求51单片机C语言编程

不能直接定时400ms，可定时50ms，采用中断方式，中断8次就是400ms。先计算出定时初始值，X=65536-50000=3CB0H。程序如下
#include<reg51.h>
sbit led=P2^0; //LED灯在P2.0上,0点亮
unsigned char t1n;//对定时50ms中断计数8次为400ms
void main()
{
TMOD=0x10;
TH1 =0x3C;//晶振频率=12M,定时50ms
TL1 =0xB0;
EA =1;//开中断
ET1 =1;
TR1 =1;
led =0;
while(1);
}
void T1_time() interrupt 3
{
TH1 =0x3C;
TL1 =0xB0;
t1n++;
if(t1n>=8)
{
t1n=0;
led=!led;//状态翻转
}
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