24cxx_twi.h

24IIC的源代码

typedef unsigned char     uint8; 
typedef unsigned int      uint16; 

typedef  union reccnt 
{ 
 uint16 rcnt; 
 uint8  rcntl[2]; 
}LngToChar; 

#define wr_24c64_cmd      0xA0 
#define rd_24c64_cmd      0xA1 
         
#define START 0x08   
#define RE_START 0x10   
#define MT_SLA_ACK 0x18   
//#define MT_SLA_ACK 0x38   
#define MT_SLA_NOACK 0x20   
#define MT_DATA_ACK  0x28   
#define MT_DATA_NOACK 0x30   
#define MR_SLA_ACK  0x40   
#define MR_SLA_NOACK 0x48   
#define MR_DATA_ACK 0x50   
#define MR_DATA_NOACK 0x58  
   
#define Start()         (TWCR=(1<<TWINT)|(1<<TWSTA)|(1<<TWEN))   
#define Stop()          (TWCR=(1<<TWINT)|(1<<TWSTO)|(1<<TWEN))   
#define Wait()          {while(!(TWCR&(1<<TWINT)));}   
#define TestAck()       (TWSR&0xf8)  
#define SetAck()        (TWCR|=(1<<TWEA))   
#define SetNoAck()      (TWCR&=~(1<<TWEA))   
#define Twi()           (TWCR=(1<<TWINT)|(1<<TWEN))  
#define Write8Bit(x)    {TWDR=(x);TWCR=(1<<TWINT)|(1<<TWEN);} 
  
uint8 WriteByte(uint16 RomAddress,uint8 Wdata);
uint8 ReadByte(uint16 RomAddress);

//******************************************    
uint8 WriteByte(uint16 RomAddress,uint8 Wdata)    
{       
 LngToChar ltg; 
          
 ltg.rcnt=RomAddress; 

 _CLI(); 
 Start();//twi 
 Wait();   
 if(TestAck()!=START) goto wr_exit;//ACK 0x08    

 Write8Bit(wr_24c64_cmd);// 
 Wait();   
 if(TestAck()!=MT_SLA_ACK) goto wr_exit;//ACK MT_SLA_ACK 0x18  
 
 Write8Bit(ltg.rcntl[1]);  //写操作单元的高8位地址    
 Wait(); 
 if(TestAck()!=MT_DATA_ACK) goto wr_exit;//ACK   

 Write8Bit(ltg.rcntl[0]);   //写操作单元的低8位地址    
 Wait(); 
 if(TestAck()!=MT_DATA_ACK) goto wr_exit;//ACK   
    
 Write8Bit(Wdata);// 
 Wait();   
 if(TestAck()!=MT_DATA_ACK) goto wr_exit;//ACK      
      
 Stop();// 
 delay_ms(30);//   
 _SEI(); 
 return 0;   
 wr_exit://出错退出 
   Stop();// 
   _SEI(); 
 return 1; 
}  
  
//******************************************   
uint8 ReadByte(uint16 RomAddress) 
{   
 uint8 temp;  
 LngToChar ltg; 
 _CLI(); 
 ltg.rcnt=RomAddress; 

 Start();  
 Wait();  
 if (TestAck()!=START) goto re_exit;//ACK  
                        
 Write8Bit(wr_24c64_cmd);//  
 Wait();               
 if (TestAck()!=MT_SLA_ACK) goto re_exit;//ACK   
           
 Write8Bit(ltg.rcntl[1]); //写操作单元的高8位地址    
 Wait();   
 if (TestAck()!=MT_DATA_ACK) goto re_exit;   
           
 Write8Bit(ltg.rcntl[0]);  //写操作单元的低8位地址       
 Wait();   
 if (TestAck()!=MT_DATA_ACK) goto re_exit; 
           
 Start();//twi 
 Wait();   
 if (TestAck()!=RE_START)  goto re_exit;   
            
 Write8Bit(rd_24c64_cmd);//   
 Wait();   
 if(TestAck()!=MR_SLA_ACK)  goto re_exit;//ACK   
               
 Twi();//启动主I2C读方式 
 Wait();   
 if(TestAck()!=MR_DATA_NOACK) goto re_exit;//ACK  MR_DATA_NOACK 0x58   
   
 temp=TWDR;// 读取I2C接收的数据      
 Stop();//I2C停止  

 _SEI(); 
 return temp; 

 re_exit://出错退出 
 Stop(); 
 _SEI(); 
 return 0;  
}