Can not write or read to the device, crasch with Services have not been discovered for Peripheral(bluetoothDevice=XX:XX:X...

[arbonvata]

The code for scanning the device is

class ScanViewModel : ViewModel() {

    private val _advertisementList = MutableLiveData<Map<String, Advertisement>>()
    private val deviceMap: MutableMap<String, Advertisement> = mutableMapOf()
    val advertisementList = _advertisementList as LiveData<Map<String, Advertisement>>
    private val _stateLiveData = MutableLiveData<State>()


    private val _serviceDiscovered = MutableLiveData<Boolean>(false)
    val serviceDiscovered = _serviceDiscovered as LiveData<Boolean>

    var scanner: Scanner = Scanner {
        scanSettings = ScanSettings.Builder()
            .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
            .build()

        filters = listOf(Filter.Service(uuidFrom("6e400001-b5a3-f393-e0a9-e50e24dcca9e")))
    }

    init {
        viewModelScope.launch {
            scanner.advertisements.collect { advertisement: Advertisement ->
                if (
                    advertisement.name?.contains("APP Board") == false ||
                    advertisement.name?.contains("XYZ") == false
                ) {
                    if (!deviceMap.containsKey(advertisement?.identifier)) {
                        deviceMap.put(advertisement.identifier, advertisement)
                        _advertisementList.value = deviceMap
                    }
                }
            }
        }
    }

    fun connect(advertisement: Advertisement) {
        val peripheral = viewModelScope.peripheral(advertisement) {
            onServicesDiscovered {
                // requestMtu(512)
                _serviceDiscovered.value = true
                Log.d("MyTag", "onDiscoverServiced")
            }
            logging {
                level = Logging.Level.Data
            }
            transport = Transport.Le
            phy = Phy.Le1M
        }

        viewModelScope.launch {
            peripheral.connect()
            DataRepository.addDevice(advertisement)
            launch {
                peripheral.state.collect { state: State ->
                    Log.d("MyTag", state.toString())
                    _stateLiveData.value = state
                }
            }
        }
    }

}

and the code for navigating to "main" bluetoth screen is

viewModel.serviceDiscovered.observe(viewLifecycleOwner) {
            if (it) {
                findNavController().navigate(R.id.bluetoothFragment)
            }
        }`

The code for my BleDevice looks like this

class BleDevice(val advertisement: Advertisement) {
    val scope = CoroutineScope(Job() + Dispatchers.Main)
    val serviceUuid = "6e400001-b5a3-f393-e0a9-e50e24dcca9e"
    val readCharacteristicUuid = "6e400003-b5a3-f393-e0a9-e50e24dcca9e"
    val writeCharacteristicUuid = "6e400002-b5a3-f393-e0a9-e50e24dcca9e"
    private val _dataFlow = MutableSharedFlow<ByteArray>()
    val dataFlow = _dataFlow.asSharedFlow()

    private val readCharacteristic = characteristicOf(service = serviceUuid, characteristic = readCharacteristicUuid)
    private val writeCharacteristic = characteristicOf(service = serviceUuid, characteristic = writeCharacteristicUuid)
    private val peripheral: Peripheral = scope.peripheral(advertisement)

    suspend fun writeData(value: String) {

        peripheral.write(writeCharacteristic, value.toByteArray(), WriteType.WithResponse)
    }

    private suspend fun readData() {
        while (true) {
            val value = peripheral.read(readCharacteristic)
            _dataFlow.emit(value)
        }
    }
    fun initDevice() {
        scope.launch {
            delay(800)

            readData()
        }
    }
}

I can connect to the device but writing and/or reading leads to a crasch with following error message

