ib technology

13

Method of Operation

The Micro RWD reader only allows full communication with EM4102 transponders if an

initial level of security has been passed. The system works by reading the tag memory,

stripping off the various parity bits to give the five-byte user memory. Bytes 1 to 4 of the

EM4102 five-byte sequence are then taken as a four byte serial number (identity code). The

most significant byte (byte 0) is ignored. The Micro RWD internal EEPROM is then checked

to see if this serial number is stored in the authorisation list located from byte 12 onwards. If

the tag serial number is matched to a serial number stored in the Micro RWD or the list is

empty then the tag has passed the validation test. If the Micro RWD has FF FF FF FF (hex)

stored at EEPROM locations 12 to 15 then the list is treated as empty and all EM4102 tags are

accepted through the validation test.

Full communication is only allowed if this initial security check has been passed (or the

Micro RWD authorisation list is empty).

Auxiliary Asynchronous Serial output

If selected, data can be automatically output from the OP0 or main TX pin as 4-bytes of data

transmitted asynchronously at 9600 baud, 8-bits, 1 stop-bit, no parity. The base data is the

least significant 4-bytes (bytes 1–4) of the EM4102 tag data or the least significant 4-bytes

(bytes 12-15) of the MCRF200/123 16-byte memory.

Auxiliary Weigand Output Protocol

If selected, data can be automatically output from the OP0 / OP1 pins as Data HIGH and Data

LOW signals according to the Weigand protocol.

The Weigand protocol (24 bit data length) can be made up of a leading even parity bit (for b0

- b11), 24 bits of data (from transponder data) and a trailing odd parity bit (for b12- b23)

creating a 26-bit output stream. The 32-bit mode has the same format except least significant

four bytes of block data are used to form the data sequence. The parity bits are included or

omitted and the byte order is reversed according to the EEPROM parameter settings.

For Example:-

Mifare block data (least significant 4 bytes):

0x04 60 22 12

(reversed byte option would use 0x12 22 60 04 as base data)

b0

b1

b2

b3

b4

b5

b6

b7

b8

b9

5v

0v

idle

START

8 bit data

STOP idle

1

0

TTL levels

Data bytes transmitted at 9600 baud, 8-bits, 1-stop bit, No parity (104 µS per bit)