Receiving multiple BLE Packets per one connection interval in Android

Question

My device information

Nordic board :
- MTU size : 247.
- This board send notification multiple packets in one connection interval (Just counter value like 1,2,3,4...) at "Heart Rate Measurement".
Android device :
- Version 5.0 and 6.0. (Using two device).
- communicate Bluetooth Low Energy(BLE) with board.
- board connect with my Android app MTU is setting 244.
- Application source is google sample project BluetoothLeGatt
- App send notification value at "Heart Rate Service" characteristic.
- Receive notification value at Gattcallback "onCharacteristicChanged()"
Problem
- My Android app lost some packet.

I read this post. Maximizing BLE Throughput on iOS and Android. So I send E-mail this post author and I search another information for Android.

I found some similarly question. but that question answer was not work. Then I found one question what I want exactly. but this question have no answers. Android receiving multiple BLE packets per connection interval. Unfortunately I don't have any reply E-mail answer.

My question is how do I set Android BLE notification. (Not Nordic board setting) (My question is same Android receiving multiple BLE packets per connection interval)

Under line is my sample code. at notification.

@Connect

public boolean connect(final String address) {
    if (mBluetoothAdapter == null || address == null) {
        Log.w(TAG, "BluetoothAdapter not initialized or unspecified address.");
        return false;
    }

    // Previously connected device.  Try to reconnect.
    if (mBluetoothDeviceAddress != null && address.equals(mBluetoothDeviceAddress) && mBluetoothGatt != null) {
        Log.d(TAG, "Trying to use an existing mBluetoothGatt for connection.");
        if (mBluetoothGatt.connect()) {
            mConnectionState = STATE_CONNECTING;
            return true;
        } else {
            return false;
        }
    }

    final BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
    if (device == null) {
        Log.w(TAG, "Device not found.  Unable to connect.");
        return false;
    }

    // We want to directly connect to the device, so we are setting the autoConnect
    // parameter to false.
    mBluetoothGatt = device.connectGatt(this, false, mGattCallback);

    Log.d(TAG, "Trying to create a new connection.");
    mBluetoothDeviceAddress = address;
    mConnectionState = STATE_CONNECTING;
    return true;
}

@GattCallback

  /*broadcastUpdate method is display value*/
 @Override
    public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {

        if (newState == BluetoothProfile.STATE_CONNECTED) {
            mConnectionState = STATE_CONNECTED;
            // Attempts to discover services after successful connection.
            Log.i(TAG, "Attempting to start service discovery:");
            mBluetoothGatt.discoverServices();

        } else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
            Log.i(TAG, "Disconnected from GATT server.");
            mConnectionState = STATE_DISCONNECTED;
            broadcastUpdate(ACTION_GATT_DISCONNECTED);
        }
    }

    @Override
    public void onServicesDiscovered(BluetoothGatt gatt, int status) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            Log.d(TAG, "onServicesDiscovered success: (status)" + status);
            //findServiceOther(gatt);
            broadcastUpdate(ACTION_GATT_SERVICES_DISCOVERED);
            Log.d(TAG, "Request MTU");
            gatt.requestMtu(SET_MTU);
        } else {
            Log.w(TAG, "onServicesDiscovered failed: (status)" + status);
        }
    }

    @Override
    public void onCharacteristicRead(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status) {
        if (status == BluetoothGatt.GATT_SUCCESS) {
            Log.d(TAG, "onCharRead Success");
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
        } else {
            Log.d(TAG, "OnCharRead Error: " + status);
        }
    }

    @Override
    public void onCharacteristicChanged(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic) {
        if (characteristic.getUuid().equals(SampleGattAttributes.UUID_HEART_RATE_MEASUREMENT))
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic, FLAG_HEART_RATE);
        else
            broadcastUpdate(ACTION_DATA_AVAILABLE, characteristic);
    }

    @Override
    public void onMtuChanged(BluetoothGatt gatt, int mtu, int status) {
        super.onMtuChanged(gatt, mtu, status);
        boolean priority = gatt.requestConnectionPriority(BluetoothGatt.CONNECTION_PRIORITY_HIGH);
        Log.d(TAG, "MTU changed (mtu/status) / Priority : (" + mtu + "/" + status + ") / " + priority);
        changed_MTU_Size = mtu;
        broadcastUpdate(ACTION_DATA_AVAILABLE, changed_MTU_Size, FLAG_MTU);
        broadcastUpdate(ACTION_GATT_CONNECTED);
    }

@set notification

public void setCharacteristicNotification(BluetoothGattCharacteristic characteristic, boolean enabled) {
    if (mBluetoothAdapter == null || mBluetoothGatt == null) {
        Log.w(TAG, "BluetoothAdapter not initialized");
        return;
    }

    mBluetoothGatt.setCharacteristicNotification(characteristic, enabled);

    if (SampleGattAttributes.UUID_HEART_RATE_MEASUREMENT.equals(characteristic.getUuid())) {
        // This is specific to Heart Rate Measurement.
        BluetoothGattDescriptor descriptor = characteristic.getDescriptor(SampleGattAttributes.UUID_CLIENT_CHARACTERISTIC_CONFIG);
        descriptor.setValue(BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE);
        mBluetoothGatt.writeDescriptor(descriptor);
    }
}

Edit_1

I test Nordic offical app in Google play store. nRF Connect for Mobile but this app miss packet too.

Edit_2

I found some problem too.

< Nordic board constant setting>

HEART_RATE_MEAS_INTERVAL : 10
MIN_CONN_INTERVAL : MSEC_TO_UNITS(40, UNIT_1_25_MS)
MAX_CONN_INTERVAL : MSEC_TO_UNITS(40, UNIT_1_25_MS)
SLAVE_LATENCY 0
CONN_SUP_TIMEOUT MSEC_TO_UNITS(4000, UNIT_10_MS)

< Run in my Android app >

skip requestMTU : receive 20byte packet successful. (Data rate average is 2200byte/second in my app)
requestMTU : I try so many MTU size (ex: 23(can small size), 40, 100, 255(target) ...) but lost some packet (Data rate 8500 ~ 9500 byte/second in my app)

I wonder requestMTU and notification receive interrelation.

Receiving multiple BLE Packets per one connection interval in Android

Answers (1)

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