实现AT24C02的数据读写操作

/***************************************************************
功能:11:32 2008-6-27
作者:SG
时间:2004-03-15
版本:V1.0
***************************************************************/

#include "INTRINS.H"
#include "reg52.h"

#define  WriteDeviceAddress 0xa0 //写驱动地址指令
#define  ReadDeviceAddress 0xa1  //读驱动地址指令

sbit AT24C02_SCL = 0xa4;
sbit AT24C02_SDA = 0xa5;

/*-------------------------------------------------------------
功能：发起始信号
------------------------------------------------------------*/
void Start_Cond()
{
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 1;
    _nop_();
    AT24C02_SCL = 1;
    _nop_();
    AT24C02_SDA = 0;
    _nop_();
}

/*-------------------------------------------------------------
功能：发停止信号
------------------------------------------------------------*/
void Stop_Cond()
{
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 0;
    _nop_();
    AT24C02_SCL = 1;
    _nop_();
    AT24C02_SDA = 1;
    _nop_();
}

/*-------------------------------------------------------------
功能：发确认信号
------------------------------------------------------------*/
void Ack()
{
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 0;
    AT24C02_SCL = 1;
    _nop_();
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 1;
}

/*-------------------------------------------------------------
功能：发无确认信号
------------------------------------------------------------*/
void NoAck()
{
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 1;
    _nop_();
    AT24C02_SCL = 1;
    _nop_();
    AT24C02_SCL = 0;
    _nop_();
}

/*-------------------------------------------------------------
功能：写一个字节数据
------------------------------------------------------------*/
bit Write8Bit(unsigned char input)
{
    unsigned char i;
    for (i=0;i<8;i++)
    { 
        AT24C02_SCL = 0;
        input <<= 1;
        AT24C02_SDA = CY;
        AT24C02_SCL = 1;
        
    }
    AT24C02_SCL = 0;
    _nop_();
    AT24C02_SDA = 1;
    AT24C02_SCL = 1;
    _nop_();
    CY = AT24C02_SDA;
    return(CY) ;
}

/*-------------------------------------------------------------
功能：读一个字节数据
------------------------------------------------------------*/
unsigned char Read8Bit()
{
    unsigned char temp,rbyte=0;
    for (temp = 8;temp != 0;temp--)
    {
        AT24C02_SCL = 0;
        _nop_();
        rbyte = (rbyte << 1) | AT24C02_SDA;
        AT24C02_SCL = 1;
        _nop_();
    }
    return rbyte;
}

/*-------------------------------------------------------------
功能：从EEPROM中给定一个地址连续读NLEN个字节数据存放在以指针
nContent开头的往下内容。
------------------------------------------------------------*/
bit Read_Flash ( unsigned char *nContent, unsigned char nAddr, unsigned char nLen )
{
    unsigned char Addr;
    Addr = nAddr;
    Start_Cond();                        //写开始信号
    Write8Bit(WriteDeviceAddress);      //写驱动地址
    Write8Bit(Addr);                    //写从EEPROM中读的开始地址
    Start_Cond();                        //写开始信号
    Write8Bit(ReadDeviceAddress);        //写读数据指令
    while(--nLen)
    {
        *nContent=Read8Bit();              //读出内容
        nContent++;                        //指针加1
        Ack();                            //发确认信号
    }                                   
    *nContent=Read8Bit();               //读一字节
    NoAck();                            //没有确认信号
    Stop_Cond();                        //发停止信号
    return(0);                            //返回
}

/*-------------------------------------------------------------
功能：初始化EEPROM子程序内容为FF
------------------------------------------------------------*/
bit Init_Flash ( unsigned int nPage ) //    8 Byte/1Page init 0xFF 
{
    unsigned char nLen;
    unsigned char Addr;
    nLen=8;
    Addr=8 *nPage;
    
    Start_Cond();
    Write8Bit(WriteDeviceAddress);
    Write8Bit(Addr);
    for(;nLen!=0;nLen--)
    {
        if(Write8Bit(0xff)) break;    //if Write8Bit() Return 1 Write Flase
    }
    Stop_Cond();
        return(CY);
}

/*-------------------------------------------------------------
功能：从EEPROM中给定一个地址连续写NLEN个字节数据存放在以指针
nContent开头的往下内容。
------------------------------------------------------------*/
bit Write_Flash ( unsigned char *nContent, unsigned char nAddr,unsigned char nLen)
{
    unsigned char i,temp;
    unsigned char Addr;
    Addr = nAddr;
    Start_Cond();                    //写开始信号
    Write8Bit(WriteDeviceAddress);    //写驱动地址
    Write8Bit(Addr);                //写从EEPROM中写的开始地址 
    for(i = 0;i < nLen;i++)
    {
        if(Addr%8==0)                //每页8字节  //换页
        {
            Stop_Cond();
            _nop_();
            Start_Cond();
            Write8Bit(WriteDeviceAddress);
            Write8Bit(Addr);
        }
        temp = *nContent;
        if(Write8Bit(temp)) break;    //CY
        nContent++;
        Addr++;
    }
    Stop_Cond();                    //发停止信号
    return(CY);
}

/*-------------------------------------------------------------
主程序
功能：实现存储器EEPROM AT24C02的数据读写操作
------------------------------------------------------------*/
void main()
{
    unsigned char dat[16],i;
    
    Read_Flash(dat,0,16);    //读出AT24C02中从地址0开始依次往后16个字节放入dat数组中  
    Init_Flash(0);            //将AT24C02的第0页初始化为FF
    Read_Flash(dat,0,16);    //读出AT24C02中从地址0开始依次往后16个字节放入dat数组中
    
    for(i = 0;i < 16;i++ )
    {
         dat[i] = i;        //对数组dat初始化为0---F
    }     
    Write_Flash(dat,0,16);    //将dat数组中的数据写入AT24C02中地址从0开始
    Read_Flash(dat,1,16);    //读出AT24C02中从地址1开始依次往后16个字节放入dat数组中
    while(1)
    {
        i = 9;
    }
}