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

Rev. 1.4

May 2011

Page 13 of 32

Working Stored

Address Pointer

Gen-2 Memory

Bank

Gen-2 Address

Description

RESERVED

0x000 - 0X003

RESERVED - passwords

EPC

0x000 - 0x009

EPC

SERVICE

0x00A

RESERVED

SERVICE

0x00B

RESERVED

TID

0x000 - 0x003

TID

USER

0x000

RESERVED

USER

0x001

RFU

USER

0x002

Control/Status Register

USER

0x003

Working Stored Address Register: 0x0006

USER

0x004

USER

0x005



USER

0x006

USER Memory - START

USER

0x007

USER

0x008

USER

…

…

USER

USER Memory - END

Figure 12. USER Memory Bank: Working Stored Address Register

The syntax for an unaddressed write command is shown in Figure 13 below.

All protocol requirements

governing implementation of a WRITE command also apply to the UNADDR_WRITE command.

WRITE

(0xC3)

Membank

(0b11)

WordPtr

(0xF7FF)

16-bit Data (cover-coded)

(0xNNNN)

Handle

(0xHHHH)

CRC-16

(0xCCCC)

Figure 13. Unaddressed Write Syntax

Upon reception of a valid UNADDR_WRITE command, the WM72016 examines the state of the AUTOINCR

control bit:

AUTOINCR=0: The 16-bit data word cover-coded in the unaddressed write instruction is written to the

memory address stored in the Working Stored Address register. The contents of the Working Stored

Address register remain unaltered. To avoid the memory being over-written, the Working Stored Address

register must be manually updated.

AUTOINCR=1: The Working Stored Address register is incremented by one, followed by the 16-bit data

word being written to memory. The contents of the Working Stored Address register will reflect the

memory address just written to.

A single unaddressed write cycle is shown in Figure 14 with the

AUTOINCR control bit set to a logic one. The Working Stored Address has an initial value of 0x0006 as

shown in Figure 12. An unaddressed write cycle (with AUTOINCR=1) increments the address pointer to

to USER memory address 0x007. Figure 15 depicts an additional seven discrete unaddressed write cycles

(REQRN command for cover-coding not shown). Prior to unaddressed write commands, the Working

unaddressed write cycle.

In this manner, the RFID interrogator does not have to read the memory

contents to discern the next available memory location. This substantially reduces the time required

in the RF field yielding greater throughput of a population of tags.

The Working Stored Address pointer will be factory-initialized to the start of USER memory then

managed by the memory controller or the host application as required.