At first that's my first big post and please excuse my bad english :)

In scanwidgets Thread about an passiv RFID emulator i have met Dlinyj. He has told me of
this emulator. First i have build Michal Krummnickels( emulator on a test PCB. After that i had decided that i need a life connection to the computer to emulate fast and easy RFID tags. It can emulate/simulate 125khz EM4001 compatible RFID tags. I have written a C program for the Microcontroller and for the Computer. 
my finished emulator
The scheme:

the emulator scheme
The emulator design:

1.Microcontroller, Atmega 8, 8Mhz
2.Level Converter, MAX232
3.Stabilizer, 7805 4.Cryst
al, 8Mhz
5.Control LED
6.Power LED
7.Power connection
8.Coil connection
9.Reset Bottom
10.ISP connection
11.RS232 connector
The Program:

You can download the Program here. Please excuse me that i have comment the programs in german. The Computer sends the finish calculated ID over the RS232 connection to the Microcontroller. The Microcontroller receives the ID and emulate it. The Baud rate is 9600bd.

How to compile the Computer program:
$ cd /your/folder/
$ cc -o rpv11 rpv11.c
$ sudo ./rpv11
(tested with Ubuntu 8.40)

I have compiled the Microcontroller program with AVR-GCC.
I have used
Avr Slax to compile it.

How to compile the Microcontroller program:
$ cd /your/folder/
$ make all

The Manchester coding:

There is always a transition from ON to OFF or from OFF to ON in the middle of bit period. At the transition from logic bit “1” to logic bit “0” or logic bit “0” to logic bit “1” the phase change. Value high of data stream presented below modulator switch OFF, low represents switch ON

the modulation at the coil of the emulator

the modulation at the coil of the reader

As you can see at this pictures a Bit is 512µs long. You can see clearly the ON and the OFF in a Bit period. The EM4001 transmits a 64bit long ID. An ID is transmitted in 32.768ms.

If you have some questions or need some help just ask.
If you need more information about the manchester coding is here the EM4001 datasheet.

More pictures


 © 2010 • ImpressumÜber mich