I need to update UI composable from bluetooth characteristic change.
Incoming data is:

@RequiresApi(Build.VERSION_CODES.TIRAMISU)
data class OrganConfig(
    var numberOfSetzers:Int=99,
    var manuals : MutableList<ManualConfig> = mutableListOf(  ManualConfig(keys = 32, name = "Pedal", valid=true),
                                                              ManualConfig(keys = 64, name = "Positif", valid=true)
    ),
    var valid:Boolean=false)

I have a modelView:

class OrganModel : ViewModel() {
...
     @RequiresApi(Build.VERSION_CODES.TIRAMISU)
    private val _organConfig = MutableStateFlow(OrganConfig())

    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
    val organConfig : StateFlow<OrganConfig> = _organConfig.asStateFlow()
...

    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
    private suspend fun parseData(dataInputStream: DataInputStream) : Optional<AbstractAnswer> =
            AbstractAnswer.checkHeader(dataInputStream)


    @RequiresApi(Build.VERSION_CODES.TIRAMISU)
    fun incomingAnswer(characteristic:BluetoothGattCharacteristic, value:ByteArray) {
        val ds = DataInputStream(ByteArrayInputStream(value))

        viewModelScope.launch(Dispatchers.IO) {
            val a = parseData(ds)
            if (a.isPresent) {
                val answer=a.get()
                withContext(Dispatchers.Main) {
                    when(answer) {
                        is ConfigAnswer -> {
                            _organConfig.update { cfg ->
                                cfg.copy(
                                    numberOfSetzers = answer.setzers.toInt(),
                                    manuals = answer.manuals,
                                    valid = true
                                )
                            }
                        }
                        ...
                        else -> Timber.w("Unknown answer $answer")
                    }
                }
            }
        }
    }
 
...
@RequiresApi(Build.VERSION_CODES.TIRAMISU)
    fun refresh() {
        _organConfig.update { cfg->
            cfg.copy(numberOfSetzers = 66)
        }
    }

}

I have an incoming event, when bluetooth characteristic changed like this:

  private val connectionEventListener by lazy {
        ConnectionEventListener().apply {

     ...
      onCharacteristicChanged={ _, characteristic, value ->
                organModel.incomingAnswer(characteristic, value)
      }

  }

Everything seems work, I see incoming values in logcat.

In my Composable:

@RequiresApi(Build.VERSION_CODES.TIRAMISU)
@SuppressLint("StateFlowValueCalledInComposition")
@Composable
fun OrganConfiguration(organModel: OrganModel, refreshClicked: () -> Unit) {

    val cfg by organModel.organConfig.collectAsState()

    Column(Modifier.fillMaxWidth()) {
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .padding(10.dp),
            horizontalArrangement = Arrangement.Center
        ) {
            Text(text = "Orgona konfiguráció")
        }
        Row(
            modifier = Modifier
                .fillMaxWidth()
                .padding(all = 8.dp),
            horizontalArrangement = Arrangement.Center
        ) {
            Box(
                Modifier
                    .weight(1f)
                    .padding(10.dp),
                Alignment.CenterStart
            ) {
                VerticalItem(
                    label = "Manuals",
                    value = cfg.manuals.size.toString()
                )
            }
            Box(
                Modifier
                    .weight(1f)
                    .padding(10.dp),
                Alignment.Center
            ) {
                VerticalItem(
                    label = "Registers",
                    value = cfg.numberOfSetzers.toString()
                )
            }
            Box(
                Modifier
                    .weight(1f)
                    .padding(10.dp),
                Alignment.CenterEnd
            ) {
                IconButton(
                    onClick = { refreshClicked() }) {
                    Icon(
                        Icons.Filled.Refresh, contentDescription = "refresh", tint = Color.Gray,
                        modifier = Modifier.size(48.dp)
                    )
                }
            }
        }
    }
}

I never see changes. But when I click refresh button to force changes in viewmodel I see the new values.

Bluetooth events are in background threads, it may be that should be the reason of not emitting statechage? How can I make update from bluetooth event thread?

thx,
Zamek