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Send data from my App to Stm32 bluetooth Device - Kotlin

i have an application, and my application can connect to a bluetooth device.
After that, i want to send message (Int) to my Blutooth Low Energy device.
I have this code, but i can't figure it out what is the problem.
If you want i have : Characteristic UUID, Service UUID.
Really, i need your help...
I've edited the question :
My code :
val filter = IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED)
lateinit var bluetoothAdapter: BluetoothAdapter
val bluetoothManager = context.getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
bluetoothAdapter = bluetoothManager.adapter
settingViewModel.bluetooth(bluetoothAdapter = bluetoothAdapter)
val mReceiver: BroadcastReceiver = object : BroadcastReceiver() {
override fun onReceive(context: Context?, intent: Intent) {
val action = intent.action
if (action == BluetoothAdapter.ACTION_STATE_CHANGED) {
val state = intent.getIntExtra(
BluetoothAdapter.EXTRA_STATE,
BluetoothAdapter.ERROR
)
when (state) {
BluetoothAdapter.STATE_OFF -> {
settingViewModel.setIsConnected(false)
//settingViewModel.stopScan()
settingViewModel.setListDevices(null)
}
BluetoothAdapter.STATE_ON -> {
settingViewModel.setIsConnected(true)
//scan()
settingViewModel.setListDevices(bluetoothAdapter.bondedDevices)
context!!.unregisterReceiver(this)
}
}
}
}
}
context.registerReceiver(mReceiver, filter)
val SERVICE_UUID = "00000000-0001-11e1-9ab4-0002a5d5c51c"
val ConfigCharacteristic = descriptorOf(
service = SERVICE_UUID,
characteristic = "00E00000-0001-11e1-ac36-0002a5d5c51b",
descriptor = "00000000-0000-0000-0000-000000000000",
)
Button(
onClick = {
if (settingViewModel.isConnected.value == true) {
coroutine.launch(Dispatchers.IO) {
try {
settingViewModel.peripheral.write(ConfigCharacteristic, byteArrayOf(1))
} catch (e: Exception) {
Toast.makeText(context, e.message, Toast.LENGTH_SHORT).show()
}
}
}
// try {
// val Service =
// settingViewModel.deviceSocket.value.get .getService(UUID.fromString("0000ffe0-0000-1000-8000-00805f9b34fb"))
// val charac: BluetoothGattCharacteristic =
// Service.getCharacteristic(UUID.fromString("00E00000-0001-11e1-ac36-0002a5d5c51b"))
// settingViewModel.deviceSocket.value!!.outputStream.write("1".toByteArray())
// } catch (e: Exception) {
// Toast.makeText(context, e.message.toString(), Toast.LENGTH_LONG).show()
// }
}
) {
Text(text = "HelloWorld")
}
I Already have the mac adress, the caracteristic and the service UUID of the device i want to connect to.
Again, i really need your help

First of all:
When developing an app for a BLE device it is best to first use a generic BLE scanner app to test the connection and to find out which commands need to be sent. If you confirm that the BLE device works as expected you can continue with your own custom app. I would recommend nRF Connect for this task.
Regarding your problem:
There are still many things missing from your sourcecode. You said you can connect to the device but have problems sending a message. Your code does not contain anything related to a BLE connection so I can only assume that you connected to the device using the Bluetooth settings of your phone. This would be correct for Bluetooth Classic but BLE requires you to connect through your own custom app.
The Ultimate Guide to Android Bluetooth Low Energy explains all steps necessary for a successful BLE connection. These steps are:
Setting the correct permissions
Scan for nearby BLE devices
Connect to a BLE device of your choosing
Scan for Services
Read and Write a characteristic of your choosing
All these steps are explained in the Guide using Kotlin as programming language.

Using CompanionDeviceManager to read the devices information

I am using BluetoothLeScanner to scan for BLE devices and get a list of objects representing the devices to show inside my app (not connecting to any of them).
I am interested in doing the same, but using the CompanionDeviceManager now. Its callback CompanionDeviceManager.Callback.onDeviceFound(chooserLauncher: IntentSender?) unfortunately does not return any human readable form of found devices... the closest it gets is the IntentSender.writeToParcel method, but I am not sure how to use it in this situation.
I am not constrained to use the CompanionDeviceManager but I wanted to follow the OS version specific guidelines, we are supposed to use CompanionDeviceManager for Bluetooth devices scanning starting from API 26, but it seems useless in my case... so is there any way to get devices data from that callback, or should I just ditch it and stay with BluetoothLeScanner for all OS versions?

