WM710xx – Secure F-RAM with Gen-2 RFID
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 4. EPC Protocol Control Word
The 5 most significant bits of the PC indicates the size of the EPC identifier in words – for a 96-bit (6-word)
EPC identifier, the PC should be programmed to 0b0011_0xxx_xxxx_xxxx. The LEN parameter of the PC
word may not be greater than 0b00110 – a LEN parameter of 0b00000 has an EPC identifier length of zero
words resulting in only the PC and CRC words when WM710xx is acknowledged. The UMI bit (User
Memory Identifier) is asserted to a logic one by WM710xx and mapped to bit 10 of the PC word. In the event
the host writes a logic zero to the UMI bit, the memory location will be written with a logic zero, however the
backscattered EPC identifier will assert the UMI bit to a logic one which is also used in the calculation of the
CRC. WM710xx does not support extended protocol control and should be written with a logic zero. PC word
bits 8 down to 0 of the PC word are factory-initialized to zero. The WM710xx is shipped from the factory with
the EPC memory bank unlocked.
TID Memory Bank:
The TID memory bank consists of 4 words (64 bits), and is defined as shown in Table 2:. The TID memory
bank is permanently locked at the factory and obeys the ISO/IEC 15963 numbering convention.
Table 2: TID memory Bank Fields
Bit Field
00
h
– 07
h
08
h
– 0F
h
10
h
– 3F
h
Value
(hex)
xE0
TBD
Unique
Description
15963 class-identifier value
Manufacturer identifier
48-bit unique identifier
USER Memory Bank:
The USER memory bank comprises two special-function control words, factory-reserved words, and up to 993
available memory locations. Refer to Table 1: for detail on the WM710xx memory structure. The USER
memory bank may be completely locked through the LOCK command. WM710xx also supports the
BLOCKPERMALOCK command providing the ability to lock contiguous words of USER memory, with word
block sizes as small as a single word up to a maximum block size of 128 words.
Rev. 1.2
Sept. 2010
Page 6 of 17
RAMTRON [ RAMTRON INTERNATIONAL CORPORATION ]
