#include <mega8.h>
#include <delay.h>
unsigned char key=0,key1=0,key2=0;
interrupt [EXT_INT1] void ext_int1_isr(void)
{
unsigned char reg;
reg=SREG;
if(PINB.0==0)key2=0;
if(PINB.1==0)key2=4;
if(PINB.2==0)key2=8;
if(PINB.3==0)key2=12;
DDRB=0x0f;
PORTB=0xf0;
delay_us(2);
if(PINB.7==0)key1=0;
if(PINB.6==0)key1=1;
if(PINB.5==0)key1=2;
if(PINB.4==0)key1=3;
key=key2+key1;
DDRB=0xf0;
PORTB=0x0f;
SREG=reg;
GICR|=0x80;
}
void main(void)
{
PORTC=0x00;
DDRC=0xff;
PORTD=0x00;
DDRD=0x00;
GICR|=0x80;
MCUCR=0x00;
GIFR=0x80;
while (1)
{
#asm("cli")
DDRB=0xf0;
PORTB=0x0f;
#asm("sei")
PORTC=key;
GICR|=0x80;
};
}
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