單片機--掉電保護24C02(c51)

#include"reg52.h"

#define uchar unsigned char

#define uintunsigned int

sbitsda=P3^4;

sbitscl=P3^6;

void delay_ee()//1us左右

{

;;

}

void start_ee()//開(kāi)始信號在scl為高電平器件，sda產(chǎn)生一個(gè)下降沿

{

sda=1;

delay_ee();

scl=1;

delay_ee();

sda=0;

delay_ee();

}

void stop_ee()//停止信號在scl為高電平器件，sda產(chǎn)生一個(gè)上升沿

{

sda=0;

delay_ee();

scl=1;

delay_ee();

sda=1;

delay_ee();

}

void respons_ee()//應答信號時(shí)鐘信號是高電平，如果sda被拉低，或者等到一定的時(shí)間，認定產(chǎn)生了應答

{

uchar i;

scl=1;

delay_ee();

while((sda==1)&&(i<20)) i++;

//while(sda==1)

scl=0;

delay_ee();

}

void init_ee()//初始化兩條線(xiàn)

{

sda=1;

delay_ee();

scl=1;

delay_ee();

//ce=0;

}

void write_byte_ee(uchar date)//寫(xiě)一個(gè)字節的數據

{

uchari,temp;

temp=date;

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

{

temp=(temp<<1);

scl=0;

delay_ee();

sda=CY;

delay_ee();

scl=1;

delay_ee();

}

scl=0;//scl一定要是低電平，才允許改變sda的狀態(tài)

delay_ee();

sda=1;//釋放sda數據線(xiàn)

delay_ee();

}

uchar read_byte_ee() //讀一個(gè)字節的數據

{

uchar i,j,k;

scl=0;

delay_ee();

sda=1;

delay_ee();

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

{

scl=1;

delay_ee();

j=sda;

k=(k<<1)|j;

scl=0;

delay_ee();

}

returnk;

}

void write_add_ee(uchar address,uchar date)

{

start_ee();

write_byte_ee(0xa0);//器件的地址，最后一位是0,表示寫(xiě)

respons_ee();

write_byte_ee(address);

respons_ee();

write_byte_ee(date);

respons_ee();

stop_ee();

}

ucharread_add_ee(uchar address) //讀EEPROM里面某個(gè)地址里面的值

{

uchar date;

start_ee();

write_byte_ee(0xa0);

respons_ee();

write_byte_ee(address);

respons_ee();

start_ee();

write_byte_ee(0xa1);

respons_ee();

date=read_byte_ee();

stop_ee();

return date;

}