作者:高鹏     来源：本站原创

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#include <reg52.h>
#include<absacc.h>
#include<intrins.h>
// extern void DelayMs(unsigned int);
//extern void Read24c02(unsigned char *RamAddress,
//                                     unsigned char RomAddress,unsigned char bytes);
// extern void Write24c02(unsigned char *RamAddress,
//                                         unsigned char RomAddress,unsigned char bytes);

/****************************************************************/
#define WriteDeviceAddress 0xa0 //写格式
#define ReadDviceAddress 0xa1 //读格式
#define uchar unsigned char
#define uint unsigned int
#define PA8255 XBYTE[0x3ffc]
#define PB8255 XBYTE[0x3ffd]
#define PC8255 XBYTE[0x3ffe]                      
#define COM8255 XBYTE[0x3fff]
/***************************************************************/
void DelayMs(uchar number);
void Start();
void Stop();
void Ack();   //应答格式
void NoAck(); //非应答格式
bit TestAck(); //检查应答的ACK
void Write8Bit(uchar input);//写一个字节
void Write24c02(uchar *Wdata,uchar RomAddress, //写入I2C程序
                                                   uchar number);
uchar Read8Bit();   //读一个字节
void Read24c02(uchar *RamAddress,uchar RomAddress, //读出I2C程序
                                                 uchar bytes) ;
void Delay(uchar i) ;
sbit SCL=P1^4;
sbit SDA=P1^5;
sbit DOG=P3^7;
sbit cs138=P1^6;
sbit led0=P1^0;
sbit led1=P1^1;
sbit led2=P1^2;
sbit led3=P1^3;
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/***************************************************************/
uchar T[1]; //I2C数据存储区
uchar   code tab[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,
         0x77,0x7c,0x39,0x5e,0x79,0x71};//0~f

void main()
{
uchar tmp;
cs138=0;
P1=0;
COM8255=0X88;
Read24c02(T,0x00,1);//读程序从0X00单元开始，读出一个字节
while(1)
{
   {
     tmp=T[0];if(tmp>9){T[0]=0;tmp=0;}else{T[0]++;}
     Write24c02(T,0x00,1);//写程序从0X00单元开始，写入一个字节
   }
   while(1)
     {PB8255=tab[tmp];led3=1;Delay(2);led3=0;}
   }
}
void DelayMs(uchar number)
{
uchar temp;
for(;number!=0;number--,DOG=!DOG)
   {
   for(temp=112;temp!=0;temp--) {}
   }
}
/*******************启动I2C*/
void Start()
{
SDA=1;
SCL=1;
SDA=0;
SCL=0;
}
/*********************///停止I2C
void Stop()
{
SCL=0;
SDA=0;
SCL=1;
SDA=1;
}
/**********************/
void Ack()   //应答格式
{
SDA=0;
SCL=1;
SCL=0;
SDA=1;
}
/***********************/
void NoAck()   //应答格式
{
SDA=1;
SCL=1;
SCL=0;
}
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/*************************************/
bit TestAck() //检查应答的ACK
{
bit ErrorBit;
SDA=1;
SCL=1;
ErrorBit=SDA;
SCL=0;
return(ErrorBit);
}
/*************************************/
void Write8Bit(uchar input) //写一个字节
{
uchar temp;
for(temp=8;temp!=0;temp--)
   {
   if(input&0x80)SDA=1;
   else SDA=0;
   SCL=1;
   SCL=0;
   input=input<<1;
   }
}
/****************************************/
void Write24c02(uchar *Wdata,uchar RomAddress, //写入I2C程序
                                                   uchar number)
{
Start();           //开始条件
Write8Bit(WriteDeviceAddress); //写8位设备地址
TestAck();          
Write8Bit(RomAddress);
TestAck();
for(;number!=0;number--)
{
   Write8Bit(*Wdata);
   TestAck();
   Wdata++;
}
Stop();
DelayMs(10);
}
/***************************************************/
uchar Read8Bit()   //读一个字节
{
uchar temp,rbyte=0;
for(temp=8;temp!=0;temp--)
   {
   SCL=1;
   rbyte=rbyte<<1;
   if(SDA)rbyte|=0x01;
   else rbyte|=0x00;
   SCL=0;
   }
return(rbyte);
}
void Read24c02(uchar *RamAddress,uchar RomAddress, //读出I2C程序
                                                 uchar bytes)
{
Start();
Write8Bit(WriteDeviceAddress);
TestAck();
Write8Bit(RomAddress);
TestAck();
Start();
Write8Bit(ReadDviceAddress);
TestAck();
while(bytes!=0)
{
*RamAddress=Read8Bit();
Ack();         //应答
RamAddress++;
bytes--;
}
*RamAddress=Read8Bit();
NoAck();       //非应答
Stop();         //结束条件
}
//延时程序
void Delay(uchar i)           //延时程序,i是形式参数
{
uchar j;
while(i--)                         //变量i由实际参数传入一个值,因此i不能赋初值
for(j=0;j<125;j++);
}