Плавное мигание светодиода

#include <tiny2313a.h>
#include <delay.h>
int i;
int a;
int b;
// Declare your global variables here

void main(void)
{
// Function: Bit7=In Bit6=In Bit5=In Bit4=In Bit3=In Bit2=In Bit1=In Bit0=Out
DDRB=(0<<DDB7) | (0<<DDB6) | (0<<DDB5) | (0<<DDB4) | (0<<DDB3) | (0<<DDB2) | (0<<DDB1) | (1<<DDB0);
// State: Bit7=T Bit6=T Bit5=T Bit4=T Bit3=T Bit2=T Bit1=T Bit0=0
PORTB=(0<<PORTB7) | (0<<PORTB6) | (0<<PORTB5) | (0<<PORTB4) | (0<<PORTB3) | (0<<PORTB2) | (0<<PORTB1) | (0<<PORTB0);

i=0;
a=0;

while(1){
b=202;

for (i=0;i<100;)
{
PORTB.0 =1;
delay_ms(a);
PORTB.0 = 0;
b=b-2;
delay_ms(b);
a=a+2;
i++;
};

PORTB.0=0;
i=0;
b=0;
a=100;
for (i=0;i<100;)
{
PORTB.0 =1;
delay_ms(a);
PORTB.0 = 0;
b=b+1;
delay_ms(b);
a=a-1;
i++;
};

PORTB.0=0;
i=0;
a=0;
delay_ms(100);
}
}