i2c.c

这是利用C51语言编写的读写AT24C512的程序

#include	<stdio.h>
#include	<stdlib.h>
#include	<string.h>
#include	<ctype.h>
#include	<absacc.h>
#include	<reg52.h>
#include	<usign.h>
#include	<float.h>
#include 	<INTRINS.h>

#include	"meter.h"

sbit	WP				=P2^5;
sbit	SCL				=P1^6;
sbit	SDA				=P1^7;

#define		SCL_HIGH	SCL=1;\
						_nop_();\
						_nop_();						
#define		SCL_LOW		SCL=0;\
						_nop_();\
						_nop_();
#define		SDA_HIGH	SDA=1;\
						_nop_();\
						_nop_();
#define		SDA_LOW		SDA=0;\
						_nop_();\
						_nop_();

#define 	WRITE256   0xa0			//低64K
#define 	READ256    0xa1

void 	I2CStart(void);
void 	I2CStop(void);
uchar	WaitAck(void);
void 	SendAck(void);
void 	SendNak(void);
void 	I2CSendByte(uchar i2c_sb_data);
uchar 	I2CReceiveByte(void);

/**********************************************************
Function    : I2CStart
Description : I2C bus start signal
Input       : none
Output      : none
***********************************************************/
void 	I2CStart(void)
{   
	SDA_HIGH;
	SCL_HIGH;
	SDA_LOW;
	SCL_LOW;
}

/**********************************************************
Function    : I2CStop
Description : I2C bus stop signal
Input       : none
Output      : none
***********************************************************/
void 	I2CStop(void)
{     
	SDA_LOW;
	SCL_HIGH;
	SDA_HIGH; 
	SCL_LOW;             
}
/**********************************************************
Function    : WaitAck for check ack
Description : wait I2C slave to respond ack
Input       : none
Output      : 0 - respond; 1 - no respond
***********************************************************/
uchar 	WaitAck(void)
{
	uchar	bAck;
	
	SDA_HIGH;
	SCL_HIGH;
	if(SDA==0)
		bAck=OK;
	else
		bAck=NOK;
	SCL_LOW;
	return	bAck;
}
/**********************************************************
Function    : SendAck
Description : send ack to I2C slave 
Input       : none
Output      : none
***********************************************************/
void 	SendAck(void)
{
	SDA_LOW;
	SCL_HIGH;
	SCL_LOW;
	SDA_HIGH;	
}
/**********************************************************
Function    : SendNak
Description : send not ack signal to I2C slave
Input       : none
Output      : none
***********************************************************/
void 	SendNak(void)
{
	SDA_HIGH;
	SCL_HIGH;
	SCL_LOW;
	SDA_LOW;	
}

/**********************************************************
Function    : I2CSendByte
Description : send a byte to I2C slave
Input       : data - the byte to be sent
Output      : none
***********************************************************/
void 	I2CSendByte(uchar bChar)
{
	uchar	i;
	for(i=0;i<8;i++)
	{
		if(	bChar&0x80)
		{
			SDA_HIGH;
			SCL_HIGH;
			SCL_LOW;
		}
		else
		{
			SDA_LOW;
			SCL_HIGH;
			SCL_LOW;
		}
		bChar<<=1;
	}
}

/**********************************************************
Function    : I2CReceiveByte
Description : Receive a byte from I2C slave
Input       : none
Output      : the byte received
***********************************************************/
uchar 	I2CReceiveByte(void)
{
	uchar	i,bChar;
	
	bChar=0;
	SDA=1;						//input init
	for(i=0;i<8;i++)
	{
		bChar<<=1;
		SCL_HIGH;
		if(SDA==1)
			bChar|= 0x01;
		else
			bChar&= 0xfe;		
		SCL_LOW;
	}
	return	bChar;
}

/*                  
功能：I2C芯片初始化
输入：none
输出: none
注意：
*/        
void	vInitI2C(void)
{
	WP=1;
	SCL_LOW;							
	SDA_LOW;
}			

/* 		                 
功能：	读I2C
输入：	
		Sla:		芯片地址(A0:EEPROM1;A4:EEPROM2)
		Address:	片内首地址
		Send_Data:	数据地址
		len:      	长度(<=128)
输出: 	0:正确; 1: 错误
注意：  
*/        
uchar 	IRcvStr( uchar  Sla,uint  Address ,uchar  *RcvData ,uchar  len)
{
	uchar	i;

	I2CStart();								
	I2CSendByte(Sla);						//SEND DEVICE ADDRESS
	if(WaitAck())
		goto	I2CReadError;
	I2CSendByte( (uchar)(Address>>8) );		//SEND ADDRESS HIGH
	if(WaitAck())
		goto	I2CReadError;
	I2CSendByte( (uchar)Address );			//SEND ADDRESS LOW
	if(WaitAck())
		goto	I2CReadError;

	I2CStart();										
	Sla|=0x01;								//read bit=1		
	I2CSendByte(Sla);						//SEND DEVICE ADDRESS	
	if(WaitAck())
		goto	I2CReadError;
			
	for(i=0;i<len;i++)
	{
		RcvData[i]=I2CReceiveByte();		//SEND DATA
		if(i==len-1)
			SendNak();						//发送完最后字节，发送NAK
		else
			SendAck();
	}
	I2CStop();	
	return	OK;
I2CReadError:
	I2CStop();	
	return	NOK;
}

/* 		                 
功能：	页写I2C
输入：	
		Sla:		芯片地址(A0:EEPROM1;A4:EEPROM2)
		Address:	片内首地址
		Send_Data:	数据源地址
		len:      	长度(<=128)
输出: 	0:正确; 1: 时序错误; 2:写入的数据读出后不对
注意：  不能跨页
*/        
uchar 	ISendStr( uchar  Sla,uint  Address ,uchar  *Send_Data ,uchar  len )
{
	uchar	i,bI2CReadData;

//	memcpy(abI2CReadData,Send_Data,len);	//暂存要写的数据
	WP=0;
	I2CStart();								
	I2CSendByte(Sla);						//SEND DEVICE ADDRESS
	if(WaitAck())
		goto	I2CWriteError;
	I2CSendByte( (uchar)(Address>>8) );		//SEND ADDRESS HIGH
	if(WaitAck())
		goto	I2CWriteError;	
	I2CSendByte( (uchar)Address );			//SEND ADDRESS LOW
	if(WaitAck())
		goto	I2CWriteError;	
	for(i=0;i<len;i++)
	{
		I2CSendByte(Send_Data[i]);			//SEND DATA
		if(WaitAck())
			goto	I2CWriteError;
	}
	I2CStop();

	for(;;)									//查询是否写完
	{	
		I2CStart();								
		I2CSendByte(Sla);					
		if(!WaitAck())
			break;
	}
	WP=1;
    _Delay(10);	
        
	for(i=0;i<len;i++)
	{
		IRcvStr(Sla, Address ,&bI2CReadData ,1);		//写后读
		Address++;
		if( bI2CReadData!=Send_Data[i] ) 
			goto	I2CWriteError;
	}
/*
	IRcvStr(Sla, Address ,Send_Data ,len);				//写后读	
	if (memcmp(abI2CReadData, Send_Data, len) == 0 )	
		return	2;
*/	
	_Delay(100);	
	return OK;

I2CWriteError:
	I2CStop();	
	WP=1;
	_Delay(100);		
//	return	NOK;
	return	0;
}