Verify. Writing the Read/Reset command returns the
device back to normal operation.
The SecSi Sector Protection Bit Program command is
permitted if the SecSi sector is enabled.
Password Protection Mode Locking Bit
Program Command
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 exe-
cuted. There is no PPB Lock Bit Clear command.
Once the PPB Lock Bit is set, it cannot be cleared un-
less 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 reflected as set, even after a
power-on reset cycle. Exiting the PPB Lock Bit Set
command is accomplished by writing the Read/Reset
command.
The Password Protection Mode Locking Bit Program
Command programs the Password Protection Mode
Locking Bit, which prevents further verifies or updates
to the Password. Once programmed, the Password
Protection Mode Locking Bit cannot be erased! If the
Password Protection Mode Locking Bit is verified as
program without margin, the Password Protection
Mode Locking Bit Program command can be executed
to improve the program margin. Once the Password
Protection Mode Locking Bit is programmed, the Per-
sistent Sector Protection Locking Bit program circuitry
is disabled, thereby forcing the device to remain in the
Password Protection mode. Exiting the Mode Locking
Bit Program command is accomplished by writing the
Read/Reset command.
The PPB Lock Bit Set command is permitted if the
SecSi sector is enabled.
DYB Write Command
The Password Protection Mode Locking Bit Program
command is permitted if the SecSi sector is enabled.
The DYB Write command is used to set or clear a DYB
for a given sector. The high order address bits
(A18–A11) 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
modifiable 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.
Persistent Sector Protection Mode
Locking Bit Program Command
The Persistent Sector Protection Mode Locking Bit
Program Command programs the Persistent Sector
Protection Mode Locking Bit, which prevents the Pass-
word Mode Locking Bit from ever being programmed.
If the Persistent Sector Protection Mode Locking Bit is
verified as programmed without margin, the Persistent
Sector Protection Mode Locking Bit Program Com-
mand should be reissued to improve program margin.
By disabling the program circuitry of the Password
Mode Locking Bit, the device is forced to remain in the
Persistent Sector Protection mode of operation, once
this bit is set. Exiting the Persistent Protection Mode
Locking Bit Program command is accomplished by
writing the Read/Reset command.
The DYB Write command is permitted if the SecSi
sector is enabled.
Password Unlock Command
The Password Unlock command is used to clear the
PPB Lock Bit so that the PPBs can be unlocked for
modification, thereby allowing the PPBs to become ac-
cessible for modification. 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 the
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.
The Persistent Sector Protection Mode Locking Bit
Program command is permitted if the SecSi sector is
enabled.
SecSi Sector Protection Bit Program
Command
The SecSi Sector Protection Bit Program Command
programs the SecSi Sector Protection Bit, which pre-
vents the SecSi sector memory from being cleared. If
the SecSi Sector Protection Bit is verified as pro-
grammed without margin, the SecSi Sector Protection
Bit Program Command should be reissued to improve
program margin. Exiting the VCC-level SecSi Sector
Protection Bit Program Command is accomplished by
writing the Read/Reset command.
The Password Unlock function is accomplished by
writing Password Unlock command and data to the
device to perform the clearing of the PPB Lock Bit.
The password is 64 bits long, so the user must write
the Password Unlock command 2 times for a x32 bit
data bus and 4 times for a x16 data bus. A0 is used to
determine whether the 32 bit data quantity is used to
match the upper 32 bits or lower 32 bits. A0 and A-1 is
used for matching when the x16 bit data bus is se-
42
Am29BDD160G
June 7, 2006
SPANSION [ SPANSION ]
