蓝牙 LE - 如何设置自定义扫描延迟？

Question

I am making an app to scan all tags using Bluetooth LE. I have to implement a interval feature where an user can enter seconds for scan delay, but i have not found any method to do so. I tried implementing TimerTask but it still scans more than one device in a second Is there any way to implement a interval such as scanning one tag every second or more?

My code:

class BluetoothActivity : AppCompatActivity(), MenuProvider{
    
        private lateinit var recyclerView: RecyclerView
        private var bluetoothLeScanner: BluetoothLeScanner? = null
        private val deviceList = mutableListOf<BleTag>()
        private val deviceMap = mutableMapOf<String, BleTag>()
        private var interval: Long = 0
        private lateinit var menu: Menu
        private lateinit var tagBinding: ListbluethoothBinding
        val before = DateFormat.getDateTimeInstance().format(Date(System.currentTimeMillis()))
    
        private val scanCallback = object : ScanCallback(){
            @RequiresApi(Build.VERSION_CODES.N)
            @SuppressLint("MissingPermission", "NotifyDataSetChanged")
    
            override fun onScanResult(callbackType: Int, result: ScanResult) {
    
               val scanJob = CoroutineScope(Dispatchers.Main).launch {
                    val tag = deviceMap.computeIfAbsent(result.device.address) {
                        val newTag = BleTag(result.device.name ?: "Unbekannt", result.device.address, result.rssi , result.scanRecord?.bytes, "")
                        deviceList.add(newTag)
                        newTag
                    }
                    tag.name = result.device.name ?: "Unbekannt"
                    tag.rssi = result.rssi
                    tag.advertisementData = result.scanRecord?.bytes
                }
    
                deviceList.sortBy {result.rssi }
    
                menu.findItem(R.id.count).title = "Geräte: " + deviceList.size
    
                super.onScanResult(callbackType, result)
            }
    
            override fun onScanFailed(errorCode: Int) {
                super.onScanFailed(errorCode)
                Log.e("Scan failed","")
            }
        }
    
    
    
        @SuppressLint("MissingPermission")
        @RequiresApi(Build.VERSION_CODES.M)
        override fun onCreate(savedInstanceState: Bundle?) {
    
            super.onCreate(savedInstanceState)
    
            tagBinding = ListbluethoothBinding.inflate(layoutInflater)
            val view = tagBinding.root
            setContentView(view)
    
            recyclerView = tagBinding.list
    
            val layoutManager = LinearLayoutManager(this)
            recyclerView.layoutManager = layoutManager
            recyclerView.adapter = RecyclerViewAdapter(deviceList)
    
            addMenuProvider(this)
    
            val bluetoothManager: BluetoothManager = getSystemService(BluetoothManager::class.java)
            val bluetoothAdapter: BluetoothAdapter? = bluetoothManager.adapter
            bluetoothLeScanner = bluetoothAdapter?.bluetoothLeScanner
    
            interval = getSharedPreferences("interval", MODE_PRIVATE).getLong("interval", 1000)
    
            bluetoothLeScanner!!.startScan(scanCallback)
    
        }
    
    
        override fun onCreateMenu(menu: Menu, menuInflater: MenuInflater) {
            MainActivity@this.menu = menu
            menuInflater.inflate(R.menu.items, menu)
        }
    
        @RequiresApi(Build.VERSION_CODES.M)
        @SuppressLint("MissingPermission")
        override fun onMenuItemSelected(menuItem: MenuItem): Boolean {
    
            when(menuItem.itemId) {
    
                R.id.stop -> {
                    bluetoothLeScanner!!.stopScan(scanCallback)
                    Snackbar.make(findViewById(android.R.id.content),"Scan gestoppt", 2000).show()
                }
                R.id.start -> {
                    bluetoothLeScanner!!.startScan(scanCallback)
                    Snackbar.make(findViewById(android.R.id.content),"Scan gestartet", 2000).show()
                }
            }
            return true
        }
    }

Answer 1

Unfortunately Android does not give you this granularity, and the values are set in the source code as can be seen here . In terms of setting it via an API, the only thing you can do is set SCAN_MODE_LOW_LATENCY via the ScanSettings class .

Some people have found a few workarounds around this which you can find in the links below:-

• How to increase scan period for BLE Android devices
• Is it possible to reduce the time to scan BLE devices
• How to set BLE scan window and interval not just mode