12-25 12:32:22.938 14375 14375 E AndroidRuntime: FATAL EXCEPTION: main
12-25 12:32:22.938 14375 14375 E AndroidRuntime: Process: com.example.bluetoothexample, PID: 14375
12-25 12:32:22.938 14375 14375 E AndroidRuntime: java.lang.IllegalStateException: Services have not been discovered for Peripheral(bluetoothDevice=XX:XX:XX:XX:EA:24)
12-25 12:32:22.938 14375 14375 E AndroidRuntime: 	at com.juul.kable.BluetoothDeviceAndroidPeripheral.getDiscoveredServices(BluetoothDeviceAndroidPeripheral.kt:97)
12-25 12:32:22.938 14375 14375 E AndroidRuntime: 	at com.juul.kable.BluetoothDeviceAndroidPeripheral.read(BluetoothDeviceAndroidPeripheral.kt:285)
12-25 12:32:22.938 14375 14375 E AndroidRuntime: 	at com.example.bluetoothexample.bleCommunicate.BleDevice.readData(BleDevice.kt:32)

Any suggestion how i can solve this? I am using version 0.27.0 of the library

[twyatt]

What does the code look like around the initDevice call? I'm wondering if initDevice is being called prior to the connection being fully established?

[arbonvata]

Here is the some of the code

class BluetoothViewModel : ViewModel() {
    private val bleDevice = DataRepository.getFirstDevice()

    private val _bleData = MutableStateFlow<String?>(null)
    val bleData = _bleData.asStateFlow()

    init {
        bleDevice?.initDevice()
    }

    fun readData() {
        viewModelScope.launch {
            bleDevice?.dataFlow?.collect {
                val data = String(it)
                _bleData.value = data
                handleIncomingData(data)
            }
        }
    }

    fun writeData(value: String) {
        viewModelScope.launch {
            bleDevice?.writeData(value)
        }
    }

    private fun handleIncomingData(data: String) {
        data.let {
            Log.d("TAG", "data $data")
        }
    }
}

And here is the fragment

class BluetoothFragment : Fragment() {
    private val viewModel: BluetoothViewModel by viewModels<BluetoothViewModel>()
    private lateinit var binding: FragmentBluetoothBinding

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentBluetoothBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        observeLiveData()
        setupUserEvent()
    }

    private fun setupUserEvent() {
        binding.sendButton.setOnClickListener {
            val text = binding.bleCommand.text.toString()
            viewModel.writeData(text)
        }
    }

    private fun observeLiveData() {
        viewModel.bleData.observe(viewLifecycleOwner) {data:String? ->
            data?.let { 
                Log.d("TAG", "incoming data $it")
            }
        }
    }
}

and in scanning fragment before we start to read and write data we have

scanAdapter = ScanAdapter(advertisementList) {
            Log.d("TAG", "connect")
            // viewModel.stopScan()
            binding.rcView.isEnabled = false

            viewModel.connect(it)
        }
        binding.rcView.adapter = scanAdapter

viewModel.serviceDiscovered.observe(viewLifecycleOwner) {
            if (it) {
                binding.rcView.isEnabled = true
                findNavController().navigate(R.id.bluetoothFragment)
            }
        }

[twyatt]

Thanks for sharing the usage code, helps to provide a bigger picture of what you're trying to do.

Unfortunately, I can't quite assess what might be going wrong... Can you enable Kable logging (with level of Events, or Data if you don't have any sensitive I/O), and then share the logs leading up to the crash?

[arbonvata]

