MBM29PDS322TE Fujitsu Microelectronics, Inc., MBM29PDS322TE Datasheet - Page 27

• Manufacturer Part Number: MBM29PDS322TE
• Description: Flash Memory 32m 2m X 16 Bit Page Dual Operation
• Manufacturer: Fujitsu Microelectronics, Inc.

Hidden ROM (Hi-ROM) Region
Hidden ROM (Hi-ROM) Entry Command
Hidden ROM (Hi-ROM) Program Command
Hidden ROM (