C语言 union 共用体,IIC通信,24C02存储数据

#ifndef __IIC_H__
#define __IIC_H__
#include "reg51.h"
#define u8 unsigned char
#define u16 unsigned int	
 
extern void IIC_Delay(u16 x);
extern void IIC_Start();
extern void IIC_Stop ();
extern void IIC_SendByte(u8 dat);
extern u8 IIC_WaitACK ();
extern u8 IIC_ReciveByte();
extern void IIC_SendACK();
extern void IIC_SendNoACK ();
#endif

#include "IIC.h"
sbit IIC_SCL = P1^4;
sbit IIC_SDA = P1^3;
/**
* 1010 000 1 -->0xA1 read
* 1010 000 0 -->0xA0 write
*/
void IIC_Delay(u16 x) {
	while(x--);
}
 
void IIC_Start() {//产生IIC启动时序
	IIC_SCL = 1;
	IIC_SDA = 1;
	IIC_Delay(4);
	IIC_SDA = 0;
	IIC_Delay(4);
	IIC_SCL = 0;
}
 
void IIC_Stop () {//产生IIC停止时序
	IIC_SCL = 0;
	IIC_Delay(4);
	IIC_SDA = 0;
	IIC_Delay(4);
	IIC_SCL = 1;
	IIC_Delay(4);
	IIC_SDA = 1;
}
 
void IIC_SendByte(u8 dat) {
	u8 i;
	for(i=0;i<8;i++) {
		IIC_SCL = 0;
		if(dat>>7) {
			IIC_SDA = 1;	
		} else {
			IIC_SDA = 0;
		}
		IIC_SCL = 1;
		dat<<=1;	
	}
}
 
u8 IIC_WaitACK () {
	u16 t=0;
	IIC_SCL = 0;
	IIC_SDA = 1;
	IIC_SCL = 1;
 
	while(IIC_SDA) { //等待从机拉低SDA
		if(t++>=10000) {
			return 1;//等待应答失败
		}		
	}
	IIC_SCL = 0;
	return 0;//等待应该成功
}
 
u8 IIC_ReciveByte() {
	u8 d,i;
	for(i=0;i<8;i++) {
		d<<=1;
		IIC_SCL = 1;
		if(IIC_SDA) {
			d++;//d|=0x01;	
		}
		IIC_SCL = 0;
	}
	return d;
}
 
void IIC_SendACK () { //主机发送收到数据确认应答
	IIC_SCL = 0;
	IIC_SDA = 0;
	IIC_SDA = 1;
	IIC_SCL = 1;
}
 
void IIC_SendNoACK () { //主机发送收到数据确认非应答
	IIC_SCL = 0;
	IIC_SDA = 0;
	IIC_SDA = 1;
}

#ifndef __24C02_H__
#define __24C02_H__
#include "iic.h"
extern void Write_24c02(u8 add, u8 dat);
extern u8 Read_24c02(u8 add);
extern void Save_u16(u8 add, u16 n);
extern u16 Read_u16(add);
extern void Save_Float(u8 add, float n);
extern float Read_Float(add);
#endif

#include "24c02.h"
typedef union {
	float t;
	u8 s[4];
} fltcom;  //定义一个共用体
 
void Write_24c02(u8 add, u8 dat) {//将dat 写入到24c02的add地址
	u8 st;
	IIC_Start();
	IIC_SendByte(0xA0);//1010 000 0
	st = IIC_WaitACK();
 
	if(st != 0) {//等待应答失败，故障提示
		return;
	}
 
	IIC_SendByte(add);
	IIC_WaitACK();
 
	IIC_SendByte(dat);
	IIC_WaitACK();
	IIC_Stop();
	//IIC_Delay(20000);  //10ms 需要等10ms
	do {
		IIC_Start();
		IIC_SendByte(0xA0);
		st = IIC_WaitACK();
	} while(st == 1);
}
u8 Read_24c02(u8 add) {	//读取24c02的数据
	u8 dat, st;
	IIC_Start();
	IIC_SendByte(0xA0);
	st = IIC_WaitACK();
	if(st != 0) {//错误提示
	}
	IIC_SendByte(add);
	IIC_WaitACK();
 
	IIC_Start();
	IIC_SendByte(0xA1);
	IIC_WaitACK();
	dat = IIC_ReciveByte();
	IIC_SendNoACK();
	IIC_Stop();
	return dat;
}
 
void Save_u16(u8 add, u16 n) {
	Write_24c02(add, n/256);
	Write_24c02(add+1, n%256);
}
 
u16 Read_u16(add) {
   	u16 d;
	d = Read_24c02(add);
	d <<=8;
	d |= Read_24c02(add+1);
	return d;
}
 
 
void Save_Float(u8 add, float n) {
	 fltcom a;
	 a.t  = n; //将数据写入
	 Write_24c02(add++, a.s[0]);// 每字节存储写入的数据
	 Write_24c02(add++, a.s[1]);
	 Write_24c02(add++, a.s[2]);
	 Write_24c02(add, a.s[3]);
}
 
float Read_Float(add) {
   	fltcom a;
    //将字节的数据读取到共用体数组中
	a.s[0] = Read_u16(add++);
	a.s[1] = Read_u16(add++);
	a.s[2] = Read_u16(add++);
	a.s[3] = Read_u16(add);
	return a.t;//返回共用体float t;
}