Here is the kable logs

---------------------------- PROCESS STARTED (11046) for package com.example.bluetoothexample ----------------------------
22023-12-28 18:17:53.984  2821-3462  BtGatt.ScanManager      com.android.bluetooth                D  configureFilterParamter() : onFoundTimeout | onLostTimeout | onFoundCount | numOfTrackingEntries | scanFilterRssiThreshold | trackableScanFilterRssiThreshold | matchMode
---------------------------- PROCESS STARTED (11046) for package com.example.bluetoothexample ----------------------------
2023-12-28 18:17:55.842 11046-11046 Kable/Scanner           com.example.bluetoothexample         I  Starting scan with 1 filter(s)
2023-12-28 18:17:55.875  2821-3462  BtGatt.ScanManager      com.android.bluetooth                D  configureFilterParamter() : onFoundTimeout | onLostTimeout | onFoundCount | numOfTrackingEntries | scanFilterRssiThreshold | trackableScanFilterRssiThreshold | matchMode
2023-12-28 18:17:57.124 11046-11046 Kable/Peripheral        com.example.bluetoothexample         I  D1:27:47:86:EA:24 Connecting
2023-12-28 18:17:57.311 11046-11104 Kable/Callback          com.example.bluetoothexample         D  D1:27:47:86:EA:24 onConnectionStateChange
                                                                                                    status: Success
                                                                                                    newState: Connected
2023-12-28 18:17:57.315 11046-11046 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 discoverServices
2023-12-28 18:17:57.924 11046-11104 Kable/Callback          com.example.bluetoothexample         D  D1:27:47:86:EA:24 onServicesDiscovered
                                                                                                    status: GATT_SUCCESS(0)
2023-12-28 18:17:57.930 11046-11046 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 Discovered 5 services
2023-12-28 18:17:57.937 11046-11046 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 Configuring characteristic observations
2023-12-28 18:17:57.938 11046-11046 Kable/Peripheral        com.example.bluetoothexample         I  D1:27:47:86:EA:24 Connected
2023-12-28 18:17:58.838 11046-11046 AndroidRuntime          com.example.bluetoothexample         E  FATAL EXCEPTION: main
                                                                                                    Process: com.example.bluetoothexample, PID: 11046
                                                                                                    java.lang.IllegalStateException: Services have not been discovered for Peripheral(bluetoothDevice=XX:XX:XX:XX:EA:24)
                                                                                                    	at com.juul.kable.BluetoothDeviceAndroidPeripheral.getDiscoveredServices(BluetoothDeviceAndroidPeripheral.kt:100)
                                                                                                    	at com.juul.kable.BluetoothDeviceAndroidPeripheral.read(BluetoothDeviceAndroidPeripheral.kt:250)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.readData(BleDevice.kt:34)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.access$readData(BleDevice.kt:16)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice$initDevice$1.invokeSuspend(BleDevice.kt:41)
                                                                                                    	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
                                                                                                    	at kotlinx.coroutines.DispatchedTaskKt.resume(DispatchedTask.kt:235)
                                                                                                    	at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:168)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:474)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:508)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl$default(CancellableContinuationImpl.kt:497)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeUndispatched(CancellableContinuationImpl.kt:595)
                                                                                                    	at kotlinx.coroutines.android.HandlerContext$scheduleResumeAfterDelay$$inlined$Runnable$1.run(Runnable.kt:19)
                                                                                                    	at android.os.Handler.handleCallback(Handler.java:958)
                                                                                                    	at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                                                    	at android.os.Looper.loopOnce(Looper.java:230)
                                                                                                    	at android.os.Looper.loop(Looper.java:319)
                                                                                                    	at android.app.ActivityThread.main(ActivityThread.java:8893)
                                                                                                    	at java.lang.reflect.Method.invoke(Native Method)
                                                                                                    	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:608)
                                                                                                    	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1103)
                                                                                                    	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@c684266, Dispatchers.Main]
2023-12-28 18:17:58.885  8079-8079  Dc.IafdService          com.samsung.android.lool             I  handleAppError, pkgName : com.example.bluetoothexample, userId : 0, errorType : 4, repeat : true component : com.juul.kable.BluetoothDeviceAndroidPeripheral.getDiscoveredServices(BluetoothDeviceAndroidPeripheral.kt:100)errorStack: java.lang.IllegalStateException: Services have not been discovered for Peripheral(bluetoothDevice=XX:XX:XX:XX:EA:24)
                                                                                                    	at com.juul.kable.BluetoothDeviceAndroidPeripheral.getDiscoveredServices(BluetoothDeviceAndroidPeripheral.kt:100)
                                                                                                    	at com.juul.kable.BluetoothDeviceAndroidPeripheral.read(BluetoothDeviceAndroidPeripheral.kt:250)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.readData(BleDevice.kt:34)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.access$readData(BleDevice.kt:16)
                                                                                                    	at com

Go
t same crasch on 3 different phones, pixel6, samsung Galaxy A53 5G and Xiaomi12

[twyatt]

I think the issue is that you're creating a Peripheral separate from the one you're using to connect with? (i.e. you should be calling read from the same peripheral object reference that you call connect on)

In your BleDevice class you create a peripheral, but I don't see anywhere that you would've called connect on that same peripheral object reference?

