Bluetooth Low Energy (BLE) helper class for Android, including a queue for characteristic writes. See http://stackoverflow.com/questions/18011816/has-native-android-ble-gatt-implementation-synchronous-nature

Bluetooth.java

package com.nojack;

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattDescriptor;
import android.bluetooth.BluetoothGattService;
import android.bluetooth.BluetoothManager;
import android.bluetooth.BluetoothProfile;
import android.content.Context;
import android.content.pm.PackageManager;
import android.os.Handler;
import android.util.Log;

import org.bluetooth.bledemo.BleNamesResolver;
import org.bluetooth.bledemo.BleWrapperUiCallbacks;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Queue;
import java.util.UUID;

public class Bluetooth {

    /* defines (in milliseconds) how often RSSI should be updated */
    private static final int RSSI_UPDATE_TIME_INTERVAL = 1500; // 1.5 seconds

    /* callback object through which we are returning results to the caller */
    private BleWrapperUiCallbacks mUiCallback = null;
    /* define NULL object for UI callbacks */
    private static final BleWrapperUiCallbacks NULL_CALLBACK = new BleWrapperUiCallbacks.Null();

    private static Bluetooth mInstance = null;

    /* creates BleWrapper object, set its parent activity and callback object */
    private Bluetooth(Activity parent, BleWrapperUiCallbacks callback)
    {
        this.setDependencies(parent, callback);
    }

    public static Bluetooth getInstance(Activity parent, BleWrapperUiCallbacks callback)
    {
        if(mInstance == null)
        {
            mInstance = new Bluetooth(parent, callback);
        }
        else {
            mInstance.setDependencies(parent, callback);
        }
        return mInstance;
    }

    public void setDependencies(Activity parent, BleWrapperUiCallbacks callback) {

        this.mParent = parent;
        mUiCallback = callback;
        if(mUiCallback == null) mUiCallback = NULL_CALLBACK;
    }

    public BluetoothManager getManager() { return mBluetoothManager; }
    public BluetoothAdapter getAdapter() { return mBluetoothAdapter; }
    public BluetoothDevice getDevice()  { return mBluetoothDevice; }
    public BluetoothGatt getGatt()    { return mBluetoothGatt; }
    public BluetoothGattService getCachedService() { return mBluetoothSelectedService; }
    public List<BluetoothGattService> getCachedServices() { return mBluetoothGattServices; }
    public boolean                    isConnected() { return mConnected; }

    /* run test and check if this device has BT and BLE hardware available */
    public boolean checkBleHardwareAvailable() {
        // First check general Bluetooth Hardware:
        // get BluetoothManager...
        final BluetoothManager manager = (BluetoothManager) mParent.getSystemService(Context.BLUETOOTH_SERVICE);
        if(manager == null) return false;
        // .. and then get adapter from manager
        final BluetoothAdapter adapter = manager.getAdapter();
        if(adapter == null) return false;

        // and then check if BT LE is also available
        boolean hasBle = mParent.getPackageManager().hasSystemFeature(PackageManager.FEATURE_BLUETOOTH_LE);
        return hasBle;
    }

    /* before any action check if BT is turned ON and enabled for us
     * call this in onResume to be always sure that BT is ON when Your
     * application is put into the foreground */
    public boolean isBtEnabled() {
        final BluetoothManager manager = (BluetoothManager) mParent.getSystemService(Context.BLUETOOTH_SERVICE);
        if(manager == null) return false;

        final BluetoothAdapter adapter = manager.getAdapter();
        if(adapter == null) return false;

        return adapter.isEnabled();
    }

    /* start scanning for BT LE devices around */
    public void startScanning() {
        mBluetoothAdapter.startLeScan(mDeviceFoundCallback);
    }

    /* stops current scanning */
    public void stopScanning() {
        mBluetoothAdapter.stopLeScan(mDeviceFoundCallback);
    }

