2-2.c

单片机产生20ms方波

#include<reg51.h>
sbit LED=P1^7;
main()
{
 TMOD=0X01;
 TH0=0x0d8;
 TL0=0x0f0;
 EA=1;
 ET0=1;
 TR0=1;
 while(1);
}
void timer0() interrupt 1
{
 TH0=0x0d8;
 TL0=0x0f0;
 LED=!LED;
}