble.

`onCharactersticChanged` method has to be called when getting some data from ble but this callback method is not calling. and i'm trying to notify to ble but

```
writeChar.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_DEFAULT);
BluetoothGattDescriptor descriptor = new BluetoothGattDescriptor(BLEUtils.CLIENT_CHARACTERISTIC_CONFIG_UUID, BluetoothGattDescriptor.PERMISSION_WRITE_SIGNED);

descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);

gatt.writeDescriptor(descriptor);

```

---

```
  // Enable local notifications
        gatt.setCharacteristicNotification(writeChar, true);

```

---

```
 boolean succes = gatt.writeDescriptor(descriptor);

```

its returns `false`