em4100.c

通用曼彻斯特RFID读卡程序

#include<EM4100.h>
#include<intrins.h>


uchar counter=0;
bit temp1;
bit temp2;
bit sys_flag=0;
bit start_flag=0;
bit RX_flag=0;
bit _data;
bit Ready=0;
ulong card_sn=0;
uchar col_check[4];//column pority
uchar row;
uchar col;
uchar even=0;  //row pority

uchar TH0_TEMP;
uchar TL0_TEMP;

/* Initial of timer0 */
void EM4100_INI()//24MHZ
{
	TMOD=0x21;
	//TH0=0xfe;//need modify using different crastal
	//need modify using different crastal
	//TL0=0x17;//need modify using different crastal 24M
	//TL0=0x1a;	   //12M
//	TH0=0xfe;		 //need modify using different crastal
//	TL0=0x18;		 //need modify using different crastal
//	TH0=TH0_TEMP=0xff;
//	TL0=TL0_TEMP=0x19;
	TH0=TH0_TEMP=0xfe;
	TL0=TL0_TEMP=0x40;

	ET0=1;
	TR0=1;
	EA=1;
}

/* return the statue */
uchar EM4100_READY()
{
	return (uchar)Ready;
}

/* return the card number */
ulong Get_SN()
{
	ulong i=card_sn;
	card_sn=0;
	Ready=0;
	return i;
}

//Enable the timer
void Get_Enable()
{
	ET0=1;
}

//exactitude 256us timer isr
void Timer0() interrupt 1
{	
//	uchar a,b,c,d,e,f;
	TH0=TH0_TEMP;
	_nop_();
	TL0=TL0_TEMP;		   //8M
/*	a=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	b=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	c=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	d=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	f=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	b=(uchar)RF_IN;
	_nop_();_nop_();_nop_();_nop_();//_nop_();_nop_();_nop_();_nop_();_nop_();
	a=a+b+c+d+e+f;
	if(a>2)temp2=1;   //sample
	else temp2=0; */
	temp2=RF_IN;
	if(RX_flag)	//receive data
	{		
		if(start_flag)
		{
			start_flag=0;
			temp1=temp2;
		}
		else 
		{
			start_flag=1;
			counter++;		 //data volumn
			if(temp1==1&&temp2==0)_data=1;//flop  data "1"
			else if(temp1==0&&temp2==1)_data=0;	//flip	  data "0"
			else  //error 
			{
				RX_flag=0; //turn to normal state
				start_flag=1;
				counter=0;
				card_sn=0; row=col=0;
				return;
			}
			if(counter>10)   //receive the last three bytes
			{
	  			/* check the data */
				if(counter==25||counter==30||counter==35||counter==40||counter==45||counter==50||counter==55)
				{ 
					if(temp2)even++;
					if((even&0x01)!=0)even=0;
					else  //error
					{
						col_check[0]=col_check[1]=col_check[2]=col_check[3]=0;
						row=col=0;	  
						RX_flag=0; //turn to normal state
						start_flag=1;
						counter=0;
						card_sn=0;
						return;
					}
				}
				else  //receive the data
				{
					if(col==3){col=0;row++;}
					else col++;
					if(counter<=50)//receive valid data
					{
						card_sn<<=1;
						card_sn+=(ulong)_data;
					}
					if(_data){even++;col_check[col]++;}	//check
				}
			}
			if(counter==54)	//transmit complet! do not care the last bit "0"
			{
				if((col_check[0]&0x01)&&(col_check[0]&0x01)&&(col_check[0]&0x01)&&(col_check[0]&0x01))
					col_check[0]=col_check[1]=col_check[2]=col_check[3]=0;		//check right
				else		  //check error
				{ 			
					col_check[0]=col_check[1]=col_check[2]=col_check[3]=0;
					row=col=0;	  
					RX_flag=0; //turn to normal state
					start_flag=1;
					counter=0;
					card_sn=0;
					return;
				}
				Ready=1;	//data are ready
				counter=0;	//turn to normal state
				RX_flag=0;
				start_flag=1;
				sys_flag=0;
				ET0=0; row=col=0;
			}
		}		
	}
	else   //finding the header
	{
 
		if(sys_flag)
			if(temp2==0)//flop
			{
				counter++;
				sys_flag=0;
			}
			else 
			{
				sys_flag=1;	//attention!!! must be a started of flop
				counter=0;
			}
		else if(temp2==1)sys_flag=1;
		if(counter==9)				//the header is over
		{
			RX_flag=1;		 //enable receive data
			start_flag=1;
			counter=0;
		}
	}
}