WM71016 Ramtron, WM71016 Datasheet - Page 6

• Manufacturer Part Number: WM71016
• Description: (WM71004 - WM71016) 4/8/16Kbit Secure F-RAM Memory
• Manufacturer: Ramtron

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Rev. 1.4
May 2011
INTERROGATOR
RESERVED: KILL Password:
The kill password provides a mechanism to permanently disable the WM710xx RFID from responding to any
and all Gen2 interrogator commands. The mandatory KILL command can be issued by a RFID interrogator in
either the OPEN or SECURED states. The WM710xx is permanently killed through a four-instruction
sequence of REQRN and KILL commands as detailed in the Gen2 standard. The KILL password is a 32-bit
value stored as 2 16-bit data words in reserved memory. The most significant KILL password is stored in
reserved memory bank address 0x00 with the least significant word stored in reserved memory bank address
0x01. The kill function can be permanently disabled by setting both KILL password words to 0x0000, and
permanently locking the KILL password in the reserved memory bank. Once the kill password has been set, it
should be permanently locked using the LOCK command. The WM710xx is shipped from the factory with the
kill password memory unlocked.
RESERVED: ACCESS Password:
The access password provides a security mechanism to prevent unauthorized RFID interrogators from writing
to WM710xx memory. Non-zero access passwords require the WM710xx be placed in the SECURED state
prior to writing to it. This is accomplished through four consecutive REQRN and ACCESS commands as
described in the Gen2 standard. An access password with a value of zero requires no authentication prior to
writing to WM710xx memory. The ACCESS password is a 32-bit value stored as 2 16-bit data words in
reserved memory. The most significant ACCESS password is stored in reserved memory bank address 0x02
with the least significant word stored in reserved memory bank address 0x03. Once the access password has
been set, it should be permanently locked using the LOCK command. The WM710xx is shipped from the
factory with the access password memory unlocked.
EPC Memory Bank:
The EPC memory bank accommodates 8 words: 1 protocol control (PC) word, a 6-word (96-bit) memory space
for an EPC identifier, and a 1-word CRC. The CRC word is calculated as part of the WM710xx power-on
initialization routine and written into the EPC memory bank address 0x00. The PC and 6-word EPC identifier
are completely programmable. The Protocol Control field is shown in Figure 4.
Figure 3. Gen2 Memory Write Cycle Comparison: F-RAM vs. EEPROM Memories
TAG
MaxArias Write Cycle
EEPROM-based Write Cycle
SELECT
(385u)
QURY
(240u)
(53u)
RN
(175u)
ACK
(228u)
EPC
4ms
REQRN
(345u)
HANDLE
WM710xx – Secure F-RAM with Gen-2 RFID
(78u)
REQRN
(345u)
RN16
(78u)
WRITE
(495u)
WR_OK
(80u)
Page 6 of 24
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