AT24C02EEPROM芯片《實(shí)現(xiàn)對(duì)其讀和寫》

unsigned char readbyte() //讀一個(gè)字節(jié)

{

unsigned char i,j,k=0;

scl=0; nop(); sda=1;

for (i=0;i<8;i++)

{

nop(); scl=1; nop();

if(sda==1)

j=1;

else

j=0;

k=(k<<1)|j;

scl=0;

}

nop();

return(k);

}

void clock() //I2C總線時(shí)鐘

{

unsigned char i=0;

scl=1;

nop();

while((sda==1)&&(i<255))

i++;

scl=0;

nop();

}

////////從24c02的地址address中讀取一個(gè)字節(jié)數(shù)據(jù)/////

unsigned char read24c02(unsigned char address)

{

unsigned char i;

start();

writebyte(0xa0);

clock();

writebyte(address);

clock();

start();

writebyte(0xa1);

clock();

i=readbyte();

stop();

delay1(10);

return(i);

}

//////向24c02的address地址中寫入一字節(jié)數(shù)據(jù)info/////

void write24c02(unsigned char address,unsigned char info)

{

EA=0;

start();

writebyte(0xa0);

clock();

writebyte(address);

clock();

writebyte(info);

clock();

stop();

EA=1;

delay1(50);

}

void main()

{

unsigned char i;

TMOD=0x01; //定時(shí)器工作在方式1

ET0=1;

EA=1;

TH0=0x4c; //對(duì)TH0 TL0賦值

TL0=0x00; //使定時(shí)器0.05秒中斷一次

TR0=1; //開始計(jì)時(shí)

init(); //初始化24C02

sec=read24c02(1);//每次重新開機(jī)時(shí)，讀出保存的數(shù)據(jù)賦于sec

while(1)

{

i=20;

//num=read24c02(1);//讀出保存的數(shù)據(jù)賦于num

while(i--)

{

display(sec/10,sec%10);

}

if(write==1) //判斷計(jì)時(shí)器是否計(jì)時(shí)一秒

{

write=0; //清零

write24c02(1,sec); //在24c02的地址1中寫入數(shù)據(jù)sec

}

}

}

void timer0(void) interrupt 1 using 0 //定時(shí)中斷服務(wù)函數(shù)

{

TH0=0x4c; //對(duì)TH0 TL0賦值 ,每隔0.05s發(fā)出一次中斷。

TL0=0x00; //重裝計(jì)數(shù)初值

times++; //每過(guò)250ust tcnt加一

if(times==20) //計(jì)滿20次（1秒）時(shí)

{

times=0; //重新再計(jì)

sec++;

write=1; //1秒寫一次24C08

if(sec==60) //定時(shí)100秒，在從零開始計(jì)時(shí)

{sec=0;}

}

}