    /* initialize BLE and get BT Manager & Adapter */
    public boolean initialize() {
        if (mBluetoothManager == null) {
            mBluetoothManager = (BluetoothManager) mParent.getSystemService(Context.BLUETOOTH_SERVICE);
            if (mBluetoothManager == null) {
                return false;
            }
        }

        if(mBluetoothAdapter == null) mBluetoothAdapter = mBluetoothManager.getAdapter();
        if (mBluetoothAdapter == null) {
            return false;
        }
        return true;
    }

    /* connect to the device with specified address */
    public boolean connect(final String deviceAddress) {
        if (mBluetoothAdapter == null || deviceAddress == null) return false;
        mDeviceAddress = deviceAddress;

        // check if we need to connect from scratch or just reconnect to previous device
        if(mBluetoothGatt != null && mBluetoothGatt.getDevice().getAddress().equals(deviceAddress)) {
            // just reconnect
            return mBluetoothGatt.connect();
        }
        else {
            // connect from scratch
            // get BluetoothDevice object for specified address
            mBluetoothDevice = mBluetoothAdapter.getRemoteDevice(mDeviceAddress);
            if (mBluetoothDevice == null) {
                // we got wrong address - that device is not available!
                return false;
            }
            // connect with remote device
            mBluetoothGatt = mBluetoothDevice.connectGatt(mParent, false, mBleCallback);
        }
        return true;
    }

    /* disconnect the device. It is still possible to reconnect to it later with this Gatt client */
    public void disconnect() {
        if(mBluetoothGatt != null) mBluetoothGatt.disconnect();

        mUiCallback.uiDeviceDisconnected(mBluetoothGatt, mBluetoothDevice);
    }

    /* close GATT client completely */
    public void close() {
        if(mBluetoothGatt != null) mBluetoothGatt.close();
        mBluetoothGatt = null;
    }

    /* request new RSSi value for the connection*/
    public void readPeriodicalyRssiValue(final boolean repeat) {
        mTimerEnabled = repeat;
        // check if we should stop checking RSSI value
        if(mConnected == false || mBluetoothGatt == null || mTimerEnabled == false) {
            mTimerEnabled = false;
            return;
        }

        mTimerHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                if(mBluetoothGatt == null ||
                        mBluetoothAdapter == null ||
                        mConnected == false)
                {
                    mTimerEnabled = false;
                    return;
                }

                // request RSSI value
                mBluetoothGatt.readRemoteRssi();
                // add call it once more in the future
                readPeriodicalyRssiValue(mTimerEnabled);
            }
        }, RSSI_UPDATE_TIME_INTERVAL);
    }

    /* starts monitoring RSSI value */
    public void startMonitoringRssiValue() {
        readPeriodicalyRssiValue(true);
    }

    /* stops monitoring of RSSI value */
    public void stopMonitoringRssiValue() {
        readPeriodicalyRssiValue(false);
    }

    /* request to discover all services available on the remote devices
     * results are delivered through callback object */
    public void startServicesDiscovery() {
        if(mBluetoothGatt != null) mBluetoothGatt.discoverServices();
    }

    /* gets services and calls UI callback to handle them
     * before calling getServices() make sure service discovery is finished! */
    public void getSupportedServices() {
        if(mBluetoothGattServices != null && mBluetoothGattServices.size() > 0) mBluetoothGattServices.clear();
        // keep reference to all services in local array:
        if(mBluetoothGatt != null) mBluetoothGattServices = mBluetoothGatt.getServices();

        mUiCallback.uiAvailableServices(mBluetoothGatt, mBluetoothDevice, mBluetoothGattServices);
    }

    /* get all characteristic for particular service and pass them to the UI callback */
    public void getCharacteristicsForService(final BluetoothGattService service) {
        if(service == null) return;
        List<BluetoothGattCharacteristic> chars = null;

        chars = service.getCharacteristics();
        mUiCallback.uiCharacteristicForService(mBluetoothGatt, mBluetoothDevice, service, chars);
        // keep reference to the last selected service
        mBluetoothSelectedService = service;
    }

    /* request to fetch newest value stored on the remote device for particular characteristic */
    public void requestCharacteristicValue(BluetoothGattCharacteristic ch) {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) return;

        mBluetoothGatt.readCharacteristic(ch);
        // new value available will be notified in Callback Object
    }

