【单片机期中测试】10.利用定时器实现pwm呼吸灯

#include<reg52.h>
#define uc unsigned char
sbit led=P2^0;
sbit key=P3^1;
unsigned int time=0,s=0;
void delay(uc c)
{
  uc a,b;
  for(;c>0;c--)
    for(a=38;a>0;a--)
      for(b=130;b>0;b--);
}
void ss() interrupt 3
{
  TH1=64536/256;
  TL1=64536%256;
  time++;
  if(time>=10) time=0;
  if(time<s)
    led=0;
  else
    led=1;
  TF1=0;
}
void main()
{
  TMOD=0x10;
  TH1=64536/256;
  TL1=64536%256;
  ET1=1;
  TR1=1;
  EA=1;
  while(1)
  {
    if(key==0) s++;
    if(s>=10) s=1;
    delay(1);
    while(key==0);
    delay(1);
  }
}