24cxx.c

I2C 24c02 芯片读写程序

//---------------------------------------------------------------------------//
//-------24cxx.c-------------------------------------------------------------//
//----I2C的读写时序的软件模拟---------------------------------------------------//
//----by gg------------------------------------------------------------------//
//----at 2006.02.27----------------------------------------------------------//
//---------------------------------------------------------------------------//
//#include <reg51.h>
#include <sanxian.h>
#define HIGH 1
#define LOW  0
#define FALSE 0
#define TRUE ~FALSE
#define WRITE 0xA0 //24Cxx的地址和方向位W
#define READ  0xA1  //24Cxx的地址和方向位R
//#define BLOCK_SIZE 12   //定义指定字节个数

//idata uchar EAROMImage[BLOCK_SIZE];
sbit SCL = P1^1;
sbit SDA = P2^7;
extern uchar idata comarr[10];
//---------------------------------------------------------------------------//
//------void I_start(void);--------------------------------------------------//
//-------I2C总线的起始位-------------------------------------------------------//
//---------------------------------------------------------------------------//
void I_start()
{
	SCL = HIGH;
	delay(0);
	SDA = LOW;
	delay(0);
	SCL = LOW;
	delay(0);
}

//----------------------------------------------------------------------------//
//-------void I_stop();--------------------------------------------------------//
//-----I2C总线的停止位---------------------------------------------------------//
//----------------------------------------------------------------------------//
void I_stop()
{
	SDA = LOW;
	delay(0);
	SCL = HIGH;
	delay(0);
	SDA = HIGH;
	delay(0);
	SCL = LOW;
	delay(0);
}

//-------------------------------------------------------------------------//
//-----void I_init();------------------------------------------------------//
//-----I2C总线的初始化，应首先调用该函数---------------------------------------//
//-------------------------------------------------------------------------//
void I_init()
{
	SCL = LOW;
	I_stop();
}

//-------------------------------------------------------------------------------//
//-----bit I_clock();------------------------------------------------------------//
//-----I2C的总线时钟信号，返回时钟为高期间SDA信号线上的状态。可用于数据的发送和接收。------//
//-------------------------------------------------------------------------------//
bit I_clock()
{
	bit sample;
	SCL = HIGH;
	delay(0);
	sample = SDA;
	SCL = LOW;
	delay(0);
	return (sample) ;
}

//---------------------------------------------------------------------------------//
//-------bit I_send(uchar I_data);-------------------------------------------------//
//-------向I2C发送8位数据，并请求一个应答信号ACK。如果收到ACK返回1（TRUE），否则0（FALSE）--//
//----------------------------------------------------------------------------------//
bit I_send(uchar I_data)
{
	register uchar i;
	for (i=0;i<8;i++)
	{
		SDA = (bit)(I_data & 0x80);
		I_data = I_data << 1;
		I_clock();
	} //end for
	//请求应答信号
	SDA = HIGH;
	return ( ~I_clock() );
}

//--------------------------------------------------------------------------------------------//
//--------uchar I_receive()-------------------------------------------------------------------//
//--------从I2C上接受8位数据信号，并作为一个字节返回，不回送ACK。在调用本函数之前要保证SDA浮置，即8051该口线置1--//
//--------------------------------------------------------------------------------------------//
uchar I_receive()
{
	uchar I_data = 0 ;
	register uchar i;
	for(i=0;i<8;i++)
	{
		I_data *= 2;
		if(I_clock())
		I_data++; //end if
	} //endfor
	return (I_data) ;
}

//---------------------------------------------------------------------------------------------------//
//-------void I_ack()--------------------------------------------------------------------------------//
//-------向I2C总线发送一个应答信号ACK，一秀般用于连续数据读取时---------------------------------------------//
//---------------------------------------------------------------------------------------------------//
void I_ack()
{
	SDA = LOW;
	I_clock();
	SDA = HIGH;
}
//up for I2C



//below is 24c02
//---------------------------------------------------------------------------------------------------------//
//----bit E_address(uchar add)-----------------------------------------------------------------------------//
//---向24CXX写入器件地址和一个指定的字节地址--------------------------------------------------------------------//
//----------------------------------------------------------------------------------------------------------//
bit E_address(uchar add)
{
	I_start();
	if(I_send( WRITE ))
		return (I_send(add));
	else
		return ( FALSE );
		//endif
}
//------------------------------------------------------------------------------------------------------------//
//---------bit E_read_block(uchar startadd,uchar n,uchar *p);---------------------------------------------------------------//
//----从24CXX读数据，从startadd开始，读n个字节，放入地址p中-------------------------------------------//
//------------------------------------------------------------------------------------------------------------//
bit E_read_block(uint idata startadd , uchar idata n, uchar *p)
{
	register uint i;
	//from address 0
	if(E_address(startadd))
	{
		I_start(); //start again
		if(I_send(READ))
		{
			for(i=0;i<=n;i++)
			{
				p[i] = (I_receive());
				if(i!=n)
					I_ack();
				else
				{
					I_clock();
					I_stop();
				} //endif
			}//endfor
			return (TRUE);
		}
		else
		{
			I_stop();
			return (FALSE);

		} //endif
	}
	else
	{
		I_stop();
		return (FALSE);
	}  
	//endif
}