#include<reg52.h>
int a = 0xf0;
unsigned char cnt;
sbit p1_0 = P1^0;
void main()
{
//IT0 = 1; //TCON寄存器的第0位,頭文件已定義sbit IT0 = TCON^0;
EA = 1; //EA = IE^7;
ET1 = 1;
TMOD = 0x10; //00110000 定時(shí)器1工作方式1，16位計數
//EX0 = 1;
TH1 = (65536 - 50000) / 256;
TL1 = (65536 - 50000) % 256;
TR1 = 1;
cnt = 0;
while(1)
{
if(cnt == 20)
{
p1_0 = ~p1_0;
cnt = 0;
}
}
}
void ext0() interrupt 3 //[using n],使用第幾組寄存器.沒(méi)加using的話(huà)，自動(dòng)分配寄存器.
{
TH1 = (65536 - 50000) / 256;
TL1 = (65536 - 50000) % 256;
cnt++;
}
