- **Goal**: Use BlueZ and an Bluetooth 4LE dongle to create a peripheral that advertises the bluetooth equivalent of &quot;Hello World&quot;.

- **Where I&#39;m At**: I&#39;ve currently got the BlueZ stack setup and downloaded, I can use the hci tool to recognize and see the Bluetooth dongle. I&#39;ve tinkered with hciconfig leadv but I&#39;m just not quite getting it/understanding what&#39;s going on.

- **What Help I Think I Need**: I need to get it to the next step. If anyone can either point me towards a good resource, walk me through this, or anything, It would be much appreciated. If I need to do additional leg(search)work I can but I&#39;ve scoured Google and SO with as many different derivatives of this question as I can think of.

*I tagged this as CoreBluetooth as well in hopes that maybe an iOS dev has tinkered with this at some point.

EDIT: In response to a comment, It seems prudent to state what my end goal is. I&#39;d ultimately like to advertise via the dongle the simplest of simple messages/signals and pick that up on an iOS device (CoreBluetooth). I&#39;ve been able to get the iOS side of things working well (tons of documentation compared to the Linux side of things) but that hard part for me is getting this adapter setup as a peripheral. The BlueZ stack is a terrible enigma for me.

EDIT: After more digging, I eventually stumbled upon this post: https://stackoverflow.com/questions/16052882/raspberry-pi-bluetooth-4-0-connection.
This has led me toward the topic of a GATT server, I&#39;ll continue pursuing this topic.

EDIT: Alright so my quest for learning goes on. Over the past couple of days I&#39;ve dived deeper into the hci*, sdptool, and gatttool tools. I&#39;ve gotten to the point of being able to set the adapter to advertise, &quot;hciconfig hci0 leadv&quot;. At this point, I can successfully &quot;see&quot; the adapter, but I cannot actually read anything off of it. I&#39;m not even seeing the friendly name. I&#39;ll keep trucking on but as always, any help/suggestions are more than welcome.

EDIT: Relevant Link, solid overview of Bluetooth LE pertaining to iOS.
https://developer.apple.com/library/content/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/AboutCoreBluetooth/Introduction.html#//apple_ref/doc/uid/TP40013257-CH1-SW1


LAST EDIT: Hey all, this link covers how to create an iBeacon using a Raspberry Pi + BlueZ...
http://www.wadewegner.com/2014/05/create-an-ibeacon-transmitter-with-the-raspberry-pi/

Use BlueZ Stack As A Peripheral (Advertiser)


I am currently working on an iOS application based on bluetooth low energy devices. In order to get a unique identifier to compare the peripherals got, I have to get the MAC address of the peripherals. 

It is observed that the UUID property of a peripheral device varies across iOS devices and also for the peripheral device to get a UUID, it will have to get connected to a master device at least once. Since I have to deal with check-in&#39;s I don&#39;t want to establish a connection. As I went through the bluetooth services portal, I found that the device information itself is a service, which couldn&#39;t be retrieved unless a connection has been established between the master iOS device and the peripheral bluetooth low energy device.

I found that in Android we get the entire information of the device, including its MAC address (using getAddress()) when we get the response from the device on scanning itself.

I didn&#39;t find any properties in CBPeripheral class related to the device address.
Another way to get a unique parameter would be to customize the advertisement data to send additional information regarding the device, which requires more work on firmware side.

So is there any way in iOS that I could get the MAC address of the bluetooth low energy peripheral without establishing a connection?

Any help would be greatly appreciated.


Get MAC address of bluetooth low energy peripheral in iOS

Android Bluetooth Low Energy API implements 1 method to connect to the device `connectGatt()` but 2 methods to close the connection `disconnect()` and `close()`.


Documentation says:

 - `disconnect()`: Disconnects an established connection, or cancels a connection attempt
       currently in progress.
   
 - `close()`: Application should call this method as early as possible after it is done with
         this GATT client.

The source code of [BluetoothGatt.java][1] shows that close() unregisters the application and disconnect() disconnect the client. However it does not say what that actually means. I mean, if there is only 1 way to connect to the client, why there are 2 ways to close/disconnect the connection?


  [1]: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/bluetooth/BluetoothGatt.java

Difference between close() and disconnect()?

