AC Lamp Dimmer Using TRIAC and PIC16F877A

#include <pic.h>                                              //triac light dimmer   
#define _XTAL_FREQ 20000000

#define TRIAC1 RB3        
#define UP  RB7 
#define DWN RB6 

#define MAX_TIME 3500
#define MIN_TIME 1

int k=0,dly=0;

void interrupt isr()
{
///////////////////////////////////// 
if(INTF)
{
INTF=0; 
while(!RB0); 
dly=k;
while(dly--); 
TRIAC1=1;
#asm
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop; 
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
#endasm
TRIAC1=0; 
}
}
/////////////// MAIN //////////////////////
void main()
{
 TRISD=0x0; TRISB=0xF1;
    
   k=300;
 INTE=1; INTEDG=1;    PEIE=1;GIE=1;

while(1)
{
if(!UP)
{
__delay_ms(100);  
if(!UP)
{
  if(k>=MAX_TIME) k=MAX_TIME; k++;  
 dly=k;
}   
} 
 else if(!DWN)
{
__delay_ms(100);
if(!DWN)
{
   if(k<=MIN_TIME) k=MIN_TIME; k--;   
 dly=k;
}
} 
 }
}
/////////////////////////////////////////////////

steps
1, read LDR value  using ADC
2, PID   [optional]   
3, set ADC data is dly value [see the program:    TRIAC Firing delay ] 
    ADC data should be scaled 

   #define MAX_TIME 3500
   #define MIN_TIME 1

4, in a brighter light environment LDR reading will be low [as per the LDR circuit ],smaller ADC value means   smaller delay  from zero crossing to TRIAC firing.

#include <mega8535.h> 
#include <delay.h>
bit ZC;

// External Interrupt 0 service routine
interrupt [EXT_INT0] void ext_int0_isr(void)

 {
    ZC=1;
 }

// Declare your global variables here

void main(void)
{
PORTA=0x00;
DDRA=0x00;

PORTB=0x00;
DDRB=0xFF;

PORTC=0x00;
DDRC=0xFF;
 
PORTD=0x00;
DDRD=0x00;

// External Interrupt(s) initialization
// INT0: On
// INT0 Mode: Falling Edge
// INT1: Off
// INT2: Off
GICR|=0x40;
MCUCR=0x02;
MCUCSR=0x00;
GIFR=0x40;
  
// Global enable interrupts
#asm("sei")

while (1)
      {
        if(ZC==1)
        {PORTB=0x00;
        delay_ms(5);  // firing triac 5 ms after zero cross detected to get 50% brightness
        PORTB=0x01;   
        delay_us(10);  // firing pulse width 10us
        PORTB=0x00;
        ZC=0;
        }  
      }
}

#include <pic.h>                                             //XMAS    STAR-    20 MHZ CLOCK
#define _XTAL_FREQ 20000000

#define TRIAC1 RD2     
#define MIN_TIME 1
#define MAX_TIME 4500
int k=1,dly=1;
/////////////// MAIN //////////////////////
void main()
{
int j=-10;
unsigned int cnt=0;
k=4500;	
TRISD=0xF0; TRISB=0xff;   TRIAC1=0;  
while(1)  
{
while(RB0);
{
if(k>4500){ j=-10;}   if(k<1){  j=30;}  k=k+j;  

dly=k; while(dly--);
TRIAC1=1;
while(!RB0); 
#asm
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop; 
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
nop;nop;nop;nop;nop;nop;
#endasm 
TRIAC1=0; 
}

}

}