Android - Connect to a Bluetooth module

Question

I have to develop an Android app to connect to a Bluetooth module that is connected to a board. My goal is to send and receive data to this board.

I'm currently able to enable the Bluetooth on my phone, to pair to the Bluetooth module but I don't know how to connect and send/receive data to this module.

Most of examples explain how to create a server and a client to communicate via sockets. Is it the good way for me? As described here : https://developer.android.com/guide/topics/connectivity/bluetooth.html#java

Answer 1

Do it like in the Example: https://developer.android.com/guide/topics/connectivity/bluetooth.html#example_1

Note that you will probably need to know what kind of service /profile the module provides. Often, generic modules/devices use the Serial Port Profile (SPP).

You use createInsecureRfcommSocketToServiceRecord() or createRfcommSocketToServiceRecord() to connect.

Which UUID you need depends on the actual service the module provides. For SPP see eg How to find the UUID of serial port Bluetooth device? :

The short, 16-bit UUID for SPP is

0x1101

the full UUID is

"00001101-0000-1000-8000-00805f9b34fb"

So, on Android, you'd use

final UUID SPP_SERVICE_UUID = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");

final BluetoothSocket socket = device.createRfcommSocketToServiceRecord( SPP_SERVICE_UUID );

socket.connect();

final InputStream is = socket.getInputStream();
final OutputStream os = socket.getOutputStream();

// Send data to output stream and/or receive data from input stream
// ...

socket.close(); // Disconnect

Answer 2

Following is a method:

• create service class which communicate every time when it is
  connected to that device.

• register that service into your main activity through broadcast update. then scan you Bluetooth devices(after validating permissions) and connect it,
  note that connection code must be in your serviceclass(all communication with device is through service class).

• after that you can sent data to and from the Bluetooth device.

Here attaching an example for you for working with BLE,Created by Nordic Semiconductor Click Here