51单片机控制继电器的程序看不太懂，希望大神在每句后面注解一下。

#include #include #define uint unsigned int sbit a=P1^4;// sbit b=P2^3;// sbit c=P2^5;// sbit d=P2^7;// uint t; void Init_t0(void) //定时器初始化 { TMOD=0x01; TH0=0x4C;TL0=0x00; //50ms ET0=1; TR0=1; ... #include
#include
#define uint unsigned int
sbit a=P1^4;//
sbit b=P2^3;//
sbit c=P2^5;//
sbit d=P2^7;//
uint t;
void Init_t0(void) //定时器初始化
{
TMOD=0x01;
TH0=0x4C;TL0=0x00; //50ms
ET0=1;
TR0=1;
}
void time0_server_(void)interrupt 1
{
TH0=0x4C;TL0=0x00;
t++;
}
void main()
{
Init_t0();
a=0;//
b=0;//
c=0;//
d=0;//
t = 0;
EA = 1;
while(1) //循环
{
switch(t)
{
case 0:
a = 1;
b = c = d = 0;
break;
case 40:
b = 1;
a = c = d = 0;
break;
case 80:
c = 1;
a = b = d = 0;
break;
case 120:
d = 1;
a = b = c = 0;
break;
case 160:
t=0;
break;
default:
break;

}
}
}