ngắt ngoài

#include<htc.h>
__CONFIG(XT & WDTDIS & PWRTEN & MCLREN & UNPROTECT & SWBOREN & IESODIS & FCMDIS & LVPDIS & DEBUGDIS);
__CONFIG(BORV21);
#define _XTAL_FREQ 4000000
//================================================================
//chuong trinh ung dung ngat ngoai
//cong tac nhan noi chan RA4,khong nhan = 1,nhan =0
//moi lan nhan 1 led se sang
//khi nhan du 8 led sang thi se tat dan tung led,tat het thi se sang lai
//board led la cua chi phuong dua (port ra muc 0 thi led sang)


signed char i,k;

void main(void)
{

// Khoi tao I/O cho cac port
ANSEL=0x00;
ANSELH=0x00;

TRISD = 0x00; //port d as output
GIE=1;
INTE=1;
INTEDG=0;//CANH XUONG
INTF=0;


PORTD=0xFF;
i=0;
k=0;
while(1);

};
void interrupt isr()
{
//__delay_ms(30);
if (RB0==1)//phim duoc nha
{ if (k%2==0)
{PORTD -=1<<i;
i++;
}
else{PORTD +=1<<i;i++;};

if (i>7) {i=0;k++;};



};
INTF=0;
}