CheckPermission.kt

if (!usbManager!!.hasPermission(usbDevice)) {
    usbManager!!.requestPermission(usbDevice, mPendingIntent)
}

RegisterBroadcastRecevier.kt

private val usbReceiver: BroadcastReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context, intent: Intent) {
        if (ACTION_USB_PERMISSION.equals(intent.action, ignoreCase = true)) {
            runOnUiThread {
                val device = intent.getParcelableExtra<UsbDevice>(UsbManager.EXTRA_DEVICE)
                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false) && device != null) {
                    usbDevice = device
                    if (permissionUpdater != null)
                        permissionUpdater?.onSuccess()
                } else {
                    if (permissionUpdater != null)
                        permissionUpdater?.onError()
                }
            }
        }
    }
}

UsbCommHandler.kt

fun getUsbComm(): UsbCommHandler? {
    if (usbCommHandler == null) {
        val driver = usbDevice?.let { UsbDriver(it) }
            if (driver != null) {
                val usbConnection = usbManager!!.openDevice(driver.getDevice())
                usbCommHandler = UsbCommHandler()
                usbCommHandler?.initHandler(driver, usbConnection, userPreferences, appDatabase)
                mUsbCommunication = UsbCommunication.getInstance()
                mUsbCommunication.setUsbDriver(object : IUsbDriver {
                    override fun getSerialPort(): IUsbSerialPort {
                        return object : IUsbSerialPort {
                            override fun write(src: ByteArray, timeout: Int) {
                                if (ThirdMainViewModel.stopFlag) return
                                driver.getPort()?.write(src, timeout)
                            }

                            override fun initialiseDriverConnection() {
                                if (ThirdMainViewModel.stopFlag) return
                                driver.getPort()?.let {
                                    if (!it.isOpen()) {
                                        it.open(usbConnection)
                                        it.setParameters(
                                            UsbSerialPort.BAUD_RATE,
                                            UsbSerialPort.DATA_BITS_8,
                                            UsbSerialPort.STOP_BITS_1,
                                            UsbSerialPort.PARITY_NONE
                                        )
                                        it.setDTR(true)
                                    }
                                }
                            }

                            override fun read(dest: ByteArray, timeout: Int): Int? {
                                return driver.getPort()?.read(dest, timeout)
                            }
                        }
                    }
                })
            }
    }
    return usbCommHandler
}

UsbDeviceScanner.kt

private fun setupReceiver(permissionUpdater: PermissionUpdater?) {
    this.permissionUpdater = permissionUpdater
    usbManager = getSystemService(Context.USB_SERVICE) as UsbManager
    Executors.newSingleThreadExecutor().execute {
        registerReceiver(usbReceiver, IntentFilter(ACTION_USB_PERMISSION))
        isUSBMgrRegisterd = true
    }
    val deviceList = usbManager!!.deviceList
    if (deviceList.size != 0) {
        for (device in deviceList.keys) {
            val usbDevice = deviceList[device]
            if (usbDevice?.vendorId == 10985 && usbDevice.productId == 256) {
                foundDevice = true
                if (!usbManager!!.hasPermission(usbDevice)) {
                    usbManager!!.requestPermission(usbDevice, mPendingIntent)
                } else {
                    this.usbDevice = usbDevice
                    if(permissionUpdater!=null)
                        permissionUpdater.onSuccess()
                }
            }
        }
        if (!foundDevice && deviceList.size != 0) {
            // Handle device not found scenario
        }
    } 
}