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Topic: Android Bluetooth to Arduino (Read 111910 times) previous topic - next topic


Hello everybody !

I'm quite new to the world of Arduino, but since the beginning I wanted to use my phone (an Android) to control my Arduino through Bluetooth. (I'm also a beginner to Android by the way).

I did tones of research online in order to find something relevant and simple in order to do that. But I miserably failed.
But since patience is a virtue, I managed to gather information from almost everywhere and found this.

Without any pretension, here is a short how-to tutorial.
Maybe this post will help, maybe not, but at least I tried  ^_^.

You need a Bluetooth Adapter plugged to your Arduino obviously.
For the Arduino code, I simply used the blink code and mixed it with Serial.read() function.

I'm not gonna explain how android works but here's the link to download the IDE.

Before anything, I want to add something, I'm not a pro in programming, like not at all, and I'm not a native English speaker, so I apologize for the mistakes I will make and for the non-scholarly terms I will use. (Remember that while reading, please).

Since I just want to use my App with my arduino, I hardcoded its Mac Address in the code.

First thing first you're gonna need to test if the bluetooth in your phone is enabled or not and if you can use it.

Code: [Select]

private void CheckBt() {
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

if (!mBluetoothAdapter.isEnabled()) {
Toast.makeText(getApplicationContext(), "Bluetooth Disabled !",
                   /* It tests if the bluetooth is enabled or not, if not the app will show a message. */

if (mBluetoothAdapter == null) {
"Bluetooth null !", Toast.LENGTH_SHORT)

You can invoke that method in the onCreate method or whenever you want to (before trying to make a connection obviously).

The connect part is quite simple, in that case the method was triggered by clicking on a button :

Code: [Select]

public void Connect() {
BluetoothDevice device = mBluetoothAdapter.getRemoteDevice(address);
Log.d("", "Connecting to ... " + device);
try {
                        btSocket = device.createRfcommSocketToServiceRecord(MY_UUID);
/* Here is the part the connection is made, by asking the device to create a RfcommSocket (Unsecure socket I guess), It map a port for us or something like that */
Log.d("", "Connection made.");
} catch (IOException e) {
try {
} catch (IOException e2) {
Log.d("", "Unable to end the connection");
Log.d("", "Socket creation failed");

               /* this is a method used to read what the Arduino says for example when you write Serial.print("Hello world.") in your Arduino code */

Then the method to actually Send stuff to the arduino.

Code: [Select]

private void writeData(String data) {
try {
outStream = btSocket.getOutputStream();
} catch (IOException e) {
Log.d(TAG, "Bug BEFORE Sending stuff", e);

String message = data;
/* In my example, I put a button that invoke this method and send a string to it */
byte[] msgBuffer = message.getBytes();

try {
} catch (IOException e) {
Log.d(TAG, "Bug while sending stuff", e);

Finally the part where the Android application actually read data just like I said earlier.

Code: [Select]

public void beginListenForData()   {
try {
inStream = btSocket.getInputStream();
} catch (IOException e) {

        Thread workerThread = new Thread(new Runnable()
            public void run()
               while(!Thread.currentThread().isInterrupted() && !stopWorker)
                        int bytesAvailable = inStream.available();                       
                        if(bytesAvailable > 0)
                            byte[] packetBytes = new byte[bytesAvailable];
                            for(int i=0;i<bytesAvailable;i++)
                                byte b = packetBytes[i];
                                if(b == delimiter)
                                    byte[] encodedBytes = new byte[readBufferPosition];
                                    System.arraycopy(readBuffer, 0, encodedBytes, 0, encodedBytes.length);
                                    final String data = new String(encodedBytes, "US-ASCII");
                                    readBufferPosition = 0;
                                    handler.post(new Runnable()
                                        public void run()
                                        if(Result.getText().toString().equals("..")) {
                                        } else {
                                        /* You also can use Result.setText(data); it won't display multilines
                                    readBuffer[readBufferPosition++] = b;
                    catch (IOException ex)
                        stopWorker = true;


I took it online so I can't really tell you much about that other that it works.
From what I can understand this method creates a Thread that checks whether there's something or not in the buffer and display it in the Result TextView.

Don't forget to add those two lines in your manifest.

    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
    <uses-permission android:name="android.permission.BLUETOOTH"/>

Otherwise the app will crash.

Here's the full code :

There you go.

Hope it wasn't too useless and boring and maybe somewhat interesting, it helped me to understand Bluetooth SPP.

Maybe it will be simpler to upload the project so, here it is.


Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)



ok this may sound dumb...  I have the android SDK.  where do I put this code?


It might be a bit late, but the code goes in your Main Activity at least that's where I put it.
If you want to learn more about Android Development, here's a pretty nice video tutorial :

The website covers lots of programming languages.
(I don't own this website, nor i'm related to it, I just find it very good and pretty complete at least to start)

In addition, for those who might be interested, I used a Bt Adapter called JY-MCU, it's the cheapest one I could find on the bay.
It works fine, it's a slave device though, so you can't scan nor initiate a connection with it.


Do you know if this bluetooth module will work with iOS? For that matter, are there any bluetooth modules out there that work with both Android and iOS?


Sep 03, 2013, 08:55 pm Last Edit: Sep 03, 2013, 08:59 pm by the1cyrus Reason: 1
Hey Jon17,

If you have the project with this code and its other parts available could you post a link to download it? I'm having some problems getting mine to not crash when it opens.


I second the1cyrus's request. Please do post the entire project, I too am having troubles fixing some errors.


I'm pretty new to this and I don't know if this is a dumb question but what is the code supposed to be in the activity_main.xml of this project?


Hello everyone !

I'm sorry I didn't answer earlier, lots of things to do.

I have my project uploaded in my Google Drive, here is the link :

I'm not realy sure it's the good project, you'll have to tell me since I'm not on the right computer to test it.
Hope it'll suit you.

Have a good evening !


hi! the android app. will still work if i will use this ? http://appinventor.mit.edu/ thanks


you could try this.https://play.google.com/store/apps/details?id=com.lovejoysa.btswitch


Thanks for sharing!

I have only used AppInventor so far fr basic Android apps. It is simple to design a basic interface with a few buttons. Of course, you need to use proper development tools for larger projects.  There is a free online course coming up on Coursera: for Android development that may be interesting:

I started messing around with Bluetooth recently as well and created a small robot that I can control from my phone. I am documenting my progress here:
Arduino experiments, resources and hacks http://42bots.com


I'm very interested in this. I have several projects for the Arduino for which I need color screens, and having touchscreen controls would be a plus. Cheap Android tablets can be had for as low as $50, versus $80 or more for a 7 inch touchscreen.

At the moment, I have nothing more useful to add. I'm a rank newbie to Arduino programming, most of my programming experience was in solder and to a lesser extent in Basic.
Steve Greenfield AE7HD
Drawing Schematics: tinyurl.com/23mo9pf - tinyurl.com/o97ysyx - https://tinyurl.com/Technote8
Multitasking: forum.arduino.cc/index.php?topic=223286.0
gammon.com.au/blink - gammon.com.au/serial - gammon.com.au/interrupts


I'm a rank newbie to Arduino programming, most of my programming experience was in solder and to a lesser extent in Basic.

You don't need to learn Android programming to control your Arduino.  Check out pfodDesigner

pfodDesigner lets you build custom Android Menus and then generates the Arduino sketch that servers them up, via pfodApp, and handles the users button presses.  You only need to add the action code to the sketch.

Here is an example menu designed by pfodDesigner.  You can format the colour, text, number of buttons, font size and font style.
No Android programming required.

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