Late answer but it might help someone else. You can create a bluetooth device picker in combination with ActivityResultContracts.StartIntentSenderForResult() in order to get the BluetoothDevice. From there you will have access to all the device info that you need. Recent changes added some Android 12 permissions like android.permission.BLUETOOTH_CONNECT. Your mileage may vary.
val context = LocalContext.current
// Get the device manager instance
val deviceManager: CompanionDeviceManager by lazy {
ContextCompat.getSystemService(
context,
CompanionDeviceManager::class.java
) as CompanionDeviceManager
}
// Create a filter of your choice. Here I just look for specific device names
val deviceFilter: BluetoothDeviceFilter by lazy {
BluetoothDeviceFilter.Builder()
.setNamePattern(Pattern.compile(supportedDevices))
.build()
}
// Create a pairing request with your filter from the last step
val pairingRequest: AssociationRequest = AssociationRequest.Builder()
.addDeviceFilter(deviceFilter)
.build()
// Create a picker for discovered bluetooth devices
val bluetoothDevicePicker = rememberLauncherForActivityResult(
contract = ActivityResultContracts.StartIntentSenderForResult(),
onResult = {
val device: BluetoothDevice? =
it.data?.getParcelableExtra(CompanionDeviceManager.EXTRA_DEVICE)
try {
// Now that you have the desired device, do what you need to with it
device?.apply {
when {
name?.matches(Regex(firstDevicePattern)) == true -> {
Log.i(TAG, "${this.name} connected")
onFirstDeviceDiscovered(device)
}
name?.matches(Regex(secondDevicePattern)) == true -> {
Log.i(TAG, "${this.name} connected")
onSecondDeviceDiscovered(device)
}
}
}
} catch (e: SecurityException) {
e.printStackTrace()
//TODO: handle the security exception (this is possibly a bug)
// https://issuetracker.google.com/issues/198986283
}
}
)
// A utility function to centralize calling associate (optional)
val associateDevice: (AssociationRequest) -> Unit = { request ->
// Attempt to associate device(s)
deviceManager.associate(
request,
object : CompanionDeviceManager.Callback() {
override fun onDeviceFound(chooserLauncher: IntentSender) {
val sender = IntentSenderRequest.Builder(chooserLauncher)
.build()
bluetoothDevicePicker.launch(sender)
}
override fun onFailure(error: CharSequence?) {
//TODO: handle association failure
}
}, null
)
}

NsdManager discovers, immediately loses and re-discovers same service after WiFi is re-enabled on Android phone

