Bluetooth controller automation system using 8051 ~ Riyaz Basha's Blog DBRT(2016/17)

Bluetooth controller automation system using 8051

Imagine that you can control the electronic appliances of your home from anywhere inside the house, just using your Smart phone. In this project, we will use wireless Bluetooth technology to control the Home Electronic Appliances through a Android Phone. Bluetooth has a range of 10-15 meters, so that you can switch ON and OFF any electronic appliance within the range.

Here we have used 8051 microcontroller with a Bluetooth module, for wirelessly receive the data, sent from the Android Phone. So that microcontroller can Turn ON and OFF the home appliances accordingly.

Main Components

8051 microcontroller
Bluetooth Module HC05
Relay
ULN2003
Bulb
Holder
Wire
IC 7805
Android phone
Bluetooth controller app Android app
10uf capacitor
1000uf capacitor
10K resistor
1k resistor
Power Supply

Bluetooth Module:

HC-05 Bluetooth module consists two things one is Bluetooth serial interface module and a Bluetooth adaptor. Bluetooth serial module is used for converting serial port to Bluetooth.

How to operate Bluetooth module?

You can directly use the Bluetooth module after purchasing from market, because there is no need to change any setting of Bluetooth module. Default baud rate of new Bluetooth module is 9600 bps. You just need to connect rx and tx to controller or serial converter and give 5 volt dc regulated power supply to module.

Bluetooth module has two modes one is master mode and second one is slave mode. User can set either mode by using some AT commands. Even user can set module’s setting by using AT command. Here is some commands uses are given:

First of all user need to enter AT mode with 38400 bps baud rate by pressing EN button at Bluetooth module or by giving HIGH level at EN pin. Note: all commands should ends with \r\n (0x0d and 0x0a) or ENTER KEY from keyboard.

After it if you send AT to module then module will respond with OK

AT → Test Command

AT+ROLE=0 → Slave Mode select

AT+ROLE=1 → Master Mode select

AT+NAME=xyz → Set Bluetooth Name

AT+PSWD=xyz → Set Password

AT+UART=<value1>,<value2>,<value3> → set Baud rate

Eg. AT+UART=9600,0,0

Pin Description of accelerometer:

STATE → Open
Rx → Serial receiving pin
Tx → Serial transmitting pin
GND → ground
Vcc → +5volt dc
EN → to enter in AT mode

Working Explanation:

In this project we have used 8051 microcontroller for controlling the whole process of this project. And a Bluetooth module is used for controlling the home appliances wirelessly. Home appliances will turned ON and OFF when user will touch button in the Bluetooth mobile app in Android mobile phone. To run this project, first we need to download Bluetooth app form Google play store. We can use any Bluetooth app that can send data using Bluetooth. Here are some apps name that can be used:

Circuit Diagram and Explanation

Circuit connections of this project are very simple. Bluetooth module’s Rx and Tx pins are directly connected to the Tx and Rx pins of Microcontroller. Three 5 volt relays are used as a switch for turning On and Off the home appliances running on AC mains. And a relay driver ULN2003 is used for driving relays. Fan, Light and TV are connected at P2.1, P2.2 and P2.3 via relays and relay driver. An 11.0592 MHz Crystal oscillator is used in this circuit for generating clock signal for microcontroller. And a 5 volt voltage regulator LM7805 is used for provide 5 volt for the whole circuit.

Bluetooth Controlled Home Automation System Circuit Diagram

Program Explanation:

In this program, first of all we have included header file and defines input, output pins and variables.

#include<reg51.h>

sbit Fan=P2^0;
sbit Light=P2^1;
sbit TV=P2^2;

 char str;
 char Charin=0;

After this we have created a function for delay.

void delay(int time)
{
  unsigned int i,j;
  for(i=0;i<time;i++)
  for(j=0;j<1275;j++);
}

Here we have some functions that we have used in our program. In this we have configured 9600bps baud rate at 11.0592MHz Crystal Frequency.

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;
}

After this, in main program we have initialized UART and monitored the SBUF register for receiving the data. Then data is matched and compared with predefined values and relative operation has been performed.

void main()
{
  P2=0x00;
  Serialbegin();
  Serialprintln("System Ready...");
  delay(50);
  while(1)
  {
    while(!RI);
    Charin=SBUF;
    str=Charin;
    RI=0;
      if(str=='1')
      {
        Fan=1;
        Serialprintln(" Fan ON");
        delay(50);
      }
      else if(str=='2')
      {
        Fan=0;
        Serialprintln(" Fan OFF");
        delay(50);
      }

So that’s how we can create a whole system for the house and can connect all the AC appliances to the 8051 microcontroller using Relays. And this bluetooth controlled home automation system can be operated from a Smart phone.

Code:

#include<reg51.h>

sbit Fan=P2^0;
sbit Light=P2^1;
sbit TV=P2^2;

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()
{
P2=0x00;
Serialbegin();
Serialprintln("System Ready...");
delay(50);
while(1)
{
while(!RI);
Charin=SBUF;
   str=Charin;
RI=0;
   if(str=='1')
   {
   Fan=1;
       Serialprintln(" Fan ON");
       delay(50);
   }
   else if(str=='2')
   {
   Fan=0;
       Serialprintln(" Fan OFF");
       delay(50);
   }

   else if(str=='3')
   {
   Light=1;
       Serialprintln(" Light ON");
       delay(50);
   }

   else if(str=='4')
   {
   Light=0;
       Serialprintln(" Light OFF");
       delay(50);
   }

   else if(str=='5')
   {
   TV=1;
       Serialprintln(" TV ON");
       delay(50);
   }

   else if(str=='6')
   {
   TV=0;
       Serialprintln(" TV OFF");
       delay(50);
   }
   str=0;
}
}

Riyaz Basha's Blog DBRT(2016/17)

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Bluetooth controller automation system using 8051