I&#39;m trying to write an application to send messages over Bluetooth Low Energy, which will then be passed on by UART in my peripheral. I&#39;ve followed the steps [here](http://developer.android.com/guide/topics/connectivity/bluetooth-le.html) and the app scans for and finds the device successfully. However, connection using the BluetoothGatt = BluetoothDevice.connectGatt(context, autoconnect, callback) method fails, with logcat saying &quot;Failed to register callback&quot;.

Call made from:

    //device scan callback
    private BluetoothAdapter.LeScanCallback btScanCallback = new BluetoothAdapter.LeScanCallback() 
    {
        @Override
        public void onLeScan(final BluetoothDevice device, final int rssi, final byte[] scanRecord)
        {		
            some stuff
            currBtGatt = device.connectGatt(parentActivity, false, btGattCallback);
        }
    };

And the Gatt callback:

    //GATT callback
    private BluetoothGattCallback btGattCallback = new BluetoothGattCallback()
    {		
        @Override
        public void onConnectionStateChange(BluetoothGatt gatt, int status, int newState)
        {
            // if connected successfully
            if(newState == BluetoothProfile.STATE_CONNECTED)
            {
                //discover services
                updateStatus(&quot;Connected&quot;);
                gatt.discoverServices();
            }
            else if(newState == BluetoothProfile.STATE_DISCONNECTED)
            {
                updateStatus(&quot;Disconnected&quot;);
            }
        }
		
        @Override
        public void onServicesDiscovered(BluetoothGatt gatt, int status)
        {
            if(status == BluetoothGatt.GATT_SUCCESS)
            {
                //pick out the (app side) transmit channel
                currBtService = gatt.getService(uartUuids[0]);
                currBtCharacteristic = currBtService.getCharacteristic(uartUuids[1]);
            }
            else 
            {
                updateStatus(&quot;Service discovery failed&quot;);
            }
        }
    };

Logcat says:

    11-19 10:40:39.363: D/BluetoothAdapter(11717): stopLeScan()
    11-19 10:40:39.373: D/BluetoothGatt(11717): connect() - device: DC:6D:75:0C:0F:F9, auto: false
    11-19 10:40:39.373: D/BluetoothGatt(11717): registerApp()
    11-19 10:40:39.373: D/BluetoothGatt(11717): registerApp() - UUID=3ba20989-5026-4715-add3-a5e31684009a
    11-19 10:40:39.373: I/BluetoothGatt(11717): Client registered, waiting for callback
    11-19 10:40:49.373: E/BluetoothGatt(11717): Failed to register callback
    11-19 10:40:49.533: D/BluetoothGatt(11717): onClientRegistered() - status=0 clientIf=5
    11-19 10:40:49.533: E/BluetoothGatt(11717): Bad connection state: 0
    11-19 10:40:49.593: D/BluetoothGatt(11717): onClientConnectionState() - status=0 clientIf=5 device=DC:6D:75:0C:0F:F9
    11-19 10:40:49.593: W/BluetoothGatt(11717): Unhandled exception: java.lang.NullPointerException

Interestingly, my peripheral moves to a &quot;connected&quot; state (I have indication LEDs) and I can connect to it from the same phone with a demonstration application or with a PC BLE dongle. Any ideas appreciated.

[EDIT] the connectGatt method returns null, which I guess is expected.

[EDIT] On inspection of API 18 source code, it appears that the &quot;Failed to register callback&quot; message is delivered because the method registerApp() returns false because the registerClient() method of the IBluetoothGatt &quot;mService&quot; throws a remote exception, probably at the line:

    enforceCallingOrSelfPermission(BLUETOOTH_PERM, &quot;Need BLUETOOTH permission&quot;);

because the log message in the very next line is never seen. So it could be a permissions thing, except that the application _has_ bluetooth and bluetooth_admin permissions.

GATT callback fails to register

I&#39;m trying to do a lescan using hcitool on the raspberry pi. 

The command prints out 

    Set scan parameters failed: Input/output error. 

I&#39;m not sure, what exactly happens here. My iPhone is advertising here. 

I&#39;m using a BLE dongle from IOGear. 

However, if I restart my machine, it shows the a MAC address after I issue the `lescan` command, and starts showing the same error after I issue the lescan command a couple of more times. Is it like, the lescan command cannot be issued more than once? 

hcitool lescan shows I/O error

**Background**:

Ideally I would like my Android device to be scanning for Bluetooth Low Energy devices all the time an the ability to start an application whenever a new device with specific properties appears.

