eeprom.c

飞利浦10碟VCD控制程序

//#pragma  ot(6,SIZE)
#include <REG52.H>
#include <intrins.h>
#include <constant.h>


/*
#define  ERRORCOUNT 10
sbit     SDA=P0^0;
sbit     SCL=P0^1;

#define	EEPROM_WRITE	0xA0
#define	EEPROM_READ 	0xA1
*/
void IICStart(void);
void IICStop(void);
bit IICRecAck(void);
void IICACK(void);
void IICNoAck(void);
void IICSendByte(unsigned char sendbyte);
unsigned char IICReceiveByte(void);
void Delay(unsigned char DelayCount);
bit ReadEEPROM(unsigned char raddr,unsigned char *rdata,unsigned char num);
bit WriteEEPROM(unsigned char waddr,unsigned char *wdata,unsigned char num);


/*****************以下是对IIC总线的操作子程序***/
/*****************启动总线**********************/
void IICStart(void)
{
SCL=0;                  //
SDA=1;
SCL=1;
_nop_();
_nop_();
_nop_();
SDA=0;
_nop_();
_nop_();
_nop_();
SCL=0;
SDA=1;                  //
}

/*****************停止IIC总线****************/
void IICStop(void)
{
SCL=0;
SDA=0;
SCL=1;
_nop_();
_nop_();
_nop_();
SDA=1;
_nop_();
_nop_();
_nop_();
}

/**************检查应答位*******************/
bit IICRecAck(void)
{
SCL=0;
SDA=1;
SCL=1;
_nop_();
_nop_();
_nop_();
CY=SDA;                 //因为返回值总是放在CY中的
SCL=0;
return(CY);
}

/***************对IIC总线产生应答*******************/
void IICACK(void)
{
SDA=0;
SCL=1;
_nop_();
_nop_();
_nop_();
SCL=0;
_nop_();
_nop_();
_nop_();
SDA=1;
}

/*****************不对IIC总线产生应答***************/
void IICNoAck(void)
{
SDA=1;
SCL=1;
_nop_();
_nop_();
_nop_();
SCL=0;
}

/*******************向IIC总线写数据*********************/
void IICSendByte(unsigned char sendbyte)
{
unsigned char data j=8;
for(;j>0;j--)
   {
   SCL=0;
   sendbyte<<=1;        //无论C51怎样实现这个操作，始终会使CY=sendbyte^7;
   SDA=CY;
   SCL=1;
   }
SCL=0;
}

/**********************从IIC总线上读数据子程序**********/
unsigned char IICReceiveByte(void)
{
register receivebyte,i=8;
SCL=0;
while(i--)
   {
   SCL=1;
   receivebyte=(receivebyte<<1)|SDA;
   SCL=0;
   }
return(receivebyte);
}

/***************一个简单延时程序************************/
void Delay(unsigned char DelayCount)
{
while(DelayCount--);
}


//----------------------EEPROM AT24C02 Operation----------------
//#define	EEPROM_WRITE	0xA0
//#define	EEPROM_READ 	0xA1

//raddr: 24C02 read first address
//rdata: data buffer
//num:   valid data num
bit ReadEEPROM(unsigned char raddr,unsigned char *rdata,unsigned char num)
{
	unsigned char i;
	bit errorflag=1;
	i=ERRORCOUNT;
	while(i--)
	{
		IICStart();
		IICSendByte(EEPROM_WRITE);
		if(IICRecAck())
			continue;
		IICSendByte(raddr);
		if(IICRecAck())
			continue;
		IICStart();
		IICSendByte(EEPROM_READ);
		if(IICRecAck())
			continue;
		while(--num)
		{
			*rdata++=IICReceiveByte();
			IICACK();
		}
		*rdata=IICReceiveByte();        //read last byte data
		IICNoAck();
		IICStop();
		errorflag=0;
		break;
	}
	return(errorflag);
}


//waddr: 24C02 write first address
//wdata: data buffer
//num:   valid data num
//if success return 0,else return 1;
bit WriteEEPROM(unsigned char waddr,unsigned char *wdata,unsigned char num)
{
	unsigned char i;
	bit errorflag=0;
	i=ERRORCOUNT;
	while(i--)
	{
		IICStart();
		IICSendByte(EEPROM_WRITE);
		if(IICRecAck())
			continue;
		IICSendByte(waddr);
		if(IICRecAck())
			continue;
		while(num--)
		{
			IICSendByte(*wdata++);
			if(!IICRecAck())
				continue;
			errorflag=1;
			break;
		}
		if(!errorflag)
			break;
	}
	IICStop();
	Delay(255);
	Delay(255);
	Delay(255);
	Delay(255);
	if(i==0)
		errorflag=1;
	return(errorflag);
}

//----------------------END EEPROM AT24C02 Operation----------------