EM4170

Copyright

 2002, EM Microelectronic-Marin SA

7

www.emmicroelectronic.com

Authentication

In this mode the chip first receives the 56 bits of random number followed by a certain number of divergency bits that the

reader should send as "0" followed by 28 Bits of cipher_1 (f(RN)) as authentication of the lock. The chip decides if the

authentication is accepted. In this case the EM4170 sends a header (12 Manchester coded '1's followed by 4 Manchester

coded '0's). Next 20 Bits of cipher_2 (g(RN)) are sent. Else it sends a single NAK. Upon completion of this command the

EM4170 returns to Standby Mode.

Begin

Receive

f(RN)

(28 Bits)

Divergency

Send

g(RN)

(20 Bits)

End

Y

N

Send

header

Send

NAK

Receive

RN

(56 Bits)

f(RN)

valid?

Fig. 7

OUTPUT

INPUT

RM

RN

f(RN)

g(RN)

LIW

Header

LIW

Command

“0000000”

Fig. 8

Write Word

The Write Word command is followed by the address and data. The address consists of a 5 bit block containing 4 data bits

and 1 even parity. The data consists of 4 times 5 bit blocks, each block consisting of 4 data bits and 1 associated even

parity bit. One additional block consists of 4 column parity bits and a trailing zero (refer to fig 10).

Address

A3 A2 A1 A0 Padd

Data

D15 D14 D13 D12 P3 D11 D10 D09 D07 P2 D07 D06 D05 D04 P1 D03 D02 D01 D00 P0 PC3 PC2 CP1 PC0 "0"

Fig. 9

First bit received