WM72016 – Secure F-RAM with Gen-2 RFID and Serial Port

Rev. 1.4

May 2011

Page 5 of 32

DSPI

Address

Gen-2

Memory Bank

Gen-2

Address

Word

Pointer

(EBV8)

Description

…

…

…

…

0x3DA

USER

0x3C6

0x8746

0x3DB

USER

0x3C7

0x8747

16k Memory: END

(BLK_SIZE = 2 words/block)

0x3DC

USER

0x3C8

0x8748

0x3DD

USER

0x3C9

0x8749

0x3DE

USER

0x3CA

0x874A

…

…

…

…

0x3EA

USER

0x3D6

0x8756

0x3EB

USER

0x3D7

0x8757

16k Memory: END

(BLK_SIZE = 4 words/block)

0x3EC

USER

0x3D8

0x8758

0x3ED

USER

0x3D9

0x8759

0x3EE

USER

0x3DA

0x875A

…

…

…

…

0x3F3

USER

0x3DF

0x875F

16k Memory: END

(BLK_SIZE = 8 words/block)

0x3F4

USER

0x3E0

0x8760

0x3F5

USER

0x3E1

0x8761

0x3F6

USER

0x3E2

0x8762

0x3F7

USER

0x3E3

0x8763

16k Memory: END

(BLK_SIZE = 16 words/block)

0x3F8

USER

0x3E4

0x8764

0x3F9

USER

0x3E5

0x8765

16k Memory: END

(BLK_SIZE = 32 words/block)

0x3FA

USER

0x3E6

0x8766

0x3FB

USER

0x3E7

0x8767

(BLK_SIZE > 32 words/block)

0x3FC

USER

0x3E8

0x8768

RESERVED

0x3FD

USER

0x3E9

0x8769

RESERVED

0x3FE

USER

0x3EA

0x876A

RESERVED

0x3FF

USER

0x3EB

0x876B

RESERVED

NOTE: When accessing the memory through the DSPI serial port, care must be taken to ensure that reserved

memory required to store critical parameters for the operation of the device is not altered.

GEN2 WM72016 MEMORY BANKS

The RFID memory banks reside in Ramtron‟s non-volatile F-RAM memory. F-RAM brings many benefits to

the WM72016. The first benefit is the size of the memory itself – 16k-bit, most of which is available in the

USER memory bank.

F-RAM‟s impact on the Gen2 protocol is most dramatically seen when writing to

WM72016 memory. Unlike EEPROM memory, no charge pump or memory soak time is required to write to

WM72016 memory resulting in zero time and zero power penalties.

The write cycle is completed

immediately, allowing an interrogator to continue writing additional data to memory with no time penalty

incurred due to the memory itself. A comparison between F-RAM and EEPROM memories is shown in Figure

3. The figure shows the minimum number of Gen2 instructions required to perform a SELECT, INVENTORY,

and ACCESS sequence of commands to write a data word to memory. The same interrogator command

sequence is transmitted to the WM72016 and an EEPROM-based RFID. The effect of the EEPROM time

penalty is shown within the context of the protocol.