    /* get characteristic's value (and parse it for some types of characteristics)
     * before calling this You should always update the value by calling requestCharacteristicValue() */
    public void getCharacteristicValue(BluetoothGattCharacteristic ch) {
        /*
        if (mBluetoothAdapter == null || mBluetoothGatt == null || ch == null) return;

        byte[] rawValue = ch.getValue();
        String strValue = null;
        int intValue = 0;

        // lets read and do real parsing of some characteristic to get meaningful value from it
        UUID uuid = ch.getUuid();

        if(uuid.equals(BleDefinedUUIDs.Characteristic.HEART_RATE_MEASUREMENT)) { // heart rate
        	// follow https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.heart_rate_measurement.xml
        	// first check format used by the device - it is specified in bit 0 and tells us if we should ask for index 1 (and uint8) or index 2 (and uint16)
        	int index = ((rawValue[0] & 0x01) == 1) ? 2 : 1;
        	// also we need to define format
        	int format = (index == 1) ? BluetoothGattCharacteristic.FORMAT_UINT8 : BluetoothGattCharacteristic.FORMAT_UINT16;
        	// now we have everything, get the value
        	intValue = ch.getIntValue(format, index);
        	strValue = intValue + " bpm"; // it is always in bpm units
        }
        else if (uuid.equals(BleDefinedUUIDs.Characteristic.HEART_RATE_MEASUREMENT) || // manufacturer name string
        		 uuid.equals(BleDefinedUUIDs.Characteristic.MODEL_NUMBER_STRING) || // model number string)
        		 uuid.equals(BleDefinedUUIDs.Characteristic.FIRMWARE_REVISION_STRING)) // firmware revision string
        {
        	// follow https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.manufacturer_name_string.xml etc.
        	// string value are usually simple utf8s string at index 0
        	strValue = ch.getStringValue(0);
        }
        else if(uuid.equals(BleDefinedUUIDs.Characteristic.APPEARANCE)) { // appearance
        	// follow: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.gap.appearance.xml
        	intValue  = ((int)rawValue[1]) << 8;
        	intValue += rawValue[0];
        	strValue = BleNamesResolver.resolveAppearance(intValue);
        }
        else if(uuid.equals(BleDefinedUUIDs.Characteristic.BODY_SENSOR_LOCATION)) { // body sensor location
        	// follow: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.body_sensor_location.xml
        	intValue = rawValue[0];
        	strValue = BleNamesResolver.resolveHeartRateSensorLocation(intValue);
        }
        else if(uuid.equals(BleDefinedUUIDs.Characteristic.BATTERY_LEVEL)) { // battery level
        	// follow: https://developer.bluetooth.org/gatt/characteristics/Pages/CharacteristicViewer.aspx?u=org.bluetooth.characteristic.battery_level.xml
        	intValue = rawValue[0];
        	strValue = "" + intValue + "% battery level";
        }
        else {
        	// not known type of characteristic, so we need to handle this in "general" way
        	// get first four bytes and transform it to integer
        	intValue = 0;
        	if(rawValue.length > 0) intValue = (int)rawValue[0];
        	if(rawValue.length > 1) intValue = intValue + ((int)rawValue[1] << 8);
        	if(rawValue.length > 2) intValue = intValue + ((int)rawValue[2] << 8);
        	if(rawValue.length > 3) intValue = intValue + ((int)rawValue[3] << 8);

            if (rawValue.length > 0) {
                final StringBuilder stringBuilder = new StringBuilder(rawValue.length);
                for(byte byteChar : rawValue) {
                    stringBuilder.append(String.format("%c", byteChar));
                }
                strValue = stringBuilder.toString();
            }
        }
        */
        String timestamp = new SimpleDateFormat("yyyy.MM.dd HH:mm:ss.SSS").format(new Date());
        mUiCallback.uiNewValueForCharacteristic(mBluetoothGatt,
                mBluetoothDevice,
                mBluetoothSelectedService,
                ch,
                null,
                0,
                null,
                timestamp);
    }

