Android Programming - Getting Started with Bluetooth Low Energy - page 120

reliable way to know when notifications have been successfully enabled on the peer
device is to get the onDescriptorWrite() callback after the CCCD has been modified
and the GATT server has acknowledged the write operation. This example adds the
onDescriptorWrite() callback to this implementation of Application Accelerator in
the BleWrapper class , where it implements the BluetoothGattCallback code:
/* callbacks called for any action on particular Ble Device */
private final BluetoothGattCallback mBleCallback = new BluetoothGattCallback ()
{
...
// Added by Akiba
@Override
public void onDescriptorWrite ( BluetoothGatt gatt ,
BluetoothGattDescriptor descriptor ,
int status )
{
String deviceName = gatt . getDevice (). getName ();
String serviceName = BleNamesResolver . resolveServiceName ( \
descriptor . getCharacteristic (). getService (). getUuid (). \
toString (). toLowerCase ( Locale . getDefault ()));
String charName = BleNamesResolver . resolveCharacteristicName ( \
descriptor . getCharacteristic (). getUuid (). toString (). \
toLowerCase ( Locale . getDefault ()));
String description = "Device: " + deviceName + " Service: " \
+ serviceName + " Characteristic: " + charName ;
// we got response regarding our request to write new value to
// the characteristic, let's see if it failed or not
if ( status == BluetoothGatt . GATT_SUCCESS ) {
mUiCallback . uiSuccessfulWrite ( mBluetoothGatt , mBluetoothDevice ,
mBluetoothSelectedService ,
descriptor . getCharacteristic (),
description );
}
else {
mUiCallback . uiFailedWrite ( mBluetoothGatt , mBluetoothDevice ,
mBluetoothSelectedService ,
descriptor . getCharacteristic (),
description + " STATUS = " + status );
}
};
...
}
The onDescriptorWrite() method will then call Application Accelerator's uiSuccess
fulWrite() method if the notification was written properly.
You can enable notifications for all of the sensor characteristics in the same way you
enabled the sensors themselves, using a state machine to sequentially process one after