WM71000-NBSD-SA Ramtron, WM71000-NBSD-SA Datasheet - Page 11

• Manufacturer Part Number: WM71000-NBSD-SA
• Description: RFID Transponder AFE Chip (No Memory) Gen-2 RFID Access
• Manufacturer: Ramtron

Specifications of WM71000-NBSD-SA

• Mounting Style: SMD/SMT
• Package / Case: SOIC-8

Rev. 1.3
Apr. 2011
Upon power up, WM710xx‟s control logic reads the Control/Status word out of memory and configures itself
accordingly. User applications may change the Control Word as needed providing the register has not been
permanently locked. The Control/Status word may be read by the application at any time.
Register Locking: The LOCK and PERMALOCK control bits are implemented in a similar manner as locking
bits used for Gen2 memory bank locking with the exception that the lock control bits are incorporated into the
register they are locking. As such, attention needs to be placed on how the contents of the Control/Status word
are written when the register is not completely unlocked.
LOCK
Table 4: Control/Status Word Locking
Block Write Enable: The BLKWREN control bit enables usage of the WM710xx custom command
BLOCKWRITE. The BLKWREN parameter is internally updated during power-on WM710xx initialization.
In the event the host application toggles the state of BLKWREN, a WM710xx power cycle is required to reflect
the change.
Block Size: The 3 BLKSIZ[2:0] control bits adjust the USER memory block sizes as shown in Table 5:. This
provides the RFID application the ultimate flexibility in determining a balance between the USER memory
requirements and the granularity of the number of USER memory words per block. For the WM71016, the
larger the granularity of the block size, the greater amount of available USER memory; block size has no effect
on WM71004 or WM71008 memory. The effect of the block size on available USER memory is shown in
Table 1. The total number of USER memory words available as a function of the block size is shown in Table 5
below. It is of utmost importance that the 3-bit block size is not modified once set, which would result in
corruption of block permalock status bits.
Table 5: Available USER Memory
Wrap Status: The WRPSTAT status bit is asserted to a logic one when the following conditions are true:
The WRPSTAT can be cleared by the RFID interrogator by writing a logic zero to the WRPSTAT bit.
0
0
1
1
(a) WRPEN=1, AUTOINCR=1 and AUTOLOCK=0,
(b) The contents of the Working Stored Address register address the last USER memory location, and
(c) An unaddressed WRITE command is received.
Memory
16k
16k
16k
16k
16k
16k
16k
16k
4k
8k
PERMA-
LOCK
0
1
0
1
Description
Register unlocked. All control bits, including the LOCK and PERMALOCK bits can
be written to from the OPEN or SECURED states.
Register permanently unlocked. All control bits can be written from the OPEN or
SECURED states. The LOCK and PERMALOCK bits must be set to logic values 0
and 1 respectively when writing the Control/Status word.
Register locked. All control bits can be written to only from the SECURED state.
The register cannot be written to in the OPEN state. The LOCK and PERMALOCK
bits must be set to logic values 1 and 0 respectively when writing the Control/Status
word.
Register permanently locked. The register cannot be written in any circumstance.
BLKSIZ
xxx
xxx
000
001
010
011
100
101
110
110
Words/Block
128
16
32
64
x
x
1
2
4
8
WM710xx – Secure F-RAM with Gen-2 RFID
Free USER Memory
(words)
230
486
931
963
979
987
991
993
993
993
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