[arbonvata]

This works now, but i get next crashes, despite the fact that the result from output says that 6e400003-b5a3-f393-e0a9-e50e24dcca9e

D1:27:47:86:EA:24 read
service: 6e400001-b5a3-f393-e0a9-e50e24dcca9e
characteristic: 6e400003-b5a3-f393-e0a9-e50e24dcca9e

---------------------------- PROCESS STARTED (15600) for package com.example.bluetoothexample ----------------------------
2023-12-29 02:31:18.884 15600-15600 nativeloader            com.example.bluetoothexample         D  Configuring clns-4 for other apk /data/app/~~2_rQjbuDBOjrt3Rlebs7Ww==/com.example.bluetoothexample-0rZWyag31rQgvk-RNgdsbw==/base.apk. target_sdk_version=34, uses_libraries=, library_path=/data/app/~~2_rQjbuDBOjrt3Rlebs7Ww==/com.example.bluetoothexample-0rZWyag31rQgvk-RNgdsbw==/lib/arm64, permitted_path=/data:/mnt/expand:/data/user/0/com.example.bluetoothexample
2023-12-29 02:31:18.894 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V  Currently set values for:
2023-12-29 02:31:18.894 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V    angle_gl_driver_selection_pkgs=[]
2023-12-29 02:31:18.894 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V    angle_gl_driver_selection_values=[]
2023-12-29 02:31:18.894 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V  ANGLE GameManagerService for com.example.bluetoothexample: false
2023-12-29 02:31:18.895 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V  com.example.bluetoothexample is not listed in per-application setting
2023-12-29 02:31:18.895 15600-15600 GraphicsEnvironment     com.example.bluetoothexample         V  Neither updatable production driver nor prerelease driver is supported.
2023-12-29 02:31:18.916 15600-15619 DMABUFHEAPS             com.example.bluetoothexample         I  Using DMA-BUF heap named: vframe-secure
2023-12-29 02:31:18.931 15600-15600 AppCompatDelegate       com.example.bluetoothexample         D  Checking for metadata for AppLocalesMetadataHolderService : Service not found
2023-12-29 02:31:18.957 15600-15600 luetoothexample         com.example.bluetoothexample         W  Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (unsupported, reflection, allowed)
2023-12-29 02:31:18.957 15600-15600 luetoothexample         com.example.bluetoothexample         W  Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (unsupported, reflection, allowed)
2023-12-29 02:31:19.018 15600-15600 Compatibil...geReporter com.example.bluetoothexample         D  Compat change id reported: 237531167; UID 10261; state: DISABLED
2023-12-29 02:31:20.892 15600-15600 Arbon                   com.example.bluetoothexample         D  Version S
2023-12-29 02:31:20.894 15600-15600 Compatibil...geReporter com.example.bluetoothexample         D  Compat change id reported: 263076149; UID 10261; state: ENABLED
2023-12-29 02:31:20.906 15600-15600 WindowOnBackDispatcher  com.example.bluetoothexample         W  OnBackInvokedCallback is not enabled for the application.
                                                                                                    Set 'android:enableOnBackInvokedCallback="true"' in the application manifest.
2023-12-29 02:31:20.961 15600-15600 Kable/Scanner           com.example.bluetoothexample         I  Starting scan without filters
2023-12-29 02:31:20.961 15600-15600 BluetoothAdapter        com.example.bluetoothexample         D  isLeEnabled(): ON
2023-12-29 02:31:20.965 15600-15614 BluetoothLeScanner      com.example.bluetoothexample         D  onScannerRegistered() - status=0 scannerId=13 mScannerId=0
2023-12-29 02:31:21.017 15600-15600 ArbonV                  com.example.bluetoothexample         D  devices[Advertisement(address=D1:27:47:86:EA:24, name=APP Board 3.0(EA-24), rssi=-38, txPower=-2147483648)]
2023-12-29 02:31:21.033 15600-15600 Compatibil...geReporter com.example.bluetoothexample         D  Compat change id reported: 210923482; UID 10261; state: ENABLED
2023-12-29 02:31:21.052 15600-15600 ArbonV                  com.example.bluetoothexample         D  devices[Advertisement(address=D1:27:47:86:EA:24, name=APP Board 3.0(EA-24), rssi=-38, txPower=-2147483648), Advertisement(address=E7:3A:15:CA:B0:CF, name=XDR_APP3, rssi=-68, txPower=-2147483648)]
2023-12-29 02:31:22.855 15600-15600 TAG                     com.example.bluetoothexample         D  connect
