//THIS CODE WAS DESIGNED TO DEMONSTRATE HOW THE FM24C04/FM24C04A SERIAL FRAM COULD 
//BE INTERFACED TO THE 8051 MICROCONTROLLER. THE INTERFACE USES 2 LINES 
//FROM PORT 2 (P2.7 AND P2.6) TO COMMUNICATE. 
//THE CODE SHOWN DEMONSTRATES A 'RANDOM READ' AND 'BYTE WRITE'. THE OTHER *
//MODES OF OPERATION CAN BE CREATED BY EXPANDING UPON THESE ROUTINES.
//深圳市華胄科技有限公司
//the first date writed:2003-11-20
//=============================
#include<reg52.h>
#include<intrins.h>
#define uchar unsigned char
#define uint unsigned int
#define IIC_READ 0XA1    //定義讀指令
#define IIC_WRITE 0XA0   //定義寫指令
#define NOP _nop_()
//==============================
uchar idata buff[32];	//save the byte read out  form iic device in test operation
uchar idata readbuff[32];//測試數組，暫存寫入讀出數據
//uchar writebuff[32];
//===============================
sbit SDA=P2^7;	//THE SDA BIT IS PORT 2 BIT 7
sbit SCL=P2^6;	//THE SCL BIT IS PORT 2 BIT 6
sbit WP=P2^5;
sbit test=P1^0;
//===============================
//define a bit_operation byte to use in shift operation
//use this mode can achieve high operation speed 
uchar bdata bbyte;//定義位操作用數組，采用此方法可提高位操作速度
sbit a0=bbyte^0;
sbit a1=bbyte^1;
sbit a2=bbyte^2;
sbit a3=bbyte^3;
sbit a4=bbyte^4;
sbit a5=bbyte^5;
sbit a6=bbyte^6;
sbit a7=bbyte^7;
//========================================
bit IFACK;	//record the SDA state to confirn if ACK has happened 
bit NO_ACK;	//no ack flag
bit BUS_FAULT;	//bus fault flag
//========================================
//FUNCTION:ROUTES TO PROVIDE A START SIGNAL
void start(void)
{
	SCL=0;SDA=1;SCL=1;SDA=0;SCL=0;
}
//=======================================
//FUNCTION:ROUTES TO PROVIDE A STOP SIGNAL
void stop(void)
{
	SCL=0;SDA=0;SCL=1;SDA=1;SCL=0;
}
//=====================================
//FUNCTION:ROUTES TO PROVIDE ACK SINGAL
void ack(void)
{
	SCL=0;SDA=0;SCL=1;SCL=0;
}
//=====================================
//FUNCTION:ROUTES TO RELEASE THE SDA TO RECEIVE A ACK SIGNAL 
//	             OR TO PROVIDE A NO_ACK SIGNAL
//type=1等待應答信號
//type=0 產生無應答信號
void nack(uchar type)
{
	SCL=0;SDA=1;SCL=1;IFACK=SDA; SCL=0;
	if(type)
	{
		if(IFACK)//如果無應答信號，則置標志位NO_ACK,程序中止
		{	
			NO_ACK=1;//用戶可以加入自己的異常處理程序
			//while(1);
		}
		else NO_ACK=0;
	}
}
//=======================================================
//FUNCTION:THE IIC DEVICE SHIFT OUT A BYTE  TO THE MASTER
uchar  inbyte(void) {//從IIC器件中讀出數據
	SDA=1;
	SCL=1;a7=SDA;SCL=0;
	SCL=1;a6=SDA;SCL=0;
	SCL=1;a5=SDA;SCL=0;
	SCL=1;a4=SDA;SCL=0;
	SCL=1;a3=SDA;SCL=0;
	SCL=1;a2=SDA;SCL=0;
	SCL=1;a1=SDA;SCL=0;
	SCL=1;a0=SDA;SCL=0;
	return(bbyte);
}
//=======================================================
//FUNCTION:THE IIC DEVICE SHIFT IN A BYTE FROM THE MASTER 
