使用基于广告服务 UUID 的扫描过滤器扫描 BLE 外围设备
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【中文标题】使用基于广告服务 UUID 的扫描过滤器扫描 BLE 外围设备【英文标题】：Scanning for BLE peripherals with a scan filter based on advertised service UUID 【发布时间】：2019-11-06 13:50:04 【问题描述】：我有一个自定义的 BLE 外围设备，它可以像这样发布数据：
换句话说，我的 BLE 外围设备在广告服务数据中广告与唯一标识符关联的服务 UUID，但它不会将该服务 UUID 添加到广告服务列表中，因为如果我这样做，我在BLE 框架可在我需要时添加电池电量。
在 ios 上，我可以使用基于服务 UUID 的过滤器进行扫描并查看我的外围设备。但在 android 上，使用以下扫描过滤器，我看不到我的外围设备：
val scanSettingsBuilder = ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.setReportDelay(0L)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
scanSettingsBuilder
.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
.setMatchMode(ScanSettings.MATCH_MODE_AGGRESSIVE)
.setNumOfMatches(ScanSettings.MATCH_NUM_ONE_ADVERTISEMENT)
bluetoothAdapter?.bluetoothLeScanner?.startScan(
arrayListOf(ScanFilter.Builder().setServiceUuid(ParcelUuid(UUID.fromString("00004865-726f-6e54-7261-636b2d475053"))).build()),
scanSettingsBuilder.build(),
leScanCallback
)
谁有更多关于基于 serviceUUID 的扫描过滤器如何工作的详细信息，以及外围设备必须满足哪些条件才能被过滤器接受？
【问题讨论】：
如果您没有对扫描应用过滤器并读取所有设备，您是否能够通过检查他们的服务事后检测到您感兴趣的设备？ （并不是说这是唯一的解决方案；只是好奇。）这会导致您的 BLE 使用被标记为未优化，但如果这对您来说不是问题，这可能是一个可行的解决方案。 是的，如果我删除扫描过滤器，我可以看到我的设备并读取广告数据，但正如您指出的那样，此扫描被标记为未优化，我需要能够连续扫描也在后台，所以我想我需要扫描过滤器才能消除 Android 对后台扫描的一些限制。 好的！我正在跟踪方法调用，看看是否能找到更多关于过滤是如何实现的...... 嗯，我被困在androidxref.com/9.0.0_r3/xref/system/bt/binder/android/…；不知道如何找到生成的存根的实现。 您的 scanSettings 是什么样的？你也可以提供吗？ 【参考方案1】：我想出了如何让它工作......有点。问题是我的过滤器在serviceUuid 上，我假设它查看的是在advertisedServices 集合中宣传UUID 的外围设备。我的外设只将 UUID 作为其serviceData 关联数组中的键进行宣传，所以我切换到serviceData 过滤器如下，现在我可以找到我的外设：
AsyncTask.execute
val scanFilters = Settings.scannedBleServices.values.map
ScanFilter.Builder().setServiceData(it, null).build()
val scanSettingsBuilder = ScanSettings.Builder()
.setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
.setReportDelay(0L)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
scanSettingsBuilder
.setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
.setMatchMode(ScanSettings.MATCH_MODE_AGGRESSIVE)
.setNumOfMatches(ScanSettings.MATCH_NUM_ONE_ADVERTISEMENT)
bluetoothAdapter?.bluetoothLeScanner?.startScan(
scanFilters,
scanSettingsBuilder.build(),
leScanCallback
)
问题是现在过滤器过于宽松，因为我得到了周围每个外围设备的回调，即使是那些没有任何serviceData 的外围设备，就像我根本没有指定过滤器一样。也许是因为我在过滤器中将null 作为第二个参数传递给setServiceData，因为我不知道还要在那里添加什么。 documentation 也不是很有帮助。
我的猜测是扫描在后台工作就足够了（我还没有尝试过），但如果我可以限制回调被调用的次数并且我没有自己过滤。
【讨论】：
【参考方案2】：步骤 1)
let kServiceUART = CBUUID(string: "0x1800")
var peripheralHeartRateMonitor: CBPeripheral?`
第二步）
cbManger = CBCentralManager(delegate: self, queue: .main)
步骤 3)
extension GuidedStartOnPhoneVC: CBCentralManagerDelegate, CBPeripheralDelegate
func centralManagerDidUpdateState(_ central: CBCentralManager)
switch central.state
case .unsupported:
print("BLe Unsupported")
break
case .unauthorized:
print("BLe unauthorized")
break
case .poweredOff:
let alertMessgesInst = AlertMessages.sharedInstance
CommonUtils.showAlert(alertMessgesInst.actofit_Title, message: alertMessgesInst.trun_On_blueTooth)
break
case .poweredOn:
if isNewFirmWareOFImpulse
let uuidString = StorageServices.readFromDefaults(key: Constants.userDefaultKeys.impulseUUID)
let uuid = UUID(uuidString:uuidString as! String )
let device = cbManger.retrievePeripherals(withIdentifiers: [uuid!])