2023-12-29 02:31:22.867 15600-15600 Compatibil...geReporter com.example.bluetoothexample         D  Compat change id reported: 265103382; UID 10261; state: ENABLED
2023-12-29 02:31:22.872 15600-15600 Kable/Peripheral        com.example.bluetoothexample         I  D1:27:47:86:EA:24 Connecting
2023-12-29 02:31:22.873 15600-15600 BluetoothGatt           com.example.bluetoothexample         D  connect() - device: XX:XX:XX:XX:EA:24, auto: false
2023-12-29 02:31:22.873 15600-15600 BluetoothGatt           com.example.bluetoothexample         D  registerApp()
2023-12-29 02:31:22.873 15600-15600 BluetoothGatt           com.example.bluetoothexample         D  registerApp() - UUID=488bca8a-92fa-440f-a5cc-fc7a29fbafea
2023-12-29 02:31:22.875 15600-15614 BluetoothGatt           com.example.bluetoothexample         D  onClientRegistered() - status=0 clientIf=6
2023-12-29 02:31:23.060 15600-15648 BluetoothGatt           com.example.bluetoothexample         D  onClientConnectionState() - status=0 clientIf=6 device=D1:27:47:86:EA:24
2023-12-29 02:31:23.063 15600-15646 Kable/Callback          com.example.bluetoothexample         D  D1:27:47:86:EA:24 onConnectionStateChange
                                                                                                    status: Success
                                                                                                    newState: Connected
2023-12-29 02:31:23.065 15600-15600 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 discoverServices
2023-12-29 02:31:23.067 15600-15646 BluetoothGatt           com.example.bluetoothexample         D  discoverServices() - device: XX:XX:XX:XX:EA:24
2023-12-29 02:31:23.599 15600-15648 BluetoothGatt           com.example.bluetoothexample         D  onConnectionUpdated() - Device=D1:27:47:86:EA:24 interval=6 latency=0 timeout=500 status=0
2023-12-29 02:31:23.818 15600-15648 BluetoothGatt           com.example.bluetoothexample         D  onSearchComplete() = Device=D1:27:47:86:EA:24 Status=0
2023-12-29 02:31:23.820 15600-15646 Kable/Callback          com.example.bluetoothexample         D  D1:27:47:86:EA:24 onServicesDiscovered
                                                                                                    status: GATT_SUCCESS(0)
2023-12-29 02:31:23.830 15600-15600 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 Discovered 5 services
2023-12-29 02:31:23.837 15600-15600 ArbonV                  com.example.bluetoothexample         D  onDiscoverServiced
2023-12-29 02:31:23.837 15600-15600 Kable/Peripheral        com.example.bluetoothexample         V  D1:27:47:86:EA:24 Configuring characteristic observations
2023-12-29 02:31:23.837 15600-15600 Kable/Peripheral        com.example.bluetoothexample         I  D1:27:47:86:EA:24 Connected
2023-12-29 02:31:23.900 15600-15648 BluetoothGatt           com.example.bluetoothexample         D  onConnectionUpdated() - Device=D1:27:47:86:EA:24 interval=36 latency=0 timeout=500 status=0
2023-12-29 02:31:24.125 15600-15657 ProfileInstaller        com.example.bluetoothexample         D  Installing profile for com.example.bluetoothexample
2023-12-29 02:31:24.733 15600-15600 Kable/Peripheral        com.example.bluetoothexample         D  D1:27:47:86:EA:24 read
                                                                                                    service: 6e400001-b5a3-f393-e0a9-e50e24dcca9e
                                                                                                    characteristic: 6e400003-b5a3-f393-e0a9-e50e24dcca9e
2023-12-29 02:31:24.813 15600-15600 AndroidRuntime          com.example.bluetoothexample         E  FATAL EXCEPTION: main
                                                                                                    Process: com.example.bluetoothexample, PID: 15600
                                                                                                    java.util.NoSuchElementException: Characteristic 6e400003-b5a3-f393-e0a9-e50e24dcca9e with read property not found
                                                                                                    	at com.juul.kable.ProfileKt.obtain-vK39g5o(Profile.kt:146)
