This project is mainly based on mobile phone communication with Bluetooth and Controlling the Device from mobile using Bluetooth. Bluetooth  is a wireless technology is becoming a popular standard in the communication arena, and it is one of the fastest growing fields in the wireless technologies. It is convenient, easy to use and has the bandwidth to meet most of today’s demands for mobile and personal communications. Bluetooth technology handles the wireless part of the communication channel; it transmits and receives data wirelessly between these devices. It delivers the received data and receives the data to be transmitted to and from a host system through a host controller interface (HCI). The most popular host controller interface today is either a UART or a USB .Here, I will only focus on the UART interface, it can be easily show how a Bluetooth module can be integrated on to a host system through a UART connection and provide the designer an optimal solution for Bluetooth enabled systems. Here, I will show two examples of hardware interface between Bluetooth wireless technology and UART. One example shows an interface between a Bluetooth and a PC via UART, and the other example shows an interface between a Bluetooth and a Microcontroller via Mobile.

Concept

This project is mainly based on mobile phone communication with the Microcontroller through Bluetooth, here we are using the Android based mobile, and to communicate with the controller we need the supporting software installed in the mobile phone. Bluetooth SPP software must be installed in it. Connect the Bluetooth  with microcontroller using the serial port communication. Then dump the following code in flash memory of controller, open the Bluetooth SPP software it asks for pairing with the Bluetooth and after pairing the mobile with Bluetooth then start entering the message whenever the message ‘3’ is entered and sent the relay will be switched ON and if we send ‘4’ Relay is switched OFF. Using the Relay we can switch ON /OFF the electrical device.

Demonstration Video

Block Diagram

Hardware requirements

• 8051 Microcontroller
• Power Supply (9V Adaptor, 5V Adaptor)
• Bluetooth module
• Relay interface (user can interface any electrical device according to their Application)
• Mobile phone with Android OS

Software requirements

• Programming Language: Embedded C
• KEIL U Vision IDE
• Flash magic
• Bluetooth Spp software

Connect the Bluetooth device to the Microcontroller

To connect the Bluetooth device, you will need to find the Rx and TX pins on your microcontroller. Make sure that you cross the wires by connecting the Rx pin from your Bluetooth device to the TX pin on the microcontroller, and the TX pin from your Bluetooth device to the Rx pin on the microcontroller. Install the Bluetooth SPP software in Android based Mobile and pair the device and start the communication between Mobile and Microcontroller Bluetooth SPP provides Bluetooth connectivity for all android apps

• Install Bluetooth SPP software in Mobile
• Search for Bluetooth device
• Configure and pair the Bluetooth device Acquire data via soft keyboard and send the data through Bluetooth.

Lets us see the communication between Bluetooth Module pairs with Microcontroller & Mobile with Microcontroller as discussed below

Settings for Communication between mobile and microcontroller

Android Application Based Mobile

Install Bluetooth spp application software in Mobile

Bluetooth Setting with 8051

Settings for Communication between Bluetooth pairs with microcontroller

To communicate the Bluetooth with the PC we need to set the following settings in the HyperTerminal

• 9600 Baud Rate
• No parity
• 8 data bits
• Hardware flow control
• 1 Stop bit

Connect the Bluetooth  module 1 with the PC and connect the Bluetooth  module 2 with microcontroller dump the Hex file to controller and start pairing the Bluetooth device after the device is paired the communication happens. User can see the output on HyperTerminal

Hyper terminal

• From the Start menu select programs\Accessories\Communications\HyperTerminal or perform a search in My Computer for “HyperTerminal”

• Type in a connection identifier name say “Test1” and click OK. The only restriction here is it cannot be a
     – Device name e.g. “COM1”
     – You will then be presented with the following dialogue box

• Here it is possible to choose the COM port to test using the drop down box. In this example we will use the onboard port COM1. Click OK.
• The next dialogue box will ask for the Port Communication Settings

Bluetooth setting with PC

#include
sbit Fan=P1^0;
sbit Light=P1^1;
sbit TV=P1^2;
 char str;
 char Charin=0;
void delay(int time)
{
 unsigned int i,j;
 for(i=0;i<time;i++)
 for(j=0;j<1275;j++);
}
void Serialwrite(char byte)
{
  SBUF=byte;
  while(!TI);
  TI=0;
}
void Serialprintln(char *p)
{
  while(*p)
  {
    Serialwrite(*p);
    p++;
  }
  Serialwrite(0x0d);
}
void Serialbegin()
{
   TMOD=0x20;
   SCON=0x50;
   TH1=0xfd;
   TR1=1;
}
void main()
{
  P1=0x00;
  Serialbegin();
  Serialprintln("Sys ready...");
  delay(50);
  while(1)
  {
    while(!RI);
    Charin=SBUF;
    str=Charin;
    RI=0;
      if(str=='A')
      {
        Fan=1;
        Serialprintln("     Fan ON");
        delay(50);
      }
      else if(str=='a')
      {
        Fan=0;
        Serialprintln("    Fan OFF");
        delay(50);
      }
       else if(str=='B')
      {
        Light=1;
        Serialprintln("   Light ON");
        delay(50);
      }
       else if(str=='b')
      {
        Light=0;
        Serialprintln("Light OFF");
        delay(50);
      }
       else if(str=='C')
      {
        TV=1;
        Serialprintln("      TV ON");
        delay(50);
      }
       else if(str=='c')
      {
        TV=0;
        Serialprintln("     TV OFF");
        delay(50);
      }
      str=0;
  }
}