MBM29QM12DH Fujitsu Microelectronics, Inc., MBM29QM12DH Datasheet - Page 39

• Manufacturer Part Number: MBM29QM12DH
• Description: Page Mode Flash Memory 128m 8m X 16 Bit
• Manufacturer: Fujitsu Microelectronics, Inc.

38
MBM29QM12DH
DPB Write(Erase) Command
DPB verify command
PPB Lock Bit verify command
Password Unlock Command
PPB Program Command
The DPB Write command is used to set or clear a DPB for a given sector. The high order address bits (A
A
during the data write cycle. The DPBs are modifiable at any time, regardless of the state of the PPB or PPB
Lock Bit. The DPBs are cleared at power-up or hardware reset.Exiting the DPB Write command is accomplished
by writing the HiddenROM Exit command.
DPB verify command is uesed to verify the status of a DPB for given sector.Scanning the sector addresses (SA)
will produce a logical "1" at the device output DQ
at DQ
normal operation.
PPB Lock Bit verify command is used to verify the status of a PPB Lock Bit. A logical "1" at the device output
DQ
Exit Command returns the device back to normal operation.
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 accessible 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 s 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 s execution window for each portion of the unlock, the command
will be ignored.
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. A
match separated 16 bits. Writing the Password Unlock command is address order specific. In other words, the
lowers address A
Writing out of sequence results in the Password Unlock not returning a match with the password and the PPB
Lock Bit remains set.
Once the Password Unlock command is entered, the RY/BY pin goes LOW indicating that the device is busy.
Also, reading the Bank A results in the DQ
progress. Reading the other bank returns actual array data. Approximately 2 µs is required for each portion of
the unlock. Once the first portion of the password unlock completes (RY/BY is not driven and DQ
toggle when read), the next cycle is issued, only this time with the next part of the password. Seven cycles
Password Unlock commands are required to successfully clear the PPB Lock Bit. As with the first Password
Unlock command, the RY/BY signal goes LOW and reading the device results in the DQ
successive read operations until complete. It is the responsibility of the microprocessor to keep track of the
number of Password Unlock cycles, the order, and when to read the PPB Lock bit to confirm successful password
unlock. Writing the HiddenROM Exit Command returns the device back to normal operation.
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 specific sector address (A
as the program command 60h. 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
issuing "SGA WP/68h" at 4th bus cycle, the device requires approximately 150 µs time out period for program-
ming the PPB. Then by writing "SGA
DQ
cycle of "SGA
The PPB Program command does not follow the Embedded Program algorithm. Writing the HiddenROM Exit
Command returns the device back to normal operation.
12
) are issued at the same time as the code 01h or 00h on DQ
1
0
indicates that the PPB Lock Bit is set. If PPB Lock Bit is not set, DQ
0
1 then PPB is programmed. If not, then the user needs to repeat this program sequence from the 4th
for the sector which is not protected. Writing the HiddenROM Exit Command returns the device back to
WP/68h".
1
:A
0
00, the next cycle command is to A
-60
WP/48h" at 5th bus cycle, the device outputs verify data at DQ
0
6
and A
pin toggling, indicating that the Password Unlock function is in
0
for a protected sector. Otherwise the device will produce "0"
1
are used to determine the 16 bit data quantity is used to
1
:A
0
7
01, then to A
to DQ
0
. All other DQ data bus pins are ignored
1
will output "0". Writing the HiddenROM
22
to A
1
:A
12
0
) are written at the same time
10, and finally to A
6
pin toggling on
6
1
does not
:A
0
. If
0
22
11.
to