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White Electronic Designs Corporation (602) 437-1520 www.whiteedc.com
White Electronic Designs
W78M32V-XBX
April 2006
Rev. 3
White Electronic Designs Corp. reserves the right to change products or specications without notice.
PPB LOCK BIT SET COMMAND
The PPB Lock Bit Set command is used to set the PPB
Lock bit if it is cleared either at reset or if the Password
Unlock command was successfully executed. There is no
PPB Lock Bit Clear command.
Once the PPB Lock Bit is set, it cannot be cleared unless the
device is taken through a power-on clear or the Password
Unlock command is executed. Upon setting the PPB Lock
Bit, the PPBs are latched into the DYBs. If the Password
Mode Locking Bit is set, the PPB Lock Bit status is reected
as set, even after a power-on reset cycle. Exiting the PPB
Lock Bit Set command is accomplished by writing the Read/
Reset command (only in the Persistent Protection Mode).
DYB WRITE COMMAND
The DYB Write command is used to set or clear a DYB for
a given sector. The high order address bits
(A22–A12) are issued at the same time as the code 01h or
00h on DQ7-DQ0. All other DQ data bus pins are ignored
during the data write cycle. The DYBs are modiable at
any time, regardless of the state of the PPB or PPB Lock
Bit. The DYBs are cleared at power-up or hardware reset.
Exiting the DYB Write command is accomplished by writing
the Read/Reset command.
PASSWORD UNLOCK COMMAND
The Password Unlock command is used to clear the PPB
Lock Bit so that the PPBs can be unlocked for modication,
thereby allowing the PPBs to become accessible for
modication. The exact password must be entered in order
for the unlocking function to occur. This command cannot
be issued any faster than 2 μs at a time to prevent a hacker
from running through all 64-bit combinations in an attempt
to correctly match a password. If the command is issued
before the 2 μs execution window for each portion of the
unlock, the command will be ignored.
Once the Password Unlock command is entered, the
RY/BY# indicates that the device is busy. Approximately 1
μs is required for each portion of the unlock. Once the rst
portion of the password unlock completes (RY/BY# is not
low or DQ6 does not toggle when read), the next part of the
password is written. The system must thus monitor RY/BY#
or the status bits to conrm when to write the next portion
of the password. Seven cycles are required to successfully
clear the PPB Lock Bit.
PPB PROGRAM COMMAND
The PPB Program command is used to program, or set,
a given PPB. Each PPB is individually programmed (but
is bulk erased with the other PPBs). The specic sector
address (A22–A12) are written at the same time as the
program command 60h with A6 = 0. If the PPB Lock Bit is
set and the corresponding PPB is set for the sector, the PPB
Program command will not execute and the command will
time-out without programming the PPB.
After programming a PPB, two additional cycles are needed
to determine whether the PPB has been programmed with
margin. If the PPB has been programmed without margin,
the program command should be reissued to improve the
program margin. Also note that the total number of PPB
program/erase cycles is limited to 100 cycles. Cycling the
PPBs beyond 100 cycles is not guaranteed.
The PPB Program command does not follow the Embedded
Program algorithm.
ALL PPB ERASE COMMAND
The All PPB Erase command is used to erase all PPBs in
bulk. There is no means for individually erasing a specic
PPB. Unlike the PPB program, no specic sector address
is required. However, when the PPB erase command
is written all Sector PPBs are erased in parallel. If the
PPB Lock Bit is set the ALL PPB Erase command will not
execute and the command will time-out without erasing the
PPBs. After erasing the PPBs, two additional cycles are
needed to determine whether the PPB has been erased
with margin. If the PPBs has been erased without margin,
the erase command should be reissued to improve the
program margin.
It is the responsibility of the user to preprogram all PPBs
prior to issuing the All PPB Erase command. If the user
attempts to erase a cleared PPB, over-erasure may occur
making it difcult to program the PPB at a later time. Also
note that the total number of PPB program/erase cycles is
limited to 100 cycles. Cycling the PPBs beyond 100 cycles
is not guaranteed.