rfid tag value is not machting ?..

[haroon_tech]

hi,

i am using 12khz wiegand rfid reader module , that has given wiegand data lines i.e data0 & data1 . i have written the code to read the tag when its comes in vicinity.
On the tag the numbers are "0010039334 153,12326" . i think it is EMbased tag.

what i could read in my code is for same above tag "17926604" ?

is this correct or garbage but every time it gives same value? further is there any algorithm to extract the data what i have been received?

plz can any one help me out???

thank you.

 

[rohitkhanna]

12Khz ??

There could be ... oh .... so many interface/ translation issues.

The good news is that you get a steady output. Try it with a different card, and see if you get different but steady 'garbage' also.

If so, then SOME things are working correctly, but you are probably not doing the protocols matching/ interpretation correctly.
Read the documents again, review your code again.

For e.g., are you sure its an EM card ? Can you read EM card using Wiegand ?

cheers!

 

[bigdogguru]

i am using 12khz wiegand rfid reader module , that has given wiegand data lines i.e data0 & data1 . i have written the code to read the tag when its comes in vicinity.
On the tag the numbers are "0010039334 153,12326" . i think it is EMbased tag.

what i could read in my code is for same above tag "17926604" ?

is this correct or garbage but every time it gives same value? further is there any algorithm to extract the data what i have been received?

Which Wiegand protocol? Wiegand26, Wiegand34, etc? The number represents the subsection of data in bits transmitted, for example Wiegand 26 consists of 24 bits of data and 2 bits for parity.


Wiegand is a communications protocol which can be used to transmit various types of information, including RFID, Mag Swipe, Keypad, etc. The Wiegand communications protocol essentially serves the same purpose as RS-232, RS-485, RS-422, etc.

So YES, there certainly are EM400X based 125kHz RFID tag readers which offer a WiegandXX interface, as well as RS-232, RS-485, TTL, etc.

I might also mention, most RFID readers only output data upon a successful read of the tag, incompatible tags typically result in NO data transmission.



Now concerning the "EM" based tags, these are tags with EM400X/EM410X transponders, which utilize 64-bit Manchester Encoding to contain a 40-bit ID.

For example the 40-bit ID of an EM400X/EM410X transponder tag:

4500be4a75 or 0100010100000000101111100100101001110101

A Wiegand26 transmission of the above ID, truncates it to the 24-bit Least Significant Bits (LSbs):

0100010100000000101111100100101001110101


101111100100101001110101

The above 24-bits are sometimes presented on the tag in the following format:

190,19061

101111100100101001110101

190: 10111110
19061: 0100101001110101

I should point out that the truncation of the 40-bit ID to 24-bit ID can easily result in two tags with unique IDs appearing identical once they are transmitted using the Wiegand26 protocol.

The preceding fact should be carefully considered when designing a RFID system.



Now back to your situation.

Both the numbers, "0010039334" and "153,12326" appear to represent the same 24-bit LSbs of the 40-bit ID of the tag:

0010039334: 100110010011000000100110

153: 10011001
12326: 0011000000100110

Therefore, it is likely that your Wiegand routine is incorrectly interpreting the Wiegand transmission.

Post the Wiegand routine so that it maybe examined.


BigDog

 

[haroon_tech]

ya this is my code
wiegand 26bit format (harware is Microchip ASK reader ckt )

#include<htc.h>
void display(unsigned long,unsigned char);
void read_data(void);
#include"uart_header.h"
#include"uart_header.c"
#define led RB7
#define ledd TRISB7
#define data0 RB0
#define data1 RB1

	unsigned char convert1=0;							//clear convert1
	unsigned int convert2=0;				


			//clear convert2
	unsigned char data[26];							
	
	unsigned char mode=0;								//clear mode

main()
{
	unsigned char i;						

		convert1=0;												//clear convert1
		convert2=0;												//clear convert2
		ledd=0;
		TRISB0=1;
		TRISB1=1;
		
			
		usart_init();
		
		while(1)
		{	
			
				transmitstring("\n\r");
			transmitstring("Place your tag");
			
			transmitstring("\n\r");
		while(mode==0)
			{
				i=0;
			transmitstring("\n\r");
		//	if((data0==0)||(data1==0)) 
		//	{
			//	transmitstring("\n\rwait processing....");
			//	mode=1;					
				if((data0==0)&&(data1==1))							//if data0 changes (data0 is active low)
			{
				data[i]=0;										//save that the bit received is 0
				while((data0==0)&&(data1==1));					//wait until data0 back to high logic
			}													
			else if ((data0==1)&&(data1==0))					//if data1 changes (data1 is active low)
			{
				data[i]=1;										//save that the bit received is 1
				while((data0==1)&&(data1==0));					//wait until data1 back to high logic
			}
			i+=1;												//i+1

			while(i<26)											//repeat the loop until all 26 bit data are sent (start from 0 to 25)
			{	
				while((data0==1)&&(data1==1));					//wait while data0 and data1 remain at high logic level (no changes at data0 and data1)
				if((data0==0)&&(data1==1))						//if data0 changes (data0 is active low)
				{
					data[i]=0;									//save that the bit received is 0
					while((data0==0)&&(data1==1));				//wait for data stream finish sending from RFID tag again (data0 or data1 will back to high logic)
				}
				else if ((data0==1)&&(data1==0))				//if data1 received is 0 (data1 is active low)
				{
					data[i]=1;									//save that the bit received is 1
					while((data0==1)&&(data1==0));				//wait for data stream finish sending from RFID tag again (data0 or data1 will back to high logic)
				}
				i+=1;											//i+1
			}

																
			
			for(i=0;i<8;i++)												//loop for data[0]-data[7]
			{
				convert1=(convert1<<1)|data[i+1];							//shift current data and combine with previous data, store data in convert1			}
			}
			for(i=0;i<16;i++)												//loop for data[8]-data[25]
			{
				convert2=(convert2<<1)|data[i+9];							//shift current data and combine with previous data, store data in convert2
			}
				
				display(convert1,3);							//display convert1 in 3 decimal number
											
				display(convert2,5);							//display convert2 in 5 decimal number

					led=1;
			//	__delay_ms(1);
				led=0;							
			
			
		
}
		}		
}





void display(unsigned long data,unsigned char num_dig)
{
	if(num_dig>=10)											
	{
		data=data%10000000000;
		transmit(data/1000000000+0x30);      //send to hyperteminal 
	}	
	if(num_dig>=9)
	{
		data=data%1000000000;
		transmit(data/100000000+0x30);     //send to hyperteminal
	}	
	if(num_dig>=8)
	{
		data=data%100000000;
	transmit(data/10000000+0x30);         //send to hyperteminal
	}	
	if(num_dig>=7)
	{
		data=data%10000000;
	transmit(data/1000000+0x30);         //send to hyperteminal
	}	
	if(num_dig>=6)
	{
		data=data%1000000;
		transmit(data/100000+0x30);       //send to hyperteminal
	}	
	if(num_dig>=5)
	{
		data=data%100000;
		transmit(data/10000+0x30);         //send to hyperteminal
	}	
	if(num_dig>=4)
	{
		data=data%10000;
		transmit(data/1000+0x30);        //send to hyperteminal
	}
	if(num_dig>=3)
	{
		data=data%1000;
		transmit(data/100+0x30);         //send to hyperteminal
	}
	if(num_dig>=2)
	{
		data=data%100;
		transmit(data/10+0x30);        //send to hyperteminal
	}
	if(num_dig>=1)
	{
		data=data%10;
		transmit(data+0x30);          //send to hyperteminal
	}
}

thank you valuable feedback .....