So the broadcast packet in BLE will for instance enumerate a set of services provided by the broadcasting device. An app would then be able to register an interest for certain services and automatically be started when a device with this services comes into range.

From what I understand this is not how the Android BLE API works? So how can I get something similar?

**Simplest possible example**:

I have a BLE sensor that logs ambient temperature over time. Whenever my Android phone is close enough I want to connect and download all the data, sending it to some cloud storage solution. This app would not need any GUI (at least not after configuration is done). But how should it run in the background without draining the battery, but still give me a fairly good chance of connecting the device quickly once it is in range?

**Question**:

Do I need to set a timer and wake the app every once in a while and then manually start scanning? What kind of intervals should I then choose. How long can I leave the scanner running without adversely affecting the battery?

**Possible solution**:

This is what I&#39;ve come up with so far.

 * A configuration activity to set the intervals and devices to scan for
 * The configuration activity will set up an WakefulBroadcastReceiver similar to the [Scheduler][1] example
 * When the receiver get&#39;s the onReceive event I start a BLE scan service (that I&#39;ve written) as a wakeful service.
 * The scan service starts scanning (with a registered callback).
 * The service might get adv reports that it can act upon
 * After a timeout the service will stop the scanner and end the wakeful service.

This works, but I&#39;m not sure it&#39;s the best way. I also don&#39;t know how small intervals I can have and still avoid destroying the battery life. What I would want is to start scanning every two minutes, scanning for 10-20 seconds. But I&#39;m afraid that would be rather frequently to wake up the device?

  [1]: https://android.googlesource.com/platform/developers/samples/android/+/d26c23e/background/alarms/Scheduler/

Creating background services for Bluetooth low energy on Android

I am writing a test app in iOS 7 with the Core Bluetooth API. When I am testing the application I found that I am getting the following warning message:

 &gt; TestBluetooth[626:60b] CoreBluetooth[API MISUSE] &lt;CBCentralManager: 0x16d4c230&gt; can only accept commands while in the powered on state

Later I debugged app and found that, warning is coming from the following line of code:
 
    [manager scanForPeripheralsWithServices:array options:scanOptions];

So can anyone please tell me why I am getting this message in the console? 

There are bluetooth 4.0 android devices around me, but this app is not discovering them as peripheral device. So why it is not discovering bluetooth 4.0 LE Android devices as peripherals?

iOS Core Bluetooth : Getting API MISUSE Warning

I am currently developing an application that will use Bluetooth Low Energy (testing on the Nexus 4). After getting started with the official BLE APIs in Android 4.3, I have noticed that after I connect a device for the first time I am rarely able to successfully connect to / communicate with that device or any other device again.

Following the guide [here](http://developer.android.com/guide/topics/connectivity/bluetooth-le.html), I can successfully connect to a device, scan services and characteristics, and read/write/receive notifications without any issues. However, after disconnecting and re-connecting, I am often unable to either scan services/characteristics or unable to complete a read/write. I can&#39;t find anything in the logs to indicate why this is happening.

Once this happens I have to uninstall the application, disable Bluetooth, and restart the phone before it will start working again.

Whenever a device is disconnected I make sure to call close() on the BluetoothGatt object and set it to null. Any insights?

---------
EDIT:&lt;br&gt;
Log dumps: For these logs I rooted my phone and upped the trace levels of related items in /etc/bluetooth/bt_stack.conf

[Successful connection][1] - First attempt after rebooting the phone and installing the app. I am able to connect, discover all services/characteristics, and read/write.

[Failed Attempt 1][2] - This is the next attempt after disconnecting from the successful connection above. It seems I was able to discover characteristics, but the first attempt to read returned a null value and disconnected soon thereafter.

[Failed Attempt 2][3] - An example where I am not even able to discover services/characteristics.

---------
EDIT 2:&lt;br&gt;
The device to which I am trying to connect is based on TI&#39;s CC2541 chip. I obtained a [TI SensorTag][4] (also based on the CC2541) to play around with and discovered that TI released [an android app][5] for the SensorTag yesterday. However, this app has &lt;b&gt;the same problem.&lt;/b&gt; I tested this on two other Nexus 4s with the same result: Connection to the SensorTag is successful the first or second time, but (according to the logs) fails to discover services thereafter, causing all sorts of crashes. I&#39;m starting to wonder if it&#39;s an issue with this specific chip?


