WM710xx – Secure F-RAM with Gen-2 RFID

Rev. 1.4

May 2011

Page 17 of 24

SUPPORTED COMMANDS

The WM710xx supports the following Select, Inventory, and Access commands as described in the

EPCglobal class 1 generation 2 UHF RFID Specification. Please refer to the referenced document for detailed

descriptions of these commands.



Select



Query



QueryAdjust



QueryRep



ACK



NAK



Req_RN



Read



Write



Kill



Lock



Access



BlockWrite *



BlockPermalock

MAXARIAS GEN2 CUSTOM COMMAND: BLOCKWRITE

The WM710xx supports a customized version of the BLOCKWRITE command to support unique features

within the device. The BLOCKWRITE command optional feature is enabled by asserting the BLKWREN

control bit in the Control/Status register to a logic one, after which the WM710xx will require a power cycle to

initialize itself.

To support other features within the WM710xx, the BLOCKWRITE command uses the

address stored in the Working Stored Address register. The address pointer passed in the BLOCKWRITE

command is the physical address 0x3FFF (EBV formatted address = 0xF7FF), representing the same address

used for unaddressed write cycles. A single BLOCKWRITE command carries a maximum data payload of

127 words. BLOCKWRITE commands with data payloads greater than 127 words may optionally be written

to unlocked memory, however the WM710xx will not acknowledge the BLOCKWRITE command with a

success message. In this event, the host interrogator may perform one or more READ cycles to verify USER

memory data contents.

Prior to transmitting a BLOCKWRITE command, the interrogator must set the Working Stored Address

register through a standard Gen2 WRITE command. The BLOCKWRITE command is shown in Figure 17

below.

BLKWRITE

(0xC7)

Membank

(0b11)

WordPtr

(0xF7FF)

Data

(xNN × 16-bit data)

Handle

(0xHHHH)

CRC-16

(0xCCCC)

WordCnt

(0xNN)

Figure 17. Block Write Syntax

BLOCKWRITE commands do not support the auto-increment feature used for UNADDR_WRITE commands.

As such, the Working Stored Address must be manually updated by the host interrogator and will not be altered

by a BLOCKWRITE command. When using the streaming capabilities of the BLOCKWRITE command, care

should be taken to consider the logic state of the AUTOINCR control bit.

As with UNADDR_WRITE

commands, the Working Stored Address register is incremented prior to writing data to memory when

AUTOINCR=1 affecting the first USER memory address written to. Figure 18 shows an 8-word

BLOCKWRITE command with AUTOINCR=0; Figure 19 shows a BLOCKWRITE command with

AUTOINCR=1. In the respective figures, when AUTOINCR=0, data is written starting at the address defined

by the Working Stored Address register – 0x006; when AUTOINCR=1, data is written starting at the next free

address defined by the contents of the Working Stored Address incremented by one, or 0x007. It is important