Bluetooth Connection

Owned by Ricardo Rufino
Last updated: Jan 03, 2016
5 min read

In this tutorial we show how to communicate using Bluetooth, there are simple and inexpensive modules that can be connected to the Arduino / similar.

Will not be required to use any particular library, because these modules operate using a Serial communication

Requirements

If you are using Linux, you must install the following dependencies:

sudo apt-get install bluetooth libbluetooth-dev bluez bluez-tools

Scan bluetooth devices (linux):

hcitool scan


Hardware Setup:

 

JY-MCU Bluetooth Module. It is a cheap Bluetooth module. (see HC-06 pinout)  (I got from here)

 

The JY-MCU module communicates with the Arduino via a serial connection. It has four pins that we will be using:

  • VCC is used to power the module.  It needs to be connected to the Arduino 5v pin.
  • GND is the ground pin. It needs to be connected to the Arduino Ground pin
  • TXD is used to send data from the module to the Arduino. It needs to be connected to the serial receive pin (RX) of the Arduino, which is pin 0 in case of the Uno. If you are using a different Arduino board, check its schematics to make sure you have the right pin.
  • RXD is used to receive data from the Arduino. It needs to be connected to the the Arduino serial transmit pin (TX) , which is pin 1 in the case of Arduino Uno.
  • We will not be using the “STATE” and the “KEY” pins of the Bluetooth module, so they will not be connected.

 

If you have hardware like LaunchPad see the session: EnergiaIDE

On this module, as you can see from the photo above, the TX line is rated at 3.3V. This means that even though we can power the module with 5 volts from the Arduino, the communication lines from and to the module are supposed to be at 3.3 volts.

Receiving data from the Arduino is where we need to do more work. The RX line of the Arduino Uno is running at 5V, so we will be sending a higher voltage on the Bluetooth’s module RX line, than suggested by the label. This may damage the Bluetooth module permanently!

I'm not using any voltage divider and is working properly, but if you do not want to risk burning your module, see this:


Other option:




Upload example to Arduino.

Use BluetoothConnection from Examples menu of Arduino IDE.

The example is virtually identical of USB example.

Before uploading to the arduino, disconnect bluetooth module pins 0 (RX) and 1 (TX), as they are the same ones used by the USB communication and you may have problems if you do not use the voltage divider

 

If you are using Leonardo, use:  ODev.begin(Serial1, 9600);

Connection with JAVA.

Pair Devices

Pair the module with your PC (or Android/Raspberry). The defaults for the Bluetooth module are:
Default Name: linvor
Default Pairing code: 1234

On some operating systems when you run the JAVA example, will open a pairing dialog.

If it does not you must add the device manually (run: bluetooth-wizard ) or from networks/bluetooth manager

Auto Paring (linux):

bluetooth-agent 1234 &

Basic Usage

Use the address found and add an output connection:

addOutput(Connections.out.bluetooth("00:13:03:14:19:07"));
Or: connect(Connections.out.bluetooth("00:11:06:14:04:57"));

You can also automatically connect to the first available device:

Note that this will be very slow because it will do the scan and will take the first bluetooth device found (can be up to your phone!)

connect(Connections.out.bluetooth());


Complete Example
public class BlinkDeviceDemo extends SimpleDeviceManager {
    public static void main(String[] args) throws Exception {
        new BlinkDeviceDemo();
    }
    public BlinkDeviceDemo() throws Exception {
        Device led = new Device(1, Device.DIGITAL);
        connect(Connections.out.bluetooth("00:11:06:14:04:57"));
        while(true){
            led.on();
            delay(500);
            led.off();
            delay(500);
        }
    }
}

Basically what we need to change is the type of connection to bluetooth

Alternative Hardware Setup

If you need to use other Arduino ports, you can use the SoftwareSerial library, is an example:



Use SoftwareSerial with Bluetooth in order to make it easier to program your Arduino and debug your code when using the Bluetooth module.


Bluetooth------------ Arduino
    GND      ------   GND
    3.3      do not connect
    5.0      ------    5V
    RXD      ------    D11
    TXD      ------    D10
    KEY      do not connect

Software / Firmware

You need use: BluetoothConnectionSoft example.

(Arduino/Similar) basic changes
// You need to make only those changes:
#include <SoftwareSerial.h>

void setup{
	ODev.begin(9600, 10, 11); 
}

In the Java side, you not need change anything

Energia IDE (LaunchPad Hardware)

The Energy IDE is an adaptation of the Arduino libraries to work with the hardware of the LaunchPad. See the supported platforms at:
http://energia.nu/
https://github.com/energia/Energia

In this example we use: LM4F120

Hardware Setup

Do not forget that the connection is RX -> TX and TX -> RX.

Software / Firmware

You need use: EnergiaLaunchPadBasic example.

Change to: Serial1 (Hardware UART on PC4, PC5 pins)

EnergiaLaunchPadBasic.ino (changes)
DeviceConnection deviceConnection(Serial1);

In the Java side, you not need change anything


References