the emulator scheme
The emulator design:
1.Microcontroller, Atmega 8, 8Mhz
2.Level Converter, MAX232
3.Stabilizer, 7805 4.Crystal, 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
