下面是用普通C51实现的I2C基本电平模拟函数和通用函数。 

       /*  电平模拟函数和基本读写函数 
       void IIC_Start(void); 
       void IIC_Stop(void); 
       void SEND_0(void); 
       void SEND_1(void); 
       bit Check_Acknowledge(void); 
       void Write_Byte(uchar b)reentrant; 
       bit Write_N_Bytes(uchar *buffer,uchar n)reentrant; 
       bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer); 
       uchar Read_Byte(void)reentrant; 
   */ 

       #include 
       #include 
       #include 
       #include"aiic_51.h" 

       sbit SCL=P1^6; 
       sbit SDA=P1^7; 

       void DELAY(uint t) 
       { 
           while(t!=0) 
               t--; 
       } 

       void IIC_Start(void) 
       { 
           //启动I2C总线的函数，当SCL为高电平时使SDA产生一个负跳变 
           SDA=1; 
           SCL=1; 
           DELAY(DELAY_TIME); 
           SDA=0; 
           DELAY(DELAY_TIME); 
           SCL=0; 
           DELAY(DELAY_TIME); 
       } 

       void IIC_Stop(void) 
       { 
           //终止I2C总线，当SCL为高电平时使SDA产生一个正跳变 
           SDA=0; 
           SCL=1; 
           DELAY(DELAY_TIME); 
           SDA=1; 
           DELAY(DELAY_TIME); 
           SCL=0; 
           DELAY(DELAY_TIME); 
       } 

       void SEND_0(void) 
       { 
           //发送0，在SCL为高电平时使SDA信号为低 
           SDA=0; 
           SCL=1; 
           DELAY(DELAY_TIME); 
           SCL=0; 
           DELAY(DELAY_TIME); 
       } 

       void SEND_1(void) 
       { 
           //发送1，在SCL为高电平时使SDA信号为高 
           SDA=1; 
           SCL=1; 
           DELAY(DELAY_TIME); 
           SCL=0; 
           DELAY(DELAY_TIME); 
       } 

       bit Check_Acknowledge(void) 
       { 
           //发送完一个字节后检验设备的应答信号 
           SDA=1; 
           SCL=1; 
           DELAY(DELAY_TIME/2); 
           F0=SDA; 
           DELAY(DELAY_TIME/2); 
           SCL=0; 
           DELAY(DELAY_TIME); 
           if(F0==1) 
               return FALSE; 
           return TRUE; 
       } 

       void Write_Byte(uchar b)reentrant 
       { 
           //向IIC总线写一个字节 
           uchar i; 
           for(i=0;i<8;i++) 
               if((b<                   SEND_1(); 
               else 
                   SEND_0(); 
       } 

       bit Write_N_Bytes(uchar *buffer,uchar n)reentrant 
       { 
           //向I2C总线写n个字节 
           uchar i; 
           IIC_Start(); 

           for(i=0;i           { 
               Write_Byte(buffer[i]); 
               if(!Check_Acknowledge()) 
                   { 
                       IIC_Stop(); 
                       return(i==n); 
                   } 
           } 

           IIC_Stop(); 
           return TRUE; 
       } 

       uchar Read_Byte(void)reentrant 
       { 
           //从I2C总线读一个字节 
           uchar b=0,i; 
           for(i=0;i<8;i++) 
           { 
               SDA=1;    //释放总线 
               SCL=1;    //接受数据 
               DELAY(10); 
               F0=SDA; 
               DELAY(10); 
               SCL=0; 
               if(F0==1) 
                   { 
                       b=b<<1; 
                       b=b 0x01; 
                   } 
               else 
                   b=b<<1; 
           } 
           return b; 
       } 

       bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer) 
       { 
           //从I2C总线读n个字节 
           uchar i; 
           IIC_Start(); 
           Write_Byte(SlaveAdr);        //向总线发送接收器地址 
           if(!Check_Acknowledge())     //等待接收器应答信号 
               return FALSE; 
           for(i=0;i               { 
                   buffer[i]=Read_Byte(); 
                   if(i!=n) 
                       SEND_0();    //发送应答 
                   else 
                       SEND_1();    //发送非应答 
               } 
           IIC_Stop(); 
           return TRUE; 
       } 
  
       使用上述代码，你可以在51上用P1口模拟I2C