    /* reads and return what what FORMAT is indicated by characteristic's properties
     * seems that value makes no sense in most cases */
    public int getValueFormat(BluetoothGattCharacteristic ch) {
        int properties = ch.getProperties();

        if((BluetoothGattCharacteristic.FORMAT_FLOAT & properties) != 0) return BluetoothGattCharacteristic.FORMAT_FLOAT;
        if((BluetoothGattCharacteristic.FORMAT_SFLOAT & properties) != 0) return BluetoothGattCharacteristic.FORMAT_SFLOAT;
        if((BluetoothGattCharacteristic.FORMAT_SINT16 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_SINT16;
        if((BluetoothGattCharacteristic.FORMAT_SINT32 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_SINT32;
        if((BluetoothGattCharacteristic.FORMAT_SINT8 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_SINT8;
        if((BluetoothGattCharacteristic.FORMAT_UINT16 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_UINT16;
        if((BluetoothGattCharacteristic.FORMAT_UINT32 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_UINT32;
        if((BluetoothGattCharacteristic.FORMAT_UINT8 & properties) != 0) return BluetoothGattCharacteristic.FORMAT_UINT8;

        return 0;
    }

    /* set new value for particular characteristic */
    public void writeDataToCharacteristic(final BluetoothGattCharacteristic ch, final byte[] dataToWrite)
    {
        if (mBluetoothAdapter == null || mBluetoothGatt == null || ch == null) return;

        // first set it locally....
        ch.setValue(dataToWrite);
        // ... and then "commit" changes to the peripheral
        mBluetoothGatt.writeCharacteristic(ch);
    }

    /* enables/disables notification for characteristic */
    public void setNotificationForCharacteristic(BluetoothGattCharacteristic ch, boolean enabled)
    {
        if (mBluetoothAdapter == null || mBluetoothGatt == null) return;

        boolean success = mBluetoothGatt.setCharacteristicNotification(ch, enabled);
        if(!success) {
            Log.e("------", "Seting proper notification status for characteristic failed!");
        }

        // This is also sometimes required (e.g. for heart rate monitors) to enable notifications/indications
        // see: https://developer.bluetooth.org/gatt/descriptors/Pages/DescriptorViewer.aspx?u=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
        BluetoothGattDescriptor descriptor = ch.getDescriptor(UUID.fromString("00002902-0000-1000-8000-00805f9b34fb"));
        if(descriptor != null) {
            byte[] val = enabled ? BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE : BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE;
            descriptor.setValue(val);
            mBluetoothGatt.writeDescriptor(descriptor);
        }
    }

    /* defines callback for scanning results */
    private BluetoothAdapter.LeScanCallback mDeviceFoundCallback = new BluetoothAdapter.LeScanCallback() {
        @Override
        public void onLeScan(final BluetoothDevice device, final int rssi, final byte[] scanRecord) {
            mUiCallback.uiDeviceFound(device, rssi, scanRecord);
        }
    };

    /* callbacks called for any action on particular Ble Device */
    private final BluetoothGattCallback mBleCallback = new BluetoothGattCallback() {
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState) {
            if (newState == BluetoothProfile.STATE_CONNECTED) {
                mConnected = true;
                mUiCallback.uiDeviceConnected(mBluetoothGatt, mBluetoothDevice);

                // now we can start talking with the device, e.g.
                mBluetoothGatt.readRemoteRssi();
                // response will be delivered to callback object!

                // in our case we would also like automatically to call for services discovery
                startServicesDiscovery();

                // and we also want to get RSSI value to be updated periodically
                startMonitoringRssiValue();
            }
            else if (newState == BluetoothProfile.STATE_DISCONNECTED) {
                mConnected = false;
                mUiCallback.uiDeviceDisconnected(mBluetoothGatt, mBluetoothDevice);
            }
        }

        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status) {
            if (status == BluetoothGatt.GATT_SUCCESS) {
                // now, when services discovery is finished, we can call getServices() for Gatt
                getSupportedServices();
            }
        }

        @Override
        public void onReadRemoteRssi(BluetoothGatt gatt, int rssi, int status) {
            if(status == BluetoothGatt.GATT_SUCCESS) {
                // we got new value of RSSI of the connection, pass it to the UI
                mUiCallback.uiNewRssiAvailable(mBluetoothGatt, mBluetoothDevice, rssi);
            }
        };

        @Override
        public void onCharacteristicChanged(BluetoothGatt gatt,
                                            BluetoothGattCharacteristic characteristic)
        {
            // characteristic's value was updated due to enabled notification, lets get this value
            // the value itself will be reported to the UI inside getCharacteristicValue
            getCharacteristicValue(characteristic);
            // also, notify UI that notification are enabled for particular characteristic
            mUiCallback.uiGotNotification(mBluetoothGatt, mBluetoothDevice, mBluetoothSelectedService, characteristic);
        }

        // we got response regarding our request to fetch characteristic value
        @Override
        public void onCharacteristicRead(BluetoothGatt gatt,
                                         BluetoothGattCharacteristic characteristic,
                                         int status)
        {
            // Ready for next transmission
            processTxQueue();

            if (status == BluetoothGatt.GATT_SUCCESS) {
                // Succeeded, so we can get the value
                getCharacteristicValue(characteristic);
            }
        }

        @Override
        public void onCharacteristicWrite(BluetoothGatt gatt, BluetoothGattCharacteristic characteristic, int status)
        {
            String deviceName = gatt.getDevice().getName();
            String serviceName = BleNamesResolver.resolveServiceName(characteristic.getService().getUuid().toString().toLowerCase(Locale.getDefault()));
            String charName = BleNamesResolver.resolveCharacteristicName(characteristic.getUuid().toString().toLowerCase(Locale.getDefault()));
            String description = "Device: " + deviceName + " Service: " + serviceName + " Characteristic: " + charName;

            // Ready for next transmission
            processTxQueue();

            // we got response regarding our request to write new value to the characteristic
            // let see if it failed or not
            if(status == BluetoothGatt.GATT_SUCCESS) {
                mUiCallback.uiSuccessfulWrite(mBluetoothGatt, mBluetoothDevice, mBluetoothSelectedService, characteristic, description);
            }
            else {
                mUiCallback.uiFailedWrite(mBluetoothGatt, mBluetoothDevice, mBluetoothSelectedService, characteristic, description + " STATUS = " + status);
            }
        };

        /**
         * Callback indicating the result of a descriptor write operation.
         *
         * @param gatt GATT client invoked {@link BluetoothGatt#writeDescriptor}
         * @param descriptor Descriptor that was written to the associated
         *                   remote device.
         * @param status The result of the write operation
         *               {@link BluetoothGatt#GATT_SUCCESS} if the operation succeeds.
         */
        @Override
        public void onDescriptorWrite(BluetoothGatt gatt, BluetoothGattDescriptor descriptor, int status)
        {
            Log.d("-----", "Wrote a descriptor");

            // Ready for next transmission
            processTxQueue();
        }
    };

    /* An enqueueable write operation - notification subscription or characteristic write */
    private class TxQueueItem
    {
        BluetoothGattCharacteristic characteristic;
        byte[] dataToWrite; // Only used for characteristic write
        boolean enabled; // Only used for characteristic notification subscription
        public TxQueueItemType type;
    }

    /**
     * The queue of pending transmissions
     */
    private Queue<TxQueueItem> txQueue = new LinkedList<TxQueueItem>();

    private boolean txQueueProcessing = false;

    private enum TxQueueItemType {
        SubscribeCharacteristic,
        ReadCharacteristic,
        WriteCharacteristic
    }

    /* queues enables/disables notification for characteristic */
    public void queueSetNotificationForCharacteristic(BluetoothGattCharacteristic ch, boolean enabled)
    {
        // Add to queue because shitty Android GATT stuff is only synchronous
        TxQueueItem txQueueItem = new TxQueueItem();
        txQueueItem.characteristic = ch;
        txQueueItem.enabled = enabled;
        txQueueItem.type = TxQueueItemType.SubscribeCharacteristic;
        addToTxQueue(txQueueItem);
    }

    /* queues enables/disables notification for characteristic */
    public void queueWriteDataToCharacteristic(final BluetoothGattCharacteristic ch, final byte[] dataToWrite)
    {
        // Add to queue because shitty Android GATT stuff is only synchronous
        TxQueueItem txQueueItem = new TxQueueItem();
        txQueueItem.characteristic = ch;
        txQueueItem.dataToWrite = dataToWrite;
        txQueueItem.type = TxQueueItemType.WriteCharacteristic;
        addToTxQueue(txQueueItem);
    }

    /* request to fetch newest value stored on the remote device for particular characteristic */
    public void queueRequestCharacteristicValue(BluetoothGattCharacteristic ch) {

        // Add to queue because shitty Android GATT stuff is only synchronous
        TxQueueItem txQueueItem = new TxQueueItem();
        txQueueItem.characteristic = ch;
        txQueueItem.type = TxQueueItemType.ReadCharacteristic;
        addToTxQueue(txQueueItem);
    }

    /**
     * Add a transaction item to transaction queue
     * @param txQueueItem
     */
    private void addToTxQueue(TxQueueItem txQueueItem) {

        txQueue.add(txQueueItem);

        // If there is no other transmission processing, go do this one!
        if (!txQueueProcessing) {
            processTxQueue();
        }
    }

    /**
     * Call when a transaction has been completed.
     * Will process next transaction if queued
     */
    private void processTxQueue()
    {
        if (txQueue.size() <= 0)  {
            txQueueProcessing = false;
            return;
        }

        txQueueProcessing = true;
        TxQueueItem txQueueItem = txQueue.remove();
        switch (txQueueItem.type) {
            case WriteCharacteristic:
                writeDataToCharacteristic(txQueueItem.characteristic, txQueueItem.dataToWrite);
                break;
            case SubscribeCharacteristic:
                setNotificationForCharacteristic(txQueueItem.characteristic, txQueueItem.enabled);
                break;
            case ReadCharacteristic:
                requestCharacteristicValue(txQueueItem.characteristic);
        }
    }

    private Activity mParent = null;
    private boolean mConnected = false;
    private String mDeviceAddress = "";

    private BluetoothManager mBluetoothManager = null;
    private BluetoothAdapter mBluetoothAdapter = null;
    private BluetoothDevice  mBluetoothDevice = null;
    private BluetoothGatt    mBluetoothGatt = null;
    private BluetoothGattService mBluetoothSelectedService = null;
    private List<BluetoothGattService> mBluetoothGattServices = null;

    private Handler mTimerHandler = new Handler();
    private boolean mTimerEnabled = false;
}

Nice snippet, thanks!

I noticed you could move this line
if (mBluetoothAdapter == null || mBluetoothGatt == null) return;

to your processTxQueue method and remove the corresponding code from these 3 methods to deduplicate code:

• writeDataToCharacteristic (replace with if (ch == null) return;)
• setNotificationForCharacteristic
• requestCharacteristicValue

@RafaelKr thanks! I forgot I'd even posted this, it's old. But I appreciate the feedback and hope it'll be useful for anyone else looking at this code.

@SoulAuctioneer, after 6 years :) i've found your BT class interesting. Please can you tell me how you used this 3 methods. Thanks.

• queueSetNotificationForCharacteristic
• queueWriteDataToCharacteristic
• queueRequestCharacteristicValue

Hope hearing from you.

@dononcharles this is very old code, so I hope you can find something more modern! I don't really understand your question about how you use these methods. But basically you should use these instead of their corresponding methods *without *the queue. e.g. instead of calling `setNotificationForCharacteristic`, use `queueSetNotificationForCharacteristic`.

…

On Mon, Jan 4, 2021 at 2:07 AM Komi Donon ***@***.***> wrote: ***@***.**** commented on this gist. ------------------------------ @SoulAuctioneer <https://github.com/SoulAuctioneer>, after 6 years :) i've found your BT class interesting. Please can you tell me how you used this 3 methods. Thanks. - queueSetNotificationForCharacteristic - queueWriteDataToCharacteristic - queueRequestCharacteristicValue Hope hearing from you. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <https://gist.github.com/ee4cb9bc0b3785bbdd51#gistcomment-3581506>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAEXBKDP5GVELRHLIRNKWWTSYGHNHANCNFSM4J3A72TQ> .