DTMF Controlled Home Automation System Using 8951

This project based on DTMF (Dual Tone multi frequency) which is generated in cellular phones. Here, by using a cell phone we controls the home appliances from anywhere in the world (In Network Area). Below you can see the diagram of DTMF keypad. When we press any key then it generates a frequency after mixing two frequencies. And then send it to the receiver end over communication channel.

Fig.1: Image of DTMF Keypad with alloted frequencies

User can activate their devices using this DTMF keypad as he/she want to activate. The encoder encodes the user input and sends via a communication channel. The receiver receives the modulated signal and demodulates it and the user input. In this system, we are going to make a DTMF based home/office appliance. Block diagram of this system given below-

Fig. 2: Block Diagram of 8051 Microcontroller based Home Automation System

Fig. 3: Block Diagram of DTMF based Home Automation System

This system is designed for controlling the devices, it includes a cell phone which is connect to the system via head set. To active the cellular phone part of the system a call is to be made and as the call is answered, in response the user would enter a three/four(as he/she want) digit password to access the system to control devices. As the caller press the specific password, it results in turning ON or OFF specific device. The device switching is achieved by Relays.

Image Showing Appliances Controlled by a Mobile Phone on DTMF based Home Automation System

Fig. 4: Image of DTMF and 8051 Microcontroller based Home Automation System

Circuit Designing

Circuit:

In this system we made circuit in three main parts one is DTMF decoder secondly transmitter which accepts the output of decoder and third one is receiver which accepts the input of transmitter and the we connects our controlling devices like TV, Fan, AC, Mixer, Bulb etc as we want to controls. In this circuit we used serial communication between 8951 microcontrollers for transferring the encoded from transmitter to receiver. This means in circuit one second part of circuit made serial transmitter which send encoded data serially and the third part of circuit made serial receive which receives the serially transmitted data serially. Some password already defined in the third part of circuit. When receiver receives any input from transmitter then it compares the input data with stored or defined data. If any match found then it activates related or particular device we can see the particular operation In the 16×2 LCD. In this circuit I used led’s in place of home appliance. In the code we stored data of length 4.

Eg.

· 4201 for on first relay or device.

· 4202 for on second relay or device.

· 4211 for off first relay or device.

· 4212 for off second device.

· 4205 for on all devices.

· 4215 for off all devices

Cirucit Images

Fig. 5: Image showing appliances controlled by a mobile phone on DTMF based Home Automation System

Fig. 6: Prototype of 8051 Microcontroller based device for Smart Home

Fig. 7: Prototype of 8051 Microcontroller and DTMF based Home Automation System

Fig. 8: Image showing Home Automation Board integrated with house appliances

PCB Images

PCB Images

Fig. 9: Image of PCB used in DTMF based Home Automation System

Fig. 9: Image of PCBs used in DTMF based Home Automation System

Fig. 10: Image of PCB used in DTMF based Home Automation System

Fig. 11: Image of PCB used in DTMF based Home Automation System with holes drilled for components

Project Source Code

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****************************DTMF RECEIVER************************* #include<reg51.h>
#include<string.h>
#define all_on P2=0xf0			  
#define all_off P2=0x00
#define dataport P0
#define cmdport P1
#define output P2
char y;int k;
sbit rs=cmdport^0;
sbit rw=cmdport^1;
sbit en=cmdport^2;
sbit tv=output^0;
sbit fan=output^1;
sbit light=output^2;
sbit ac=output^3;
char compare1[4]="4211"; // TV ON
char compare2[4]="4212"; // FAN ON
char compare3[4]="4214"; // LIGHT ON
char compare4[4]="4204"; // AC ON
char compare5[4]="4210"; // TV OFF
char compare6[4]="4212"; // FAN OFF
char compare7[4]="4213"; // LIGHT OFF
char compare8[4]="4214"; // AC OFF
char compare9[4]="4205"; // ALL ON
char compare0[4]="4215"; // ALL OFF
char input[4]; //input string
void delay(int time)
{
unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<1275;j++);
} // delay funtion
void lcddata(char item)
{
dataport=item;
rs=1,rw=0,en=1;
delay(5),en=0;
} // funtion to send data to lcd
void print(char cmd, char *str)
{
dataport=cmd;
rs=0,rw=0,en=1;
delay(5),en=0; // funtion to send cmd and print data to lcd
while(*str!='')
{
lcddata(*str);
str++;
}
}
void LCD_clear()
{
delay(50);
print(0x01,0);
}
// funtion to clear lcd
void LCD_Init() // funtion to LCD initialize
{
print(0x38,0);
print(0x06,0);
print(0x0e,0); // print introduction on lcd
print(0x80," A PROJECT BY ");
print(0xc0," SADDAM KHAN ");
LCD_clear();
print(0x80,"DTMF CONTROLLED ");
print(0xc0,"HOME AUTOMATION ");
LCD_clear();
print(0x80," SYSTEM READY ");
}
void serial_init()
{
TMOD=0X20;
SCON=0X50;
TH1=0XFD;
TR1=1;
} // funtion to initialize serial communication

void main() // main program
{
all_off;
serial_init();
LCD_Init(); // initiaze lcd and serial communication
while(1)
{
print(0xC0,"ENTER CODE "); // enter a string of length 4 by using for loop
for(k=0;k<4;k++)
{
while(RI==0);
y=SBUF;
input[k]=y;
lcddata(input[k]);
RI=0;
delay(40);
}


if(strcmp(compare1, input)==0) // compare input strings with stored strings
{LCD_clear();print(0x80," TV ON ");tv=1;}
if(strcmp(compare2, input)==0)
{LCD_clear();print(0x80," FAN ON ");fan=1;}
if(strcmp(compare3, input)==0)
{LCD_clear();print(0x80," LIGHT ON ");light=1;}
if(strcmp(compare4, input)==0)
{LCD_clear();print(0x80," AC ON ");ac=1;}
if(strcmp(compare5, input)==0)
{LCD_clear();print(0x80," TV OFF ");tv=0;}
if(strcmp(compare6, input)==0)
{LCD_clear();print(0x80," FAN OFF ");fan=0;}
if(strcmp(compare7, input)==0)
{LCD_clear();print(0x80," LIGHT OFF ");light=0;}
if(strcmp(compare8, input)==0)
{LCD_clear();print(0x80," AC OFF ");ac=0;}
if(strcmp(compare9, input)==0)
{LCD_clear();print(0x80," ALL ON ");all_on;}
if(strcmp(compare0, input)==0)
{LCD_clear();print(0x80," ALL OFF ");all_off;}}
}
******************DTMF TRANSMITTER******************
#include<reg51.h>
sbit led=P2^0;char k;
void delay(int time)
{unsigned int i,j;
for(i=0;i<time;i++)
for(j=0;j<1000;j++);}
void serial_init()
{TMOD=0X20;
SCON=0X50;
TH1=0XFD;
TR1=1;}
void transmit(char k)
{SBUF=k;
while(TI==0);
TI=0;}
void main()
{
P1=0xff;
serial_init();
delay(500);
while(1)
{P1=0xff;
if(P1==0xf1){transmit('1');while(P1==0xf1);delay(20);}
if(P1==0xf2){transmit('2');while(P1==0xf2);delay(20);}
if(P1==0xf3){transmit('3');while(P1==0xf3);delay(20);}
if(P1==0xf4){transmit('4');while(P1==0xf4);delay(20);}
if(P1==0xf5){transmit('5');while(P1==0xf5);delay(20);}
if(P1==0xfa){transmit('0');while(P1==0xfa);delay(20);}
}
}
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