51单片机I2C总线使用

适合EEPROM存储和PCF8591A/D-D/A转换等。。

/*************************************************************************************
**************
**************************************************************************************/


#ifndef           __I2C_H__
#define           __I2C_H__


#include "I2C.h"
#define uchar unsigned char
#define uint  unsigned int

sbit SCL = P2^1;
sbit SDA = P2^0;

//void delay()
//{;;}

void I2C_start()
{
	SDA=1;
	delay();
	SCL=1;
	delay();
	SDA=0;
	delay();
}
//
void I2C_stop()
{
	SDA=0;
	delay();
	SCL=1;
	delay();
	SDA=1;
	delay();
}
//
void I2C_respons()
{
	uchar i;
	SCL=1;
	delay();
	while((SDA==1)&&(i<250))i++;
	SCL=0;
	delay();
}
//
void I2C_init()
{
	SDA=1;
	delay();
	SCL=1;
	delay();
}

uchar I2C_read_byte()
{
	uchar i,k;
	SCL=0;
	delay();
	SDA=1;
	delay();
	for(i=0;i<8;i++)
	{
		SCL=1;
		delay();
		k=(k<<1)|SDA;
		SCL=0;
		delay();
	}
	return k;
}
//
void I2C_write_byte(uchar date)
{
	uchar i,temp;
	temp=date;
	for(i=0;i<8;i++)
	{
		temp=temp<<1;
		SCL=0;
		delay();
		SDA=CY;
		delay();
		SCL=1;
		delay();
		SCL=0;
	  delay();		
	}	
	SDA=1;
	delay();
}
//
void I2C_write_process(uchar addr,uchar cmd,uchar dat)
{
	I2C_start();
	I2C_write_byte(addr);
	I2C_respons();
	I2C_write_byte(cmd);
	I2C_respons();
	I2C_write_byte(dat);
	I2C_respons();
	I2C_stop();
}
//
uint I2C_read_process(uchar addr,uchar cmd)
{
	uint date;
	
	I2C_start();
	I2C_write_byte(addr);
	I2C_respons();
	I2C_write_byte(cmd);
	I2C_respons();
	
	I2C_start();
	I2C_write_byte(addr+1);
	I2C_respons();
	date = I2C_read_byte();
	I2C_respons();
	I2C_stop();
	
	return date;
}



#endif