11.c

单片机定时器的应用

//采用10MHZ晶振，在p1.0上输出周期为2.5s，占空比为20%的脉冲信号

#include<reg51.h>
sbit P1_0=P1^0;
#define uchar unsigned char
 uchar time;
 uchar period=250;
 uchar high=50;
 time0() interrupt 1 using 1
{TH0=-8333/256;
TL0=-8333%256;
if(++time==high)P1=0;
else if(time==period)
  {time=0;
  P1=1;}
}
 main()
{TMOD=0x01;
P1_0=0;
TH0=-(8333/256);
TL0=-(8333%256);
EA=1;
ET0=1;
TR0=1;
do{}while(1);
}