单片机 led灯以1赫兹，2赫兹，3赫兹。4赫兹闪烁的程序

Answer 1

#include<reg51.h>
#define uchar unsigned char
uchar times;
uchar val;
sbit led=P1^0;
sbit key=P1^4;
void t0isr() interrupt 1
{
TH0=(65536-25000)/256;
TL0=(65536-25000)%256;
times++;
if(times>=val*5)
{
times=0;
led=~led;
}
}
main()
{
TMOD=0x01;
TH0=(65536-25000)/256;
TL0=(65536-25000)%256;
TR0=1;
ET0=1;
EA=1;
val=4;
while(1)
{
if(key==0)
{
while(key==0);
val%=4;
val++;
}
}
}