void outbyte(uchar outdata) {//將數據寫放IIC器件
	bbyte=outdata;
	SDA=a7;SCL=1;SCL=0;
	SDA=a6;SCL=1;SCL=0;
	SDA=a5;SCL=1;SCL=0;
	SDA=a4;SCL=1;SCL=0;
	SDA=a3;SCL=1;SCL=0;
	SDA=a2;SCL=1;SCL=0;
	SDA=a1;SCL=1;SCL=0;
	SDA=a0;SCL=1;SCL=0;
}
//======================================================
//FUNCTION:BYTE WRITE.  'add'     THE WRITE ADDRESS, 'wbyte'   THE DATA WANT TO WRITE
void writebyte(uint add,uchar wbyte)//add為寫入地址，wbyte為寫入數據
{
	uchar temph,templ;
	temph=(uchar)(add/256);
	templ=(uchar)(add%256);
	outbyte(IIC_WRITE);	        //寫命令
	nack(1);			        //等待應答
	outbyte(temph);		        //寫地址
	nack(1);			        //等待應答
	outbyte(templ);		        //寫地址
	nack(1);
	outbyte(wbyte);			    //寫數據
	nack(1);			        //等待應答
	stop();				        //停止信號
}
//=====================================================
//FUNCTION:RANDOM READ.'add' IS THE ADDRESS WANT TO READ
uchar readbyte (uint add)//add為讀地址
{
	uchar temp,temph,templ;	
	temph=(uchar)(add/256);
	templ=(uchar)(add%256);
	start();			        //開始信號
	outbyte(IIC_WRITE);			//寫命令
	nack(1);			        //等待應答
	outbyte(temph);		        //寫地址
	nack(1);			        //等待應答
	outbyte(templ);		        //寫地址
	nack(1);
	start();			        //開始信號
	outbyte(IIC_READ);			//讀命令
	nack(1);			        //等待應答
	temp=inbyte();			    //讀數據
	nack(0);			        //無應答
	stop();				        //停止信號
	return(temp);
}
//=================================================
//連寫函數
//add為讀起始地址，ptr數據保存指針,writelen為寫入數據長度
void writebyteseq(uint add,uchar *ptr,uint writelen)
{
	//uchar temp;
	uchar temph,templ;
	uint i;
	temph=(uchar)(add/256);
	templ=(uchar)(add%256);
	start(); 		
	outbyte(IIC_WRITE);		
	nack(1);		
	outbyte(temph);
	nack(1);
	outbyte(templ);
	nack(1);
	for(i=0;i<writelen;i++)
	{
		outbyte(*(ptr+i));
		nack(1);
	}
	stop();	
}
//=================================================
//連讀函數
//add為讀起始地址，ptr數據保存指針,writelen為讀出數據長度
void readbyteseq(uint add,uchar *ptr,uint readlen)
{
	uchar temph,templ;
	uint i;
	temph=(uchar)(add/256);
	templ=(uchar)(add%256);
	start();
	outbyte(IIC_WRITE);
	nack(1);
	outbyte(temph);
	nack(1);
	outbyte(templ);
	nack(1);
	start();
	outbyte(IIC_READ);
	nack(1);
	for(i=0;i<readlen-1;i++)
	{
		*(ptr+i)=inbyte();
		ack();
		
	}
	*(ptr+readlen-1)=inbyte();
	nack(0);
	stop();
}
//=======================================================
//THIS IS A TEST OPERATION 
void main(void)
{
	uchar i;
	WP=0;
	while(1)
	{
		for(i=0;i<32;i++) readbuff[i]=0;
		writebyteseq(0, readbuff, 32);
		for(i=0;i<32;i++) readbuff[i]=0;
		readbyteseq(0,readbuff,32);
		//for(i=0;i<32;i++)
			//writebyte(300+i,i);
		for(i=0;i<32;i++) 
			buff[i]=readbyte(i);
		i=0;	
	}
}