  [1]: http://pastebin.com/wWrqsywZ
  [2]: http://pastebin.com/AhZq17bU
  [3]: http://pastebin.com/w0XjwDMW
  [4]: http://www.ti.com/ww/en/wireless_connectivity/sensortag/index.shtml?DCMP=sensortag&amp;HQS=sensortag-bn
  [5]: http://www.ti.com/tool/sensortag-sw?DCMP=lprf-stdroid&amp;HQS=sensortag-app-android

Android 4.3 Bluetooth Low Energy unstable

I&#39;d like to create my own iBeacon with some Bluetooth Low Energy dev kits. Apple has yet to release a specification for iBeacons, however, a few hardware developers have reverse Engineered the iBeacon from the AirLocate Sample code and started selling iBeacon dev kits. 

**So what is the iBeacon Bluetooth Profile?**

Bluetooth Low Energy uses GATT for LE profile service discovery. So I think we need to know the Attribute Handle, Attribute Type, Attribute Value, and maybe the Attribute Permissions of the iBeacon attribute. So for an iBeacon with a UUID of E2C56DB5-DFFB-48D2-B060-D0F5A71096E0, a major value of 1 and a minor value of 1 what would the Bluetooth GATT profile service be?

Here are some assumptions I&#39;ve made from the discussion on Apple&#39;s forums and through the docs.

1. You only need to see the profile service (GATT) of a Bluetooth peripheral to know it is an iBeacon.

2. The Major and Minor keys are encoded somewhere in this profile service


Heres some companies with iBeacon Dev Kits that seem to have this figure out already:

 - http://redbearlab.com/ibeacon/
 - http://kontakt.io/

  [1]: https://developer.apple.com/library/ios/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/BestPracticesForSettingUpYourIOSDeviceAsAPeripheral/BestPracticesForSettingUpYourIOSDeviceAsAPeripheral.html

Hopefully, in time we will have a profile posted on Bluetooth.org like these: https://www.bluetooth.org/en-us/specification/adopted-specifications

What is the iBeacon Bluetooth Profile

Trying to grasp a basic concept of how distancing with ibeacon (beacon/ Bluetooth-lowenergy/BLE) can work. Is there any true documentation on how far exactly an ibeacon can measure. Lets say I am 300 feet away...is it possible for an ibeacon to detect this?

Specifically for v4 &amp;. v5 and with iOS but generally any BLE device.

How does Bluetooth frequency &amp; throughput affect this? Can beacon devices enhance or restrict the distance / improve upon underlying BLE? 

ie

                   | Range	     | Freq       | T/sec      | Topo       |      
                   |–—–––––––––––|–—––––––––––|–—––––––––––|–—––––––––––|
    Bluetooth v2.1 | Up to 100 m | &lt; 2.481ghz | &lt; 2.1mbit  | scatternet |
                   |-------------|------------|------------|------------|
    Bluetooth v4   |     ?       | &lt; 2.481ghz | &lt; 305kbit  | mesh       |
                   |-------------|------------|------------|------------|
    Bluetooth v5   |     ?       | &lt; 2.481ghz | &lt; 1306kbit | mesh       |



Understanding ibeacon distancing

After upgrading to Android version 6.0 Bluetooth Low Energy (BLE) scanning will only work if Location services are enabled on the device. See here for reference: https://stackoverflow.com/questions/33043582/bluetooth-low-energy-startscan-on-android-6-0-does-not-find-devices/33045489#33045489

Basically, you need to have the permission enabled for the app as well as on for the phone.  Is this a bug? Is it possible to scan without location services actually enabled? I don&#39;t want to have to have location for all my apps. 

**EDIT** 
I failed to mention that I am using the `startScan()` method in `BluetoothLeScanner` provided in API 21. I am okay with the course and fine location permissions in the manifest that this method require. I just don&#39;t want the users of my app to have to enable location services on their device (GPS, etc.) to use my app. 

Previously, the `startScan()` method would run and return results with the Location services disabled on the phone. On Marshmallow, however, the same application would &quot;scan&quot; but silently failed and returned no results when location services were not enabled on the phone and course/fine location permissions were still in the manifest.

Location needs to be enabled for Bluetooth Low Energy Scanning on Android 6.0

I&#39;m trying to make an application which uses the **new Bluetooth Low Energy API** of Android. For this, I started with the BLE sample coming with **API level 18**. 

