BLE 连续 RSSI 扫描，android 具有恒定的小时间间隔

Question

我正在制作一个应连续扫描低功耗蓝牙设备 RSSI 的 android 应用程序。我正在使用 Google API，我的 Android 版本是 4.3。我在智能手机上使用三星 Galaxy S3，我正在尝试扫描 tod Smart Beacon：https://www.todhq.com/。

问题是，我得到这样的系列值：

1. 从信标中快速获取 8 个 RSSI 值，每个值的距离约为 0.4 秒。
2. 然后有一个很大的停顿（5-6 秒），什么都没有发生。
3. 然后我再次从信标中获得 7-8 个 RSSI 值...
4. 又是大停顿...

等等。

我想要得到的是每个 RSSI 值之间的连续间隔。它们不必是精确的间隔，但至少是接近的。我尝试过不同的示例，但并不真正知道问题出在哪里。也许 tod 智能信标只在 5 秒之间做广告？我可以通过更新固件来改变广告的间隔。但是，它在非常短的时间间隔之间获得许多值是没有意义的，并且这些值是不同的（= 它们不是每个值的副本）。

我一直使用的代码在这里：

public class MainActivity extends ListActivity {
    ArrayList<String> listItems=new ArrayList<String>();
    ArrayAdapter<String> adapter;

    private static final String TAG=MainActivity.class.getSimpleName();
    private BluetoothAdapter mBluetoothAdapter;
    private boolean mScanning;
    private Handler mHandler = new Handler();
    private int scanCount;
    private static final int REQUEST_ENABLE_BT=123456;

    // Stops scanning after 1000 seconds.
    private static final long SCAN_PERIOD = 1000000;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            adapter=new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,listItems);
            setListAdapter(adapter);

            checkBLE();
            init();
            boolean ret = enableBLE();
            if(ret){
                    startScan(false);
            }else{
                    Log.d(TAG,getCtx()+" onCreate Waiting for on onActivityResult");
            }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.main, menu);
            return true;
    }

    private void init(){
            // Initializes Bluetooth adapter.
            final BluetoothManager bluetoothManager =
                            (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
            mBluetoothAdapter = bluetoothManager.getAdapter();
    }
    private void startScan(boolean success){
            if(mBluetoothAdapter == null){
                    init();
            }
            if(success){
                    mScanning=true;
                    scanLeDevice(mScanning);
                    return;
            }
            if(enableBLE()){
                    mScanning=true;
                    scanLeDevice(mScanning);
            }else{
                    Log.d(TAG,getCtx()+" startScan Waiting for on onActivityResult success:"+success);
            }
    }
    private void scanLeDevice(final boolean enable) {
            if (enable) {
                    // Stops scanning after a pre-defined scan period.
                    mHandler.postDelayed(new Runnable() {
                            @Override
                            public void run() {
                                    mScanning = false;
                                    Log.d(TAG,getCtx() + "run stopLeScan");
                                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
                            }
                    }, SCAN_PERIOD);
                    Log.d(TAG,getCtx()+" scanLeDevice startLeScan:"+enable);
                    mBluetoothAdapter.startLeScan(mLeScanCallback);
            } else {
                    Log.d(TAG,getCtx()+ " scanLeDevice stopLeScan:"+enable);
                    mBluetoothAdapter.stopLeScan(mLeScanCallback);
            }
    }
    private static String getCtx(){
            Date dt = new Date();
            return dt+ " thread:"+Thread.currentThread().getName();
    }
    // Device scan callback.
    private BluetoothAdapter.LeScanCallback mLeScanCallback =
                    new BluetoothAdapter.LeScanCallback() {
            @Override
            public void onLeScan(final BluetoothDevice device, final int rssi,
                            final byte[] scanRecord) {
                    runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                    scanCount++;

                                    String msg=getCtx()+
                                                    "\nLeScanCallback.onLeScan stopLeScan run " +scanCount+
                                                    "\nDevice:" +device+
                                                    "\nRssi:" + rssi+
                                                    "\nScanRecord:";
                                    Log.d(TAG,msg);
                                    addItems(msg);
                            }
                    });
            }
    };
    private void addItems(String msg) {
            synchronized(listItems){
                    listItems.add(msg);
                    adapter.notifyDataSetChanged();
            }
    }
    public void startScan(View v) {
            startScan(false);
    }
    public void stopScan(View v) {
            mScanning=false;
            scanLeDevice(mScanning);
    }
    public void clear(View v) {
            Log.d(TAG,getCtx()+" called clear");
            synchronized(listItems){
                    listItems.clear();
                    adapter.notifyDataSetChanged();
            }
    }
    private  void checkBLE(){
            // Use this check to determine whether BLE is supported on the device. Then
            // you can selectively disable BLE-related features.
            if (!getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE)) {
                    Toast.makeText(this, R.string.ble_not_supported, Toast.LENGTH_SHORT).show();
                    finish();
            }
    }
    private boolean enableBLE(){
            boolean ret=true;
            // Ensures Bluetooth is available on the device and it is enabled. If not,
            // displays a dialog requesting user permission to enable Bluetooth.
            if (mBluetoothAdapter == null || !mBluetoothAdapter.isEnabled()) {
                    Log.d(TAG,getCtx()+" enableBLE either mBluetoothAdapter == null or disabled:"+mBluetoothAdapter);
                    Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
                    startActivityForResult(enableBtIntent,REQUEST_ENABLE_BT);
                    ret=false;
            }
            return ret;
    }
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            Log.d(TAG,getCtx()+" onActivityResult requestCode="+requestCode+
                            ", resultCode="+resultCode+", Intent:"+data
                            );
            if(requestCode == REQUEST_ENABLE_BT && resultCode == RESULT_OK){
                    startScan(true);
            }
    }

}

Answer 1

有一种叫做“蓝牙嗅探器”的设备，你可以用它来检查信标是否按照你的预期发送信号。