In my Android app I have to show a list of available services on the network published by another machine (RPi 3B con Raspbian Stretch) using avahi 0.6.32 (Bonjour/zeroconf daemon for Linux). I obtain the list on Android phone using NsdManager.
But, during testing, I'm getting a strange behavior: when I switch WiFi off and back on in the phone, most of the times the services are discovered, then immediately lost and then rediscovered (instead of just discovered once) and all of this in less than a second.
This causes the list of services to briefly appear on screen, then disappear and finally reappear almost immediately, but it's still very noticeable. And it forces the services to be discovered and resolved twice. As I expect to have lots of phones connecting to several services in the same LAN, I want to avoid overloading the network.
I'm not sure if I'm doing something wrong or it's just the way NsdManager works on Android. To reduce possible sources of problem, I commented out the lines that resolve the services (leaving only the log messages) but the problem persisted (more then half of the times).
How can I solve it?
Sample extract from Logcat:
2019-09-26 04:33:50.262 27300-27420/com.example.myapp D/NsdHelper$initializeDiscoveryListener: Service discovery success: name: MyService-1490247, type: _mytype._tcp., host: null, port: 0, txtRecord:
2019-09-26 04:33:50.879 27300-27420/com.example.myapp D/NsdHelper$initializeDiscoveryListener: Service lost: name: MyService-1490247, type: _mytype._tcp., host: null, port: 0, txtRecord:
2019-09-26 04:33:50.970 27300-27420/com.example.myapp D/NsdHelper$initializeDiscoveryListener: Service discovery success: name: MyService-1490247, type: _mytype._tcp., host: null, port: 0, txtRecord:
I'm testing on a Samsung Note 8 with Android O. I tried with 2 different WiFi routers and the behavior is the same.
I'm using the following NsdHelper class (in Kotlin):
import android.content.Context
import android.net.nsd.NsdManager
import android.net.nsd.NsdServiceInfo
import timber.log.Timber
import java.util.*
import java.util.concurrent.ConcurrentLinkedQueue
import java.util.concurrent.atomic.AtomicBoolean
import kotlin.collections.ArrayList
abstract class NsdHelper(val context: Context) {
// Declare DNS-SD related variables for service discovery
val nsdManager: NsdManager? = context.getSystemService(Context.NSD_SERVICE) as NsdManager?
private var discoveryListener: NsdManager.DiscoveryListener? = null
private var resolveListener: NsdManager.ResolveListener? = null
private var resolveListenerBusy = AtomicBoolean(false)
private var pendingNsdServices = ConcurrentLinkedQueue<NsdServiceInfo>()
var resolvedNsdServices: MutableList<NsdServiceInfo> =
Collections.synchronizedList(ArrayList<NsdServiceInfo>())
companion object {
// Type of services to look for
const val NSD_SERVICE_TYPE: String = "_mytype._tcp."
// Services' Names must start with this
const val NSD_SERVICE_NAME: String = "MyService-"
}
// Initialize Listeners
fun initializeNsd() {
// Initialize only resolve listener
initializeResolveListener()
}
// Instantiate DNS-SD discovery listener
// used to discover available Sonata audio servers on the same network
private fun initializeDiscoveryListener() {
Timber.d("Initialize DiscoveryListener")
// Instantiate a new DiscoveryListener
discoveryListener = object : NsdManager.DiscoveryListener {
override fun onDiscoveryStarted(regType: String) {
// Called as soon as service discovery begins.
Timber.d("Service discovery started: $regType")
}
override fun onServiceFound(service: NsdServiceInfo) {
// A service was found! Do something with it
Timber.d("Service discovery success: $service")
if ( service.serviceType == NSD_SERVICE_TYPE &&
service.serviceName.startsWith(NSD_SERVICE_NAME) ) {
// Both service type and service name are the ones we want
// If the resolver is free, resolve the service to get all the details
if (resolveListenerBusy.compareAndSet(false, true)) {
nsdManager?.resolveService(service, resolveListener)
} else {
// Resolver was busy. Add the service to the list of pending services
pendingNsdServices.add(service)
}
} else {
// Not our service. Log message but do nothing else
Timber.d("Not our Service - Name: ${service.serviceName}, Type: ${service.serviceType}")
}
}
override fun onServiceLost(service: NsdServiceInfo) {
Timber.d("Service lost: $service")
// If the lost service was in the queue of pending services, remove it
synchronized(pendingNsdServices) {
val iterator = pendingNsdServices.iterator()
while (iterator.hasNext()) {
if (iterator.next().serviceName == service.serviceName) iterator.remove()
}
}
// If the lost service was in the list of resolved services, remove it
synchronized(resolvedNsdServices) {
val iterator = resolvedNsdServices.iterator()
while (iterator.hasNext()) {
if (iterator.next().serviceName == service.serviceName) iterator.remove()
}
}
// Do the rest of the processing for the lost service
onNsdServiceLost(service)
}
override fun onDiscoveryStopped(serviceType: String) {
Timber.d("Discovery stopped: $serviceType")
}
override fun onStartDiscoveryFailed(serviceType: String, errorCode: Int) {
Timber.e("Start Discovery failed: Error code: $errorCode")
stopDiscovery()
}
override fun onStopDiscoveryFailed(serviceType: String, errorCode: Int) {
Timber.e("Stop Discovery failed: Error code: $errorCode")
nsdManager?.stopServiceDiscovery(this)
}
}
}
// Instantiate DNS-SD resolve listener to get extra information about the service
private fun initializeResolveListener() {
Timber.d("Initialize ResolveListener")
resolveListener = object : NsdManager.ResolveListener {
override fun onServiceResolved(service: NsdServiceInfo) {
Timber.d("Service Resolve Succeeded: $service")
// Register the newly resolved service into our list of resolved services
resolvedNsdServices.add(service)
// Process the newly resolved service
onNsdServiceResolved(service)
// Process the next service waiting to be resolved
resolveNextInQueue()
}
override fun onResolveFailed(serviceInfo: NsdServiceInfo, errorCode: Int) {
// Called when the resolve fails. Use the error code to debug.
Timber.e("Resolve failed: $serviceInfo - Error code: $errorCode")
// Process the next service waiting to be resolved
resolveNextInQueue()
}
}
}
// Start discovering services on the network
fun discoverServices() {
// Cancel any existing discovery request
stopDiscovery()
initializeDiscoveryListener()
// Start looking for available audio channels in the network
nsdManager?.discoverServices(NSD_SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, discoveryListener)
}
// Stop DNS-SD service discovery
fun stopDiscovery() {
if (discoveryListener != null) {
Timber.d("stopDiscovery() called")
try {
nsdManager?.stopServiceDiscovery(discoveryListener)
} finally {
}
discoveryListener = null
}
}
// Resolve next NSD service pending resolution
private fun resolveNextInQueue() {
// Get the next NSD service waiting to be resolved from the queue
val nextNsdService = pendingNsdServices.poll()
if (nextNsdService != null) {
// There was one. Send to be resolved.
nsdManager?.resolveService(nextNsdService, resolveListener)
} else {
// There was no pending service. Release the flag
resolveListenerBusy.set(false)
}
}
// Function to be overriden with custom logic for new service resolved
abstract fun onNsdServiceResolved(service: NsdServiceInfo)
// Function to be overriden with custom logic for service lost
abstract fun onNsdServiceLost(service: NsdServiceInfo)
}
On the init block of the View Model, I start the service discovery:
class MyViewModel(application: Application) : AndroidViewModel(application) {
// Get application context
private val myAppContext: Context = getApplication<Application>().applicationContext
// Declare NsdHelper object for service discovery
private val nsdHelper: NsdHelper? = object : NsdHelper(myAppContext) {
override fun onNsdServiceResolved(service: NsdServiceInfo) {
// A new network service is available
// Update list of available services
updateServicesList()
}
override fun onNsdServiceLost(service: NsdServiceInfo) {
// A network service is no longer available
// Update list of available services
updateServicesList()
}
}
// Block that is run when the view model is created
init {
Timber.d("init block called")
// Initialize DNS-SD service discovery
nsdHelper?.initializeNsd()
// Start looking for available audio channels in the network
nsdHelper?.discoverServices()
}
// Called when the view model is destroyed
override fun onCleared() {
Timber.d("onCleared called")
nsdHelper?.stopDiscovery()
super.onCleared()
}
private fun updateServicesList() {
// Put the logic here to show the services on screen
return
}
}
Note: Timber is a logging utility, almost a direct replacement for standard Log commands, but easier to use.