As I read that Android can not act as a Peripheral, I put the Android phone in central mode, scanning for **BLE devices** around it. For this purpose, I made some testing with a Nordic Platform simulating a Heart Sensor. Everything works in a perfect way!

After this, I try to pick an **iPhone (iOS 7 beta 4)** and put it in a Peripheral way and simulating a **Heart Rate sensor** as the previous testing. The Android app is able to see the device and connect to it. But after the connection is active, the 2 devices disconnect from each other in 3-4 seconds. In addition to that, when I call discoverServices() on Android side, no callback is triggered! In some cases the Android device receives the &quot;Connected&quot; event even if iOS Bluetooth chip is Off. This is very strange. To prove that, I put the **Nordic Board in Central mode** and I was correctly able to connect to the iOS device with no problems. 

What could it be? There are some limitations on Android or iOS that don&#39;t permit to connect from an Android to an iOS or viceversa?

Thanks.

EDIT: After some hard testing, I raised an issue on the AOSP page. It can be checked [here][1]


  [1]: https://code.google.com/p/android/issues/detail?can=2&amp;start=0&amp;num=100&amp;q=&amp;colspec=ID%20Type%20Status%20Owner%20Summary%20Stars&amp;groupby=&amp;sort=&amp;id=58725

How to connect Android device to an iOS device over BLE (Bluetooth Low Energy)

Can an Android device act as an iBeacon and figure out when other Android devices come in its range? Do those other Android devices need to have Bluetooth turned on?

If a customer comes into my shop and he doesn&#39;t have my app installed on his device, can iBeacon work, or must he install the app first? There are so many customers are visiting our shop daily, but if they don&#39;t have my app installed, does the iBeacon concept work?

Can an Android device act as an iBeacon?

Device used for testing: Nexus 4, Android 4.3

Connection is working fine but the `onCharacteristicChanged`Method of my callback is never called. However I am registering for notifications using `setCharacteristicNotification(char, true)` inside `onServicesDiscovered` and that function even returns true.

Device log (there are actually _no_ messages at all when notifications _should_ appear / are sent via the Bluetooth device):

    07-28 18:15:06.936  16777-16809/de.ffuf.leica.sketch D/BluetoothGatt: setCharacteristicNotification() - uuid: 3ab10101-f831-4395-b29d-570977d5bf94 enable: true
    07-28 18:15:06.936    4372-7645/com.android.bluetooth D/BtGatt.GattService: registerForNotification() - address=C9:79:25:34:19:6C enable: true
    07-28 18:15:06.936    4372-7645/com.android.bluetooth D/BtGatt.btif: btif_gattc_reg_for_notification
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1018
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.GattService: onRegisterForNotifications() - address=null, status=0, registered=1, charUuid=3ab10101-f831-4395-b29d-570977d5bf94
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1016
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1018
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.GattService: onRegisterForNotifications() - address=null, status=0, registered=1, charUuid=3ab10102-f831-4395-b29d-570977d5bf94
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1016
    07-28 18:15:06.946    4372-7684/com.android.bluetooth E/bt-btif: already has a pending command!!
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1013
    07-28 18:15:06.946    4372-7684/com.android.bluetooth E/bt-btif: already has a pending command!!
    07-28 18:15:06.946    4372-7645/com.android.bluetooth D/BtGatt.btif: btgattc_handle_event: Event 1013
    07-28 18:15:06.946    4372-7684/com.android.bluetooth E/bt-btif: already has a pending command!!
    07-28 18:15:06.976    4372-7645/com.android.bluetooth D/BtGatt.btif: btif_gattc_upstreams_evt: Event 9

GATT Notifications work fine using iOS and the app basically does the same as on Android (registering for notification etc.).

Has anyone else experienced this with a possible solution?

Android BLE API: GATT Notification not received

I am looking into the possibility to use multiple iBeacons to do a &#39;rough&#39; indoor position location. The application is a kind of &#39;museum&#39; setting, and it would be easier to be able to form a grid with locations for the different objects then individual beacons (although that might not be impossible too).

Are there examples, experiences, with using multiple beacons to triangulate into some kind of location, or some logic to help me on the way to write it myself?

