#include <io.h>
#include <mega8.h>
#include <math.h>
#include <delay.h>

#define btn_start PINC.1
#define btn_inc PINC.2
#define btn_dec PINC.3
#define btn_res PINC.0

void start_stop();
void display_7seg();

volatile unsigned int time_sec = 0;
_Bool run = 0;

void main(void)
{
PORTC = 0xEF;
TCCR2|=(1<<CS20)|(1<<CS21)|(1<<WGM21)|(0<<COM21)| (0<<COM20); //предделитель на 32+режим сравнения
OCR2 = 0xFA; //сравниваемое число (250)
TIMSK |= ( 1<<OCIE2 ); //разрешаем прерывания по сравнению
DDRC = 0xF0;
DDRB = 0xff;
DDRD = 0xff;

while(1)
{
	 if ( ~btn_start )
		 {
		 start_stop();
		 delay_ms(400);
		 }
		
	 if ( ~btn_inc )
	 {
		 if ( time_sec < 5940 )
			 time_sec+= 60;
		 delay_ms(400);
	 }
	
	 if ( ~btn_dec )
	 {
	 if ( time_sec >= 60 )
			 time_sec-=60;
		 delay_ms(400);
	 }
	
	 if ( ~btn_res )
	 {
		 time_sec = 0;
		 run = 0;
		 delay_ms(400);
	 }
display_7seg();
}
}

void start_stop( void )
{	
if ( run == 0 )
{
	 TCNT2 = 0x0; //обнуляем таймер
	 #asm("sei");
	 run = 1;
}
else
{
	 run = 0;
	 #asm("cli");
};
}

void display_7seg( void )
{
unsigned char bcd,low,high;
bcd = ceil(time_sec/60);
low = bcd % 10;
high = bcd/10;
		 /*switch (high)
		 {
			 case 0: { PORTB = 0b10110001; PORTD = 0b11100111; break;}
			 case 1: { PORTB = 0b11110111; PORTD = 0b11110111; break;}
			 case 2: { PORTB = 0b01111001; PORTD = 0b11100111; break;}
			 case 3: { PORTB = 0b01110011; PORTD = 0b11100111; break;}
			 case 4: { PORTB = 0b00110111; PORTD = 0b11110111; break;}
			 case 5: { PORTB = 0b00110011; PORTD = 0b11101111; break;}
			 case 6: { PORTB = 0b00110001; PORTD = 0b11101111; break;}
			 case 7: { PORTB = 0b11110111; PORTD = 0b11100111; break;}
			 case 8: { PORTB = 0b00110001; PORTD = 0b11100111; break;}
			 case 9: { PORTB = 0b00110011; PORTD = 0b11100111; break;}
		 }*/
		 switch(low)
		 {
			 case 0: { PORTB = 0b11011110; PORTD = 0b10111000; break;}
			 case 1: { PORTB = 0b11111111; PORTD = 0b10111110; break;}
			 case 2: { PORTB = 0b11011110; PORTD = 0b01111100; break;}
			 case 3: { PORTB = 0b11111110; PORTD = 0b00111100; break;}
			 case 4: { PORTB = 0b11111111; PORTD = 0b00111010; break;}
			 case 5: { PORTB = 0b11111110; PORTD = 0b00111001; break;}
			 case 6: { PORTB = 0b11011110; PORTD = 0b00111001; break;}
			 case 7: { PORTB = 0b11111111; PORTD = 0b10111100; break;}
			 case 8: { PORTB = 0b11011110; PORTD = 0b00111000; break;}
			 case 9: { PORTB = 0b11111110; PORTD = 0b00111000; break;}
		 }
}

interrupt [TIM1_COMPA] void timer1_compa_isr(void)
{
  unsigned char i =0;
  if(run == 1)
  {
	time_sec--;
  }
  if( time_sec == 0)
  {
	run = 0;
	#asm("cli");
	PORTC.4 = 1;
	for( i = 0; 8; i++)
	{
		PORTD = 0xFF; PORTC = 0xFF;
		delay_ms(700);
		PORTD = 0x0; PORTC = 0x0;
	}
  }
}