Detect barcode scanning event from android-based mobile barcode scanner

There is a device with embedded laser barcode scanner and hardware SCAN button on Android 4.4.2. Is there any method to hook qr scan event with java interface?
Device is Sunlux xl-8681d but it detects as x301 in adb device list.

I have worked with similar device. When you click on some area where you can edit text, and scan a bar code, will it print it on the field? If yes, then you can use the following snippet inside your Activity:
Override dispatchKeyEvent method. Small sample:
#Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getCharacters() != null && !event.getCharacters().isEmpty())
//Add more code...
return super.dispatchKeyEvent(event);
}

You can do it even without EditText. You need to subscribe for broadcast intent like this:
const val QR_ACTION: String = "android.intent.ACTION_DECODE_DATA"
const val QR_EXTRA: String = "barcode_string"
private val receiver = object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
try {
Timber.d("Get intent ${intent.action}")
if (QR_ACTION == intent.action) {
if (intent.hasExtra(QR_EXTRA)) {
val code = intent.getStringExtra(QR_EXTRA)
Timber.d("New QR code $code")
// now you have qr code here
}
} }
} catch (t: Throwable) {
// handle errors
}
}
}
Please check QR_ACTION and QR_EXTRA first in to your scanner settings it can be different for different brands.

How to direct users for enabling accessibility service for my app

I know It's impossible to enable the Accessibility service for apps programmatically, so I'd like to direct users to this screen:
System settings --> Accessibility --> app name --> enable/disable screen.
Is that possible ?

You can get them to the Accessibility screen on most devices using ACTION_ACCESSIBILITY_SETTINGS. However:
that may not work on all devices, so you will want to just send them to Settings as a fallback, if you get an ActivityNotFoundException
there is no way to get them straight to any given app, let alone the enable/disable screen

You can at least make it reach the app, making the app item blink. It should work for most devices, or at least those that are like of Pixel devices:
fun <T : AccessibilityService> getRequestAccessibilityPermissionIntents(context: Context, accessibilityService: Class<T>): Array<Intent> {
var intent = Intent("com.samsung.accessibility.installed_service")
if (intent.resolveActivity(context.packageManager) == null) {
intent = Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS)
}
val extraFragmentArgKey = ":settings:fragment_args_key"
val extraShowFragmentArguments = ":settings:show_fragment_args"
val bundle = Bundle()
val showArgs = "${context.packageName}/${accessibilityService.canonicalName!!}"
bundle.putString(extraFragmentArgKey, showArgs)
intent.putExtra(extraFragmentArgKey, showArgs)
intent.putExtra(extraShowFragmentArguments, bundle)
return arrayOf(intent, Intent(Settings.ACTION_ACCESSIBILITY_SETTINGS)
.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY))
}
Usage:
private fun requestAccessibilityPermission() {
getRequestAccessibilityPermissionIntents(this, MyAccessibilityService::class.java).forEach { intent ->
try {
startActivity(intent)
return
} catch (e: Exception) {
}
}
//TODO do something here in case it failed
}