BLE 设备 writeCharacteristic 失败

Question

正在尝试从 BLE 血压设备获取数据。文档说每次连接设备时都必须同步 date/time。代码：

interactionSub = Observable.concat(  
        deviceConnection
                .writeCharacteristic( ReactiveBluetoothHelpers.DATE_TIME_CHARACTERISTIC_UUID, testDateTime )
                .doOnSubscribe(() -> Log.d(TAG, "doOnSubscribe called inside writeCharacteristic!"))
                .doOnError(Error -> Log.e(TAG, "doOnError called inside writeCharacteristic. " + Error.getMessage()))
                .doOnNext(bytes -> Log.d(TAG, "doOnNext called inside writeCharacteristic."))
                .delay( 500L, TimeUnit.MILLISECONDS )  
                .ignoreElements(), 
        deviceConnection
                .setupIndication( ReactiveBluetoothHelpers.BLOOD_PRESSURE_MEASUREMENT_UUID )
                .doOnNext( indicationObservable -> {
                    Log.d(TAG, "Blood Pressure measurement indication has been set up.");
                } )
                .flatMap(indicationObservable -> indicationObservable) // 
)  // end of concat
        .subscribe(
                this::handleBpMeasurement,
                this::handleBpMeasurementError
        );

设备已连接并已订阅，但尝试写入特性会导致错误。来自 BleDisconnectedException 的错误消息只是 "Disconnected from F4:5E:AB:10:DF:5C" 没有解释。

我无法想象这个错误是从哪里来的。我尝试编写的测试 date/time 具有年份（16 位小端）和其他 1 字节数量的有效值。

典型的日志序列：

12-04 15:47:46.617 16544-16612/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue:   QUEUED ConnectOperation(13884208)
12-04 15:47:46.618 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: unregisterApp() - mClientIf=8
12-04 15:47:46.621 16544-16565/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue: FINISHED DisconnectOperation(252854751)
12-04 15:47:46.624 16544-16565/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue:  STARTED ConnectOperation(13884208)
12-04 15:47:46.630 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: connect() - device: F4:5E:AB:10:DF:5C, auto: false
12-04 15:47:46.630 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: registerApp()
12-04 15:47:46.630 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: registerApp() - UUID=91617ce4-e91f-4117-acd4-95a1b2acbf29
12-04 15:47:46.633 16544-16575/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: onClientRegistered() - status=0 clientIf=8
12-04 15:47:47.042 16544-16575/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: onClientConnectionState() - status=0 clientIf=8 device=F4:5E:AB:10:DF:5C
12-04 15:47:47.043 16544-16575/com.calderadev.truecareccm.truecareservice D/RxBle#BluetoothGatt: onConnectionStateChange newState=2 status=0
12-04 15:47:47.044 16544-16575/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: onClientConnectionState() - status=62 clientIf=8 device=F4:5E:AB:10:DF:5C
12-04 15:47:47.044 16544-16575/com.calderadev.truecareccm.truecareservice D/RxBle#BluetoothGatt: onConnectionStateChange newState=0 status=62
12-04 15:47:47.045 16544-16575/com.calderadev.truecareccm.truecareservice I/RxBle#ConnectionOperationQueue: Connection operations queue to be terminated (F4:5E:AB:10:DF:5C)
12-04 15:47:47.047 16544-16565/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue: FINISHED ConnectOperation(13884208)
12-04 15:47:47.054 16544-16612/com.calderadev.truecareccm.truecareservice D/BPMonitor: We have connected to A&D_UA-651BLE_10DF5C with MAC F4:5E:AB:10:DF:5C
12-04 15:47:47.062 16544-16611/com.calderadev.truecareccm.truecareservice D/RxBle#Executors$RunnableAdapter: Terminated.
12-04 15:47:47.083 16544-16612/com.calderadev.truecareccm.truecareservice D/BPMonitor: doOnSubscribe called inside writeCharacteristic!
12-04 15:47:47.100 16544-16612/com.calderadev.truecareccm.truecareservice E/BPMonitor: doOnError called inside writeCharacteristic. Disconnected from F4:5E:AB:10:DF:5C
12-04 15:47:47.118 16544-16612/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue:   QUEUED DisconnectOperation(246198672)
12-04 15:47:47.120 16544-16565/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue:  STARTED DisconnectOperation(246198672)
12-04 15:47:47.121 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothManager: getConnectionState()
12-04 15:47:47.121 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothManager: getConnectedDevices
12-04 15:47:47.125 16544-16612/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue:   QUEUED ConnectOperation(589767105)
12-04 15:47:47.125 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: close()
12-04 15:47:47.127 16544-16571/com.calderadev.truecareccm.truecareservice D/BluetoothGatt: unregisterApp() - mClientIf=8
12-04 15:47:47.131 16544-16565/com.calderadev.truecareccm.truecareservice D/RxBle#ClientOperationQueue: FINISHED DisconnectOperation(246198672)

Answer 1

正如您在日志中看到的，onConnectionStateChange() 是通过 status=62 调用的，对应于 0x3E。 Android Sources 指向：

#define GATT_CONN_FAIL_ESTABLISH    HCI_ERR_CONN_FAILED_ESTABLISHMENT /* 0x03E connection fail to establish  */

所以似乎连接并没有真正建立在 OS 的较低层上，尽管它被报告为首先连接:

12-04 15:47:47.043 16544-16575/com.calderadev.truecareccm.truecareservice D/RxBle#BluetoothGatt: onConnectionStateChange newState=2 status=0
12-04 15:47:47.044 16544-16575/com.calderadev.truecareccm.truecareservice D/RxBle#BluetoothGatt: onConnectionStateChange newState=0 status=62

BLE 设备 writeCharacteristic 失败

BLE device writeCharacteristic failing

android

rx-java

android-bluetooth

rxandroidble