peripheralHeartRateMonitor = device.first
peripheralHeartRateMonitor!.delegate = self
cbManger?.connect(peripheralHeartRateMonitor!)
else
let option:[String: Any] = [CBCentralManagerScanOptionAllowDuplicatesKey: NSNumber(value: false)]
cbManger.scanForPeripherals(withServices: nil, options: option)
break
case .unknown:
print("BLe unknown")
break
default:
break
// End Swith
// End 'centralManagerDidUpdateState' function.
func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber)
if isNewFirmWareOFImpulse
peripheralHeartRateMonitor = peripheral
print("UUid of band is :- \(peripheralHeartRateMonitor?.identifier.uuidString)")
if impulseName == peripheral.name
peripheralHeartRateMonitor!.delegate = self
cbManger.stopScan()
// STEP 6: connect to the discovered peripheral of interest
cbManger?.connect(peripheralHeartRateMonitor!)
// End impulse condition
else
let keysArray = advertisementData.keys
if let tempImpulseName = peripheral.name
print(impulseName + " and " + tempImpulseName )
if impulseName == tempImpulseName
for key in keysArray
if key == "kCBAdvDataManufacturerData"
let manufactureData = advertisementData[key]
if let stringValue = manufactureData.debugDescription as? String
var heartValue: String = String()
heartValue = stringValue
heartValue.removeLast()
heartValue.removeLast()
let last = heartValue.removeLast()
let secondLast = heartValue.removeLast()
let hR = String([secondLast, last])
if let value = UInt8(hR, radix: 16)
if Int(value) > 60
hrArray.append(Int(value))
// End the value block
// end of if 'stringValue' condition
// end 'Key' if condition
// End for each loop
// End impulse condition
// End pheripheral if condition
// end version condition
// End function 'didDiscover peripheral'.
func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral)
// STEP 8: look for services of interest on peripheral
peripheralHeartRateMonitor?.discoverServices(nil)
// END func centralManager(... didConnect peripheral
func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?)
if error != nil
print("didDiscoverService Error :- \(error!)")
for service in peripheral.services!
print("Service: \(service)")
if service.uuid.uuidString == "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
print("Service: \(service)")
// STEP 9: look for characteristics of interest
// within services of interest
peripheral.discoverCharacteristics(nil, for: service)
// END func peripheral(... didDiscoverServices
func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?)
for characteristic in service.characteristics!
print(characteristic)
if characteristic.uuid.uuidString == "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
peripheral.setNotifyValue(true, for: characteristic)
if characteristic.uuid.uuidString == "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
peripheral.setNotifyValue(true, for: characteristic)
//
// END for
// END func peripheral(... didDiscoverCharacteristicsFor service
func peripheral(_ peripheral: CBPeripheral, didUpdateValueFor characteristic: CBCharacteristic, error: Error?)
// print(characteristic.value!.hexString)
if !isOnRestScreen
if let batteryLevelValue = characteristic.value
var buffer = [UInt8](batteryLevelValue)
// print(buffer)
print("Array count is \(buffer.count) :- \(buffer)")
if buffer.count == 20
buffer.removeFirst(4)
//MARK:- get Frame Array from the Impulse.
let array1 = Array(buffer.prefix(upTo: 8))
// let array2 = Array(buffer.suffix(from: 8))
makeProceedArray(tempArray: array1)
// makeProceedArray(tempArray: array2)
else
print("\(characteristic.service)")
// END if characteristic.uuid
func decodePeripheralState(peripheralState: CBPeripheralState)
switch peripheralState
case .disconnected:
print("Peripheral state: disconnected")
case .connected:
print("Peripheral state: connected")
case .connecting:
print("Peripheral state: connecting")
case .disconnecting:
print("Peripheral state: disconnecting")
// END func decodePeripheralState(peripheralState
func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: Error?)
// print("Disconnected!")
if error != nil
print("didDisconnectPeripheral Error :- \(error!)")
// STEP 16: in this use-case, start scanning
// for the same peripheral or another, as long
// as they're HRMs, to come back online
cbManger?.scanForPeripherals(withServices: [kServiceUART])
// END func centralManager(... didDisconnectPeripheral peripheral
// 结束扩展
【讨论】：
这是一个 iOS 解决方案的例子。问题是问题是关于 Android 的。以上是关于使用基于广告服务 UUID 的扫描过滤器扫描 BLE 外围设备的主要内容，如果未能解决你的问题，请参考以下文章