www.pudn.com > PLC.rar > I2c.c

#include "reg51.h" 
#include "intrins.h" 
 
#define salve_addr 0xa0 
#define read   0x01 
#define write  0x00; 
 
void I2c_Start(); 
void I2c_Stop(); 
void I2c_Wait(); 
void Ack(bit ); 
bit Send_Byte(unsigned char); 
bit Read_Byte(unsigned char *); 
 
extern unsigned char error; 
extern unsigned char data intr[6]; 
sbit Sda = P1^6; 
sbit Scl = P1^7; 
 
bit I2c_Read(unsigned char address,unsigned char count) 
{ 
    unsigned char mode,i; 
  
	mode = salve_addr | write; 
    I2c_Start();                         error++; 
    if (Send_Byte(mode) == 0) 
	{                                     error++; 
	   if (Send_Byte(address) == 0) 
	   {                                    error++; 
          I2c_Start(); 
		  mode = salve_addr | read; 
          if (Send_Byte(mode) == 0) 
		  {                                  error++; 
             for (i = 0;i < count - 1;i++) 
 	         {                                 error++; 
	            Read_Byte(&intr[i]); 
                Ack(0); 
             }  
			 Read_Byte(&intr[i]); 
			 Ack(1); 
   	         if (i == count - 1) 
			 {   
			     I2c_Stop(); 
		         return 0; 
			 } 
		   } 
	   } 
	} 
	I2c_Stop(); 
	return 1;                       // error 
} 
 
bit I2c_Write(unsigned char address,unsigned char Write_Data) 
{ 
     unsigned char mode; 
     
	 mode = salve_addr; 
	 mode = mode  | write; 
	 I2c_Start(); 
	 if (Send_Byte(mode) == 0) 
	 {   
	     if (Send_Byte(address) == 0) 
		     if (Send_Byte(Write_Data) == 0) 
  			 { 
			      I2c_Stop(); 
                  return 0; 
			 } 
	 } 
	 I2c_Stop(); 
	 return 1; 
} 
 
void I2c_Start() 
{ 
    Sda = 1; 
	Scl = 1; 
	I2c_Wait(); 
	Sda = 0; 
	I2c_Wait(); 
	Scl = 0; 
} 
 
void I2c_Stop() 
{ 
    Sda = 0; 
	I2c_Wait(); 
	Scl = 1; 
	I2c_Wait(); 
	Sda = 1; 
} 
 
void I2c_Wait() 
{ 
    _nop_(); 
	_nop_(); 
} 
 
bit Send_Byte(unsigned char Send_Data) 
{ 
    unsigned char i; 
	bit b; 
  
	for (i = 0;i < 8;i++) 
	{ 
	   if (Send_Data & 0x80) 
	      Sda = 1; 
	   else  
	      Sda = 0; 
	   Send_Data = Send_Data << 1; 
	   Scl = 1; 
	   I2c_Wait(); 
	   Scl = 0; 
	   I2c_Wait(); 
    } 
	Sda = 1; 
	I2c_Wait(); 
	Scl = 1; 
	I2c_Wait(); 
    b = Sda; 
	Scl = 0; 
	I2c_Wait(); 
	return b; 
} 
 
bit Read_Byte(unsigned char *Read_Data) 
{ 
    unsigned char i,temp = 0; 
 
	for(i = 0;i < 8;i++) 
	{ 
	   Scl = 1; 
	   I2c_Wait(); 
	   temp <<= 1; 
	   if (Sda == 1) 
	      temp = temp | 0x01; 
	   Scl = 0; 
	   I2c_Wait(); 
    } 
	*Read_Data = temp; 
    return 0; 
} 
 
void Ack(bit b) 
{ 
    Sda = b; 
    Scl = 1; 
	I2c_Wait(); 
	Scl = 0; 
	Sda = 1; 
} 
 
/*bit Read_Test(unsigned char address) 
{ 
    bit b; 
    I2c_Start(); 
    b = Send_Byte(0xa0); 
	b |= Send_Byte(address); 
	I2c_Start(); 
	b |= Send_Byte(0xa1); 
    Read_Byte(&intr[0]); 
	Ack(0); 
	Read_Byte(&intr[1]); 
	Ack(0); 
	Read_Byte(&intr[2]); 
	Ack(1); 
    I2c_Stop(); 
	return b; 
}  */