Atmega128을 이용한 0.5초 간격으로 : 깜빡이기

#include <mega128.h>
#include <delay.h>

#define LCD_RS   PORTA.0
#define LCD_RW   PORTA.1
#define LCD_EN   PORTA.2
#define LCD_Data    PORTA 
int count_2msec = 0;
unsigned char msec = 0;
unsigned char sec = 50;
unsigned char minute = 59;
unsigned char hour = 23;

void LCD_E(void)

{
    LCD_EN = 1;
    delay_us(250);
    LCD_EN = 0;    
}
void LCD_Command(unsigned char rs, unsigned char rw, unsigned char data)
{
    LCD_RS = rs;
    LCD_RW = rw;
    LCD_Data = ((LCD_Data & 0x0f) | (data & 0xf0));
    LCD_E();
    LCD_Data = ((LCD_Data & 0x0f) | ((data<<4) & 0xf0));
    LCD_E(); 
    delay_ms(2);
} 



void LCD_Init(void)

{
    delay_ms(30);
    LCD_Command(0,0,0x20);
    delay_ms(10);
    LCD_Command(0,0,0x20);
    delay_us(200);
    LCD_Command(0,0,0x20);
    LCD_Command(0,0,0x20);
    LCD_Command(0,0,0x28);
    LCD_Command(0,0,0x0C);
    LCD_Command(0,0,0x01);
    LCD_Command(0,0,0x06);
} 

void LCD_Position(unsigned char x,unsigned char y)

{
    if(y==0) LCD_Command(0,0,0x80+x);
    else LCD_Command(0,0,0xC0+x); 
}
void LCD_string(char x, char y, char flash *str)
{
    LCD_Position(x,y);
    while(*str) LCD_Command(1,0,*str++);
}
void main(void)
{
    DDRC = 0xff;
    PORTC = 0xff;
    DDRA = 0xff; 
    LCD_Init(); 
    TIMSK = 0x05;  // timer_counter_0, 1   mask
    TCCR0 = 0x05;  //  128 분주, 0.008msec
    TCNT0 = 6;     // 250 개
    TCCR1B = 0x05;  // 1024 분주
    TCNT1H = 0xE1;
    TCNT1L = 0x7C;
    LCD_string(0,0,"   = CLOCK! =   ");
    LCD_string(0,1,"xx] xx:xx:xx:xx ");
    #asm("sei")    
    while (1){
        LCD_Position(0,1);
        if( hour >= 12 )LCD_Command(1,0,'P');
        else LCD_Command(1,0,'A');        
        LCD_Position(1,1);
        LCD_Command(1,0,'M'); 
        LCD_Position(4,1);
        LCD_Command(1,0,(hour/10)+0x30);      
        LCD_Command(1,0,(hour%10)+0x30);
        LCD_Position(7,1);
        LCD_Command(1,0,(minute/10)+0x30);      
        LCD_Command(1,0,(minute%10)+0x30);
        LCD_Position(10,1);
        LCD_Command(1,0,(sec/10)+0x30);      
        LCD_Command(1,0,(sec%10)+0x30);
        LCD_Position(13,1);
        LCD_Command(1,0,(msec/10)+0x30);      
        LCD_Command(1,0,(msec%10)+0x30);
        if( count_2msec < 250 ){
            LCD_Position(6,1);   LCD_Command(1,0,':');
            LCD_Position(9,1);   LCD_Command(1,0,':');
            LCD_Position(12,1);   LCD_Command(1,0,':');
            }
        else {
            LCD_Position(6,1);   LCD_Command(1,0,' ');
            LCD_Position(9,1);   LCD_Command(1,0,' ');
            LCD_Position(12,1);   LCD_Command(1,0,' ');
            }    
        }
}


interrupt [TIM0_OVF] void timer_0 (void)
{
    TCNT0 = 6;
    count_2msec++;
    msec=count_2msec*5;
    if( count_2msec >= 500 ) {
        count_2msec = 0;
        sec++;
        PORTC.0 = ~PORTC.0;
    }
    if( sec >= 60 ){
        sec = 0;
        minute++;
        }
    if( minute >= 60 ){
        minute = 0;
        hour++;
    }
    if( hour >= 24 ) hour = 0;
}
interrupt [TIM1_OVF] void timer_1 (void)
{
    TCNT1H = 0xE1;
    TCNT1L = 0x7C;  
    PORTC.7 = ~PORTC.7;
}