PCF7936AS datasheet(11/32 Pages) PHILIPS

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NXP Semiconductors

Product Specification

Security Transponder (HITAG2)

PCF7936AS

2010 May 04

CONFIDENTIAL

READ_PAGE

READ_PAGE_INV

WRITE_PAGE

LF Field

Power On Reset

AUTHORIZED

START_AUTH

Error

HALT

READ ONLY

WAIT

HALT

time-out (tWAIT,SA)

Read Only = enabled

Figure 7. Transponder State Diagram

7.2 Transponder State Diagram

Device operation is controlled by commands issued from

the basestation, see Figure 7.

After a LF Field Power-On Reset condition the circuitry is

reset and the transponder is initialized, which causes the

device to enter the WAIT state.

If one of the Read Only modes is enabled, the device will

enter READ ONLY state after the specified time-out

(tWAIT,SA), if no command is being issued.

To authenticate the transponder and to access the

Transponder Memory for read and write the AUTHORIZED

state has to be entered, by means of a START_AUTH

command and successful completion of the authentication

sequence. Subsequent memory read and write operations

may be executed.

Operation of the transponder commands depend on the

device configuration (Password or Cipher Mode).

If the device is forced into HALT state, by means of the

HALT command, the transponder circuitry is muted.

A violation of the command sequence coding or command

timing in any state causes an error condition, which causes

the device to enter WAIT state and to reset the time-out

(tWAIT,SA).

7.2.1

WAIT State

WAIT

state

general

memory

access

denied.

Commands may be issued to start device authentication, in

order to enter the AUTHORIZED state, see Table 2.

Table 2. Command Set in WAIT State

NAME

COMMAND, CMD

CM4

CM3

CM2

CM1

CM0

Reserved

START_AUTH

Note

1. This command is reserved for future use and subject to

change without notice. The actual implementation

causes the device to generate an error condition and to

enter the WAIT state, if this command is being issued.

Upon entering the WAIT state the time-out (tWAIT,SA) is

reset. In case tWAIT,SA is allowed to time-out, the device

enters READ ONLY state, if one of the Read Only modes is

enabled. In case a START_AUTH command is issued,

device authentication is triggered and the READ ONLY

state is not entered. At least the first two bits of

START_AUTH need to be recognized by the device within

the time-out period specified by tWAIT,SA.

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