                                                                                                    	at com.juul.kable.BluetoothDeviceAndroidPeripheral.read(BluetoothDeviceAndroidPeripheral.kt:250)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.readData(BleDevice.kt:36)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice.access$readData(BleDevice.kt:17)
                                                                                                    	at com.example.bluetoothexample.bleCommunicate.BleDevice$initDevice$1.invokeSuspend(BleDevice.kt:61)
                                                                                                    	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
                                                                                                    	at kotlinx.coroutines.DispatchedTaskKt.resume(DispatchedTask.kt:235)
                                                                                                    	at kotlinx.coroutines.DispatchedTaskKt.dispatch(DispatchedTask.kt:168)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.dispatchResume(CancellableContinuationImpl.kt:474)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl(CancellableContinuationImpl.kt:508)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeImpl$default(CancellableContinuationImpl.kt:497)
                                                                                                    	at kotlinx.coroutines.CancellableContinuationImpl.resumeUndispatched(CancellableContinuationImpl.kt:595)
                                                                                                    	at kotlinx.coroutines.android.HandlerContext$scheduleResumeAfterDelay$$inlined$Runnable$1.run(Runnable.kt:19)
                                                                                                    	at android.os.Handler.handleCallback(Handler.java:958)
                                                                                                    	at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                                                    	at android.os.Looper.loopOnce(Looper.java:205)
                                                                                                    	at android.os.Looper.loop(Looper.java:294)
                                                                                                    	at android.app.ActivityThread.main(ActivityThread.java:8194)
                                                                                                    	at java.lang.reflect.Method.invoke(Native Method)
                                                                                                    	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:552)
                                                                                                    	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:971)
                                                                                                    	Suppressed: kotlinx.coroutines.internal.DiagnosticCoroutineContextException: [StandaloneCoroutine{Cancelling}@8c0eea6, Dispatchers.Main]
2023-12-29 02:31:24.827 15600-15600 Process                 com.example.bluetoothexample         I  Sending signal. PID: 15600 SIG: 9

Observe doesn't crash but read does :(

private suspend fun readData() {
        val value = peripheral.read(readCharacteristic)
        Log.d("TAG", "Reading ${String(value)}")
        _dataFlow.emit(value)
    }


    private suspend fun observeData() {
        val observation = peripheral.observe(readCharacteristic)
        observation.collect {
            _dataFlow.emit(it)
            Log.d("TAG", "Observing${String(it)}")
        }

    }

[twyatt]

It sounds like your peripheral's characteristic is not marked as being readable, so Kable is unable to find it for the read operation.

You can alternatively manually find the characteristic, see I/O section of documentation for details: https://github.com/JuulLabs/kable#io

Ideally you'd update your peripheral's firmware to have that characteristic marked as readable if that's the operation you're needing to perform.

[arbonvata]

Yes, i saw that this not readable, it has support for notifications only

[arbonvata]

Yes, i saw that this not readable, it has support for notificaion only. Thank you for all support