Triangulate example for iBeacons

Is it possible to run an iOS 7 device as a Bluetooth LE peripheral (iBeacon) and have it advertise in the background?  I have been able to get it to advertise in the foreground with the code below and can see it from another iOS device but as soon as I go back to the home screen it stops advertising.  I did add the bluetooth-peripheral background mode in the plist but that didn&#39;t seem to help although I do get the prompt saying the device wants to use bluetooth in the background.  Am I doing something wrong or is this just not possible in iOS 7?

    peripManager = [[CBPeripheralManager alloc] initWithDelegate:self queue:nil];

    - (void)peripheralManagerDidUpdateState:(CBPeripheralManager *)peripheral
    {
      if (peripheral.state != CBPeripheralManagerStatePoweredOn) {
          return;
      }
    
      NSString *identifier = @&quot;MyBeacon&quot;;
      //Construct the region
      CLBeaconRegion *beaconRegion = [[CLBeaconRegion alloc] initWithProximityUUID:uuid identifier:identifier];
    
      //Passing nil will use the device default power
      NSDictionary *payload = [beaconRegion peripheralDataWithMeasuredPower:nil];
    
      //Start advertising
      [peripManager startAdvertising:payload];
    }

Here is the code that is on the receiving/listening end:

    - (void)locationManager:(CLLocationManager *)manager didRangeBeacons:(NSArray *)beacons
               inRegion:(CLBeaconRegion *)region
    {
    //Check if we have moved closer or farther away from the iBeacon…
    if (beacons.count &gt; 0) {
        CLBeacon *beacon = [beacons objectAtIndex:0];
        
        switch (beacon.proximity) {
            case CLProximityImmediate:
                [self log:[NSString stringWithFormat:@&quot;You&#39;re Sitting on it! %li&quot;, (long)beacon.rssi]];
                break;
            case CLProximityNear:
                [self log:[NSString stringWithFormat:@&quot;Getting Warmer! %li&quot;, (long)beacon.rssi]];
                break;
            default:
                [self log:[NSString stringWithFormat:@&quot;It&#39;s around here somewhere! %li&quot;, (long)beacon.rssi]];
                break;
        }
    }
    }

Run iPhone as an iBeacon in the background

I am able to send data upto 20 bytes by connecting to an external BLE device. How do I send data greater than 20 bytes. I have read that we have to either fragment the data or split characteristic to required parts. If I assume my data is 32 bytes, could you tell me changes I need to make in my code to get this working? Following are the required snippets from my code:

    public boolean send(byte[] data) {
        if (mBluetoothGatt == null || mBluetoothGattService == null) {
            Log.w(TAG, &quot;BluetoothGatt not initialized&quot;);
            return false;
        }

        BluetoothGattCharacteristic characteristic =
                mBluetoothGattService.getCharacteristic(UUID_SEND);

        if (characteristic == null) {
            Log.w(TAG, &quot;Send characteristic not found&quot;);
            return false;
        }

        characteristic.setValue(data);
        characteristic.setWriteType(BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE);
        return mBluetoothGatt.writeCharacteristic(characteristic);
    }

This is the code I used for sending the data. The &quot;send&quot; function is used in the following onclick event.

    sendValueButton = (Button) findViewById(R.id.sendValue);
        sendValueButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String text = dataEdit.getText().toString();                           
                yableeService.send(text.getBytes());
            }
        });

When the `String text` is greater than 20 bytes then only the first 20 bytes are received. How to rectify this?

To test sending multiple characteristics I tried this:

    sendValueButton = (Button) findViewById(R.id.sendValue);
    sendValueButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String text = &quot;Test1&quot;;                           
            yableeService.send(text.getBytes());

            text = &quot;Test2&quot;;                           
            yableeService.send(text.getBytes());

            text = &quot;Test3&quot;;                           
            yableeService.send(text.getBytes());
        }
    });
But I only received &quot;Test3&quot; i.e. the last characteristic. What mistake did I commit? I am new to BLE so please ignore any naiveness


***Edit:***

***After accepting answer*** for anyone who views this later.

There are **two** ways to accomplish this.
1. Split up your data and write in a loop as the selected answer does.
2. Split up your data and write using callback i.e. `onCharacterisitcWrite()`. This will save you from errors if there were any during writing.

But ***most important*** between the writes use a `Thread.sleep(200)` if you are only writing and not waiting for a response from the firmware. This will ensure that all of your data reaches. Without the `sleep` I was always getting the last packet. If you notice the accepted answer he has also used `sleep` in between.

All Bluetooth Lowenergy Solutions on Gang of Coders

Total of 17 Bluetooth Lowenergy Solutions