//1、向24C02中写入当前的时间，下次开机就会从
上次断电时的时间开始计时

//2、重点掌握IIC总线几个常用信号的写法；
//

*/

#include
#define uint unsigned int
#define uchar unsigned char
sbit sda=P1^0;
sbit scl=P1^1;
uchar num1,num1,flag1,flag2,sec;
void delay();
void delayms(uint z);
void start();
void stop();
void sck();
void writebyte(uchar date);
uchar readbyte();
void writeaddr(uchar addr,uchar date);
uchar readaddr(uchar addr);
void intc();
void disp();
//=========================
void main()
{ uchar temp;
intc();
P0=temp;
sec=readaddr(2);
if(sec>100)
sec=0;
while(1)
{
if(flag1==1)
{flag1=0;
writeaddr(2,sec);
}
disp();

}
}
//-----初始化------
void intc()
{
scl=1;
delay();
sda=1;
delay();
TMOD=0x01;
TH0=(65536-10000)/256;
TL0=(65536-10000)%256;
EA=1;
ET0=1;
TR0=1;
}
//----------------
void delay()
{;;}
//-----------------
void delayms(uint z)
{
uint x,y;
for(x=0;x for(y=0;y<112;y++);

}
//-------24C04启动信号---------

void start()
{
sda=1;
delay();
scl=1;
delay();
sda=0;
delay();
}
//--------24C04停止信号--------
void stop()
{
sda=0;
delay();
scl=1;
delay();
sda=1;
delay();

}

//-------24C04应答信号-------
void sck()
{ uchar i=0;
scl=1;
delay();
while(sda==1&&i<255)
i++;
scl=0;
delay();
}
//-------24C04写一个字节------
void writebyte(uchar date)
{
uchar i;
for(i=0;i<8;i++)
{
date=date<<1;
scl=0;
delay();
sda=CY;
delay();
scl=1;
delay();
}
scl=0;//写完一个字节后再把总线拉成接收状态；
delay();
sda=1;
delay();
}

//---------24C04读一个字节---------

uchar readbyte()
{
uchar i,k;
scl=0;//写完一个字节后再把总线拉成接收状态；
delay();
sda=1;
delay();
for(i=0;i<8;i++)
{
scl=1;
delay();
k=(k<<1)||sda;
delay();
scl=0;
delay();
}
delay();
return k;
}

//-------24C04指定地址写一个字节------
void writeaddr(uchar addr,uchar date)
{
star();
writebyte(0xa0);
ack();
writebyte(addr);
ack();
writebyte(date);
ack();
stop();
}

//--------24C04指定地址读一个字节--------
uchar readaddr(uchar addr)
{uchar date1;
star();
writebyte(0xa0);
ack();
writebyte(addr);
ack();
writebyte(0xa1);
ack();
date1=readbyte();
stop();
return date1;
}

//===================
void disp()
{
P0=sec/10;
P2=0xfe;
delayms(5);
P0=0;
delayms(1);
P0=sec%10;
P2=0xfd;
delayms(5);
P0=0;
delayms(1);
}

//----------------
void timer0() interrupt 1
{
TH0=(65536-10000)/256;
TL0=(65536-10000)%256;
num1++;
if(num1==100)
{num1=0;flag1=1;sec++;
if(sec>99)
sec=0;
}

}