Ble scanning callback only get called several times then stopped

Question

I have 2 phones with Android 5.0.2, they both installed the latest Radius Beacon\'s App: Locate Beacon, meanwhile, I turned on 2 IBeacon sender, and can see

Answer 1

David - Are you sure that scan callback gets called for every non-connectable advertisement. I have a Xiaomi Redmi 3 and another Nexus 5 phone running Android 6.0. I have a BLE sensor that at every 1 minute interval sends the data. These phones appearing as central BLE device should receive and process the data from the sensor. I can see from an Over the Air (OTA) BLE capture device that it the sensor is sending data every 1 minute. However both phones seems to process data for few minutes at 1 minute interval but after that stop processing for 4 - 6 minutes and then start processing agenter code hereain. Time interval of phone processing on looks like this 1 min, 2 min, 3 min, 8min, 9min, 10min, 11 min So after processing 3 packets at 1 minute interval, either phone will stop processing for 4 -6 minutes.

Here is code that does the processing.

public class BluetoothDataReader {
    private final Context context;

    public BluetoothDataReader(Context context) {
        this.context = context;
    }

    public void startReading() {
        BluetoothAdapter btAdapter = getBluetoothAdapter();
        if (btAdapter == null) return;

        BluetoothLeScanner scanner = btAdapter.getBluetoothLeScanner();
        ScanSettings settings = new ScanSettings.Builder()
                .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
                .build();
        scanner.startScan(Collections.emptyList(), settings, new ScanRecordReader());
    }

    public void uploadScanBytes(SensorDataUploader sensorDataUploader, int count) {
        BluetoothAdapter btAdapter = getBluetoothAdapter();
        if (btAdapter == null) return;

        BluetoothLeScanner scanner = btAdapter.getBluetoothLeScanner();
        ScanSettings settings = new ScanSettings.Builder()
                .setScanMode(ScanSettings.SCAN_MODE_BALANCED)
                .setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
                .build();
 //       scanner.startScan(Arrays.asList(new ScanFilter.Builder().setDeviceAddress("26:50:26:50:26:50").build()), settings, new LimitedScanRecordReader(sensorDataUploader, count, scanner));
           scanner.startScan(Collections.emptyList(), settings, new LimitedScanRecordReader(sensorDataUploader, count, scanner));
    }

    @Nullable
    private BluetoothAdapter getBluetoothAdapter() {
        BluetoothAdapter btAdapter = BluetoothAdapter.getDefaultAdapter();
        if(btAdapter == null){
            Log.i(BluetoothDataReader.class.getName(), "No bluetooth adapter available");
            return null;
        }

        if(!btAdapter.isEnabled()){
            Log.i(BluetoothDataReader.class.getName(), "Enable bluetooth adapter");
            Intent enableBluetooth = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            context.startActivity(enableBluetooth);
        }
        return btAdapter;
    }

    private class LimitedScanRecordReader extends ScanCallback {
        private final int limit;
        private final BluetoothLeScanner scanner;


        private int scanRecordRead = 0;
        private final SensorDataUploader sensorDataUploader;

        private LimitedScanRecordReader( SensorDataUploader sensorDataUploader, int limit, BluetoothLeScanner scanner) {
            this.limit = limit;
            this.scanner = scanner;
            this.sensorDataUploader = sensorDataUploader;
        }

        @Override
        public void onScanResult(int callbackType, ScanResult result) {
//            if(scanRecordRead++ < limit) {
   //         if(result.getDevice().getAddress().equals("A0:E6:F8:01:02:03")) {
   //         if(result.getDevice().getAddress().equals("C0:97:27:2B:74:D5")) {

            if(result.getDevice().getAddress().equals("A0:E6:F8:01:02:03")) {
                long timestamp = System.currentTimeMillis() -
                        SystemClock.elapsedRealtime() +
                        result.getTimestampNanos() / 1000000;



                byte[] rawBytes = result.getScanRecord().getBytes();
                Log.i(DataTransferService.class.getName(), "Raw bytes: " + byteArrayToHex(rawBytes));
                sensorDataUploader.upload(timestamp, rawBytes);
            }
//            }else {
//                scanner.stopScan(this);
//            }
        }
        public String byteArrayToHex(byte[] a) {
            StringBuilder sb = new StringBuilder(a.length * 2);
            for(byte b: a)
                sb.append(String.format("%02x", b & 0xff));
            return sb.toString();
        }

        public void onScanFailed(int errorCode) {
            Log.i(DataTransferService.class.getName(), "Error code is:" + errorCode);
        }

        public void onBatchScanResults(java.util.List results) {
            Log.i(DataTransferService.class.getName(), "Batch scan results");
        }
    }

    private class ScanRecordReader extends ScanCallback {
        @Override
        public void onScanResult(int callbackType, ScanResult result) {
            byte []rawBytes = result.getScanRecord().getBytes();
            Log.i(DataTransferService.class.getName(), "Raw bytes: " + byteArrayToHex(rawBytes ));
//            Map serviceData = result.getScanRecord().getServiceData();
//            for(ParcelUuid uuid : serviceData.keySet()) {
//                Log.i(DataTransferService.class.getName(), uuid.toString() + ":" +  byteArrayToHex(serviceData.get(uuid)));
//            }
//            Log.i(DataTransferService.class.getName(),result.toString());
        }
        public String byteArrayToHex(byte[] a) {
            StringBuilder sb = new StringBuilder(a.length * 2);
            for(byte b: a)
                sb.append(String.format("%02x", b & 0xff));
            return sb.toString();
        }

        public void onScanFailed(int errorCode) {
            Log.i(DataTransferService.class.getName(), "Error code is:" + errorCode);
        }

        public void onBatchScanResults(java.util.List results) {
            Log.i(DataTransferService.class.getName(), "Batch scan results");
        }
    }
}