1
votes

i am currently using RxAndroidBle to write a firmware to a bluetooth device. The way it works i have to send chunks (580 bytes per chunk) of data to the bluetooth device on one WRITE_CHARACTERISTIC_UUID and then listen to the result on a LISTEN_CHARACTERISTIC_UUID to check if the bluetooth device has successfully acknowledged the chunk.

Ideally I want this write and notify chain to be one operation so i am using this code from a similar stack overflow question (https://stackoverflow.com/a/41140523/734385):

private byte[] writeData(byte[] _payload) {
    return mBleConnection
            .flatMap( // when the connection is available...
                    rxBleConnection -> rxBleConnection.setupNotification(LISTEN_UUID), // ... setup the notification...
                    (rxBleConnection, apScanDataNotificationObservable) -> Observable.combineLatest( // ... when the notification is setup...
                            rxBleConnection.createNewLongWriteBuilder().setBytes(_payload).setCharacteristicUuid(WRITE_UUID).setMaxBatchSize(20).build(),
                            apScanDataNotificationObservable.first(), // ... and observe for the first notification on the AP_SCAN_DATA
                            (writtenBytes, responseBytes) -> responseBytes // ... when both will appear return just the response bytes...
                    )
            )
            .flatMap(observable -> observable) // ... flatMap the result as it is Observable<byte[]>...
            .toBlocking()
            .first(); // ... and finish after first response is received to cleanup notifications
}

The issue is that this works only the first few times, afterwards the write operation succeeds but I am never notified. This is the log for the last few chunks before it stops:

02-23 08:46:33.765 2864-5256/com.company.android.ble I/BLE_FW_WRITE: [FW_CHUNK_24] starting
02-23 08:46:33.772 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(182789785)
02-23 08:46:33.772 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(182789785)
02-23 08:46:33.773 2864-5256/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: true
02-23 08:46:33.777 2864-5256/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(22527736)
02-23 08:46:33.910 2864-2888/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:33.912 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(182789785)
02-23 08:46:33.912 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(22527736)
02-23 08:46:34.055 2864-3032/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:34.059 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationCharacteristicLongWrite(71420405)
02-23 08:46:34.063 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(22527736)
02-23 08:46:34.063 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationCharacteristicLongWrite(71420405)
02-23 08:46:34.067 2864-3093/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
<more onCharacteristicWrites here, but omitted due to max post length>
02-23 08:46:34.204 2864-3032/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
02-23 08:46:34.207 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationCharacteristicLongWrite(71420405)
02-23 08:46:35.041 2864-3093/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicChanged characteristic=69af0004-f994-3a57-749b-0e0aad3fca18
02-23 08:46:35.044 2864-5256/com.company.android.ble I/BLE_FW_WRITE: [FW_CHUNK_25] starting
02-23 08:46:35.044 2864-4250/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: false
02-23 08:46:35.048 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(183984640)
02-23 08:46:35.049 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(183984640)
02-23 08:46:35.053 2864-5256/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: true
02-23 08:46:35.060 2864-5256/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(71847163)
02-23 08:46:35.185 2864-3073/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:35.188 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(183984640)
02-23 08:46:35.189 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(71847163)
02-23 08:46:35.276 2864-2887/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:35.281 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationCharacteristicLongWrite(66222734)
02-23 08:46:35.283 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(71847163)
02-23 08:46:35.283 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationCharacteristicLongWrite(66222734)
02-23 08:46:35.287 2864-3032/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
<more onCharacteristicWrites here, but omitted due to max post length>
02-23 08:46:35.441 2864-3032/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
02-23 08:46:35.447 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationCharacteristicLongWrite(66222734)
02-23 08:46:36.298 2864-2975/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicChanged characteristic=69af0004-f994-3a57-749b-0e0aad3fca18
02-23 08:46:36.301 2864-4250/com.company.android.ble I/BLE_FW_WRITE: combine data for FW_CHUNK_25
02-23 08:46:36.303 2864-4250/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: false
02-23 08:46:36.303 2864-5256/com.company.android.ble D/SFlashRawWrite: msg length (total): 20, payload length: 3
02-23 08:46:36.303 2864-5256/com.company.android.ble D/SFlashRawWrite: msgId: -128
02-23 08:46:36.304 2864-5256/com.company.android.ble D/SFlashRawWrite: acked msg: 17 result: 1
02-23 08:46:36.304 2864-5256/com.company.android.ble I/BLE_TIMING: chunk 25 took 1260 ms
02-23 08:46:36.304 2864-5256/com.company.android.ble I/BLE_FW_WRITE: [FW_CHUNK_26] starting
02-23 08:46:36.313 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(248228237)
02-23 08:46:36.317 2864-5256/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: true
02-23 08:46:36.319 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(248228237)
02-23 08:46:36.321 2864-5256/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(164719036)
02-23 08:46:36.452 2864-2888/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:36.455 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(248228237)
02-23 08:46:36.456 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(164719036)
02-23 08:46:36.602 2864-3032/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:36.616 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationCharacteristicLongWrite(227542569)
02-23 08:46:36.623 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(164719036)
02-23 08:46:36.624 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationCharacteristicLongWrite(227542569)
02-23 08:46:36.632 2864-2975/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
<more onCharacteristicWrites here, but omitted due to max post length>
02-23 08:46:36.897 2864-2975/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
02-23 08:46:36.902 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationCharacteristicLongWrite(227542569)
02-23 08:46:37.563 2864-3093/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicChanged characteristic=69af0004-f994-3a57-749b-0e0aad3fca18
02-23 08:46:37.566 2864-5256/com.company.android.ble I/BLE_FW_WRITE: [FW_CHUNK_27] starting
02-23 08:46:37.567 2864-4250/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: false
02-23 08:46:37.569 2864-5256/com.company.android.ble D/BluetoothGatt: setCharacteristicNotification() - uuid: 69af0004-f994-3a57-749b-0e0aad3fca18 enable: true
02-23 08:46:37.572 2864-5256/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(150502697)
02-23 08:46:37.573 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(150502697)
02-23 08:46:37.574 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationDescriptorWrite(128172508)
02-23 08:46:37.711 2864-2888/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:37.715 2864-4250/com.company.android.ble D/RxBle#Radio:   QUEUED RxBleRadioOperationCharacteristicLongWrite(58981097)
02-23 08:46:37.730 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(150502697)
02-23 08:46:37.730 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationDescriptorWrite(128172508)
02-23 08:46:37.871 2864-3093/com.company.android.ble D/RxBle#BluetoothGatt: onDescriptorWrite descriptor=00002902-0000-1000-8000-00805f9b34fb status=0
02-23 08:46:37.876 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationDescriptorWrite(128172508)
02-23 08:46:37.879 2864-3150/com.company.android.ble D/RxBle#Radio:  STARTED RxBleRadioOperationCharacteristicLongWrite(58981097)
02-23 08:46:37.891 2864-3073/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
<more onCharacteristicWrites here, but omitted due to max post length>
02-23 08:46:38.126 2864-3073/com.company.android.ble D/RxBle#BluetoothGatt: onCharacteristicWrite characteristic=69af0003-f994-3a57-749b-0e0aad3fca18 status=0
02-23 08:46:38.128 2864-3150/com.company.android.ble D/RxBle#Radio: FINISHED RxBleRadioOperationCharacteristicLongWrite(58981097)

As you can see at the end I don't get a

onCharacteristicChanged characteristic=69af0004-f994-3a57-749b-0e0aad3fca18

at the end.

Note: the writeData is run in an Scheduler.io() Thread and the I am using the latest master commit (https://github.com/Polidea/RxAndroidBle/commit/37ecef5c270c792bcb9193f6dd76b8711642e0ff) from the library (as I need the new LongWriteBuilder)

Interestingly if I start an additionally "dummy" notification observable that does nothing:

mBleConnection
            .flatMap(rxBleConnection -> rxBleConnection.setupNotification(LISTEN_UUID))
            .flatMap(notificationObservable -> notificationObservable)
            .subscribe(Actions.empty(), Actions.empty())

the above observable works and I get every notification.

I suspect I am doing something wrong with the setup of the notification or I am missing a delay somewhere.

1

1 Answers

1
votes

There are two things:

  • The notifications are not guaranteed to be received - indications are

  • It seems that the Android OS is failing at repeatedly setting the notification off and on - judging from the log that the BluetoothGattCallback.onCharacteristicChanged() is not called.

Potential solution is to setup the notification before the start of the first writeData(byte[] _payload) and passing both the _payload and Observable<byte[]> so it would look like writeData(byte[] _payload, Observable<byte[]> listenCharacteristicNotifications). Then you could set the notification on the LISTEN_CHARACTERISTIC_UUID once and use it for each write.