Home Automation with GSM

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The system is implemented with ATMEL microcontroller based hardware unit. In current industry there exists lot of variants of 8 bit microcontrollers of MCS-51 family. We have chosen AT89S52microcontroller as the features include

-          8 Bit CPU for implementing the controller block

-          It has got 8 Kbytes of flash memory,  used  for storing the instructions 

-          It has got on chip UART module for communicating with GSM module using RS232 protocol.

-          It has got In system programming(ISP) feature

A 16X2 Liquid crystal character display(LCD) will be used for displaying the  data from the desired memory locations. The LCD is connected to PORT2 of the microcontroller.

A L293D voltage driver is interfaced to the microcontroller to drive the motor.

GSM is a digital mobile telephone system that is widely used because of its low power consumption and low cost feature. It is serially connected to the microcontroller via a line driver MAX232. GSM modem communicates using RS-232 protocol with the microcontroller. The RS-232 protocol is asynchronous serial communication protocol and works at the baud rate of 9600.

CODE

#include<reg51.h> #include "lcd.h" void transmit(unsigned char *); sbit light = P3^6; sbit fan = P2^6; unsigned char str[85]; unsigned char i,j,s; unsigned char c; void main(void) { TMOD = 0x20; SCON = 0x50; TH1 = 0xfd; TR1=1; light=0; fan=0; init_lcd(); delay_ms(1000); init_lcd(); display_lcd("UC BASED HOME"); cmd_lcd(0xc0); display_lcd("CONTROL (SMS)"); delay_ms(5000); init_lcd(); display_lcd("MODEM TEST? "); delay_ms(500); cmd_lcd(0xc0); delay_ms(1000); transmit("at"); SBUF=0x0d; while(!TI); TI=0; i=0; j=0; while(i<2) { while(!RI); RI=0; str[j]=SBUF; if(SBUF==0x0d) i++; j++; } str[j]='\0'; cmd_lcd(0xC0); display_lcd("MODEM OK"); delay_ms(2000); transmit("AT+CMGD=1,1"); SBUF=0x0d; while(!TI); TI=0; i=0; j=0; while(i<2) { while(!RI); RI=0; str[j]=SBUF; if(SBUF==0x0d) i++; j++; } str[j]='\0'; display_lcd("messgae deleted"); delay_ms(2000); /******** RECEIVING MESSAGES*********/ cmd_lcd(0x01); while(1) { transmit("AT+CMGL="); SBUF='"'; while(!TI); TI=0; transmit("REC UNREAD"); SBUF='"'; while(!TI); TI=0; SBUF=0x0d; while(!TI); TI=0; i=0; /* Gives the total characters received */ j=0; /* Gives total characters displayed on LCD */ s=0; /* Tells the START and END of decryption */ while(i<4) { while(!RI); RI=0; str[j]=SBUF; if(SBUF==0x0d) i++; j++; } cmd_lcd(0x01); str[j]='\0'; /*write_lcd(str[71]); write_lcd(str[72]); write_lcd(str[73]); write_lcd(str[73]); write_lcd(str[74]); write_lcd(str[75]); write_lcd(str[76]); write_lcd(str[77]);*/ write_lcd(str[78]); write_lcd(str[79]); write_lcd(str[80]); write_lcd(str[81]); write_lcd(str[82]); write_lcd(str[83]); delay_ms(2000); /*c=str[83]; cmd_lcd(0xc0); switch(c) { case '2': display_lcd("LIGHT ON"); light=1; delay_ms(1000); break; case '1': display_lcd("LIGHT OFF"); light=0; delay_ms(1000); break; case '4': display_lcd("FAN ON"); fan=1; delay_ms(1000); break; case '3': display_lcd("FAN OFF"); fan=0; delay_ms(1000); break; case 'A': display_lcd("LIGHT&FAN ON"); light=1; fan=1; delay_ms(1000); break; case '0': display_lcd("LIGHT&FAN OFF"); light=0; fan=0; delay_ms(1000); break; }*/ //str[83]=0; } } /********** TRANSMIT COMMAND TO MODEM **********/ void transmit(unsigned char *t_data) { while(*t_data!='\0') { SBUF = *t_data; while(!TI); TI=0; t_data++; } }