IR Based Home Automation

We are operating the home appliances by using an IR remote which is interfaced with the microcontroller by using various components.

            A 12v power supply is generated and it is supplied to the micro controller by using a transformer. Atmel microcontroller based hardware is used along with real time clock interface. The development involves writing the software code for microcontroller at which the automation can be done. The microcontroller based hardware is chosen to implement this concept. The loads like lights, motors, heaters, power controlling system and also current through the loads can be controlled in this project. We can control all loads at a time from one place (control room) without connecting any physical wire between loads and control room.

Since AC loads are also controlled in this project and the microcontroller cannot handle AC loads, TRIAC is used to control the AC loads. The speed of AC motor can be varied rapidly on and off by TRIAC. The main advantage of using a TRIAC to vary the speed of an AC motor is the TRIAC reduces the energy flow to the motor and TRIAC works very well for alternating currents. Hence, in our module we use the TSOP 1738 IR receiver, MOC 3021 TRIAC, IR remote controller, crystal oscillator and some other related equipment. Crystal oscillator is used to generate a frequency of 11.0592MHz. Two load capacitors of 33 pF are used to eliminate the noise which is occurred in the oscillator. For reset button we used one pull up switch which is connected to reset pin of micro controller. An IR remote control device uses IR light which is invisible light about 950nm wavelength. One biggest problem in using IR light is that there many other sources of it like sun, light bulbs, fire. In order to exclude other sources, IR signal is modulated by some frequency. Receiver has to be tuned for this frequency. Mostly remote controls transmit IR signal using 36 kHz frequency signals. Here in our module we are using TSOP1738 IR receiver which generates the frequency of 38 kHz, exactly matched with our remote controller.

            Thus, we can control (i.e., switch on/off) the home appliances by using an IR remote which is interfaced with microcontroller.

CODE:

#include <REG8051.H> sbit load1 = P1^7; sbit load2 = P1^6; sbit load3 = P1^5; sbit load4 = P1^4; sbit load5 = P1^2; sbit fan = P3^7; sbit ir=P3^2; sbit led=P3^4; bit cc1,cc,a,fanon,l1,l2,l3,l4,l5,l6,power; unsigned char speed,ledblink=0; unsigned char key,key1,count=1; void irs(void) interrupt 0 using 0 { EX0=0; TL0=0x29; TH0=0XFa; count=1; ET0=1; TR0=1; } void time(void) interrupt 1 using 1 { TR0=0; count=count+1; if(count==3) //check bit cc=ir; if(cc1!=cc) { if((count>8)&&(count<15)) { a=ir; key=key<<1; key=key|a; } if(count==14) { key1=key; cc1=cc; key=0xff; } } if(count<65) { if(ledblink==1) led=~led; TL0=0x29; TH0=0XFa; TR0=1; } else { ET0=0; led=0; EX0=1; ledblink=0; } } void pulse (void) interrupt 2 using 2 { EX1=0; fan=1; switch(speed) { case 9: TL1=0Xb6; TH1=0XF8; break; case 8: TL1=0Xb6; TH1=0XF3; break; case 7: TL1=0X55; TH1=0XF1; break; case 6: TL1=0Xb6; TH1=0XF0; break; case 5: TL1=0X55; TH1=0Xf0; break; case 4: TL1=0Xdd; TH1=0XEf; break; case 3: TL1=0X22; TH1=0XEf; break; case 2: TL1=0Xa0; TH1=0XEe; break; case 1: TL1=0X7d; TH1=0XEe; break; } TR1=1; } void time2(void) interrupt 3 using 3 { TR1=0; fan=0; EX1=1 } void main(void ) { fanon=0 l1=l2=l3=l4=l5=l6=1; power=0; fan=1; led=0; speed=1; key1=0xff; key=0xff; TMOD=0X11; EA=1; EX0=1; PX0=1; while(1) { if(key1==0xc1) //1 { ledblink=1; l1=~l1; load1=l1; key1=0xff; } if(key1==0xc2) //2 { ledblink=1; l2=~l2; load2=l2; key1=0xff; } if(key1==0xc3) //3 { ledblink=1; l3=~l3; load3=l3; key1=0xff; } if(key1==0xc4) //4 { ledblink=1; l4=~l4; load4=l4; key1=0xff; } if(key1==0xc6) //6 { ledblink=1; load5=l5; key1=0xff; } if(key1==0xc5) //5 { ledblink=1; fanon=~fanon; l6=fanon; if(fanon) { EX1=1; ET1=1; else { fan=1; EX1=0; ET1=0; } key1=0xff; } if(key1==0xe0) //up { if(speed<9) { speed=speed+1; ledblink=1; } else speed=9; key1=0xff; } if(key1==0xe1) //down { if(speed>1) { ledblink=1; speed=speed-1; } else speed=1; key1=0xff } if(key1==0xcc) //power { ledblink=1; power=~power; if(power) { EX1=0; ET1=0; load1=load2=load3=load4=load5=fan=1; fanon=0; } else { load1=l1; load2=l2; load3=l3; load4=l4; load5=l5; fanon=l6; if(fanon) { EX1=1; ET1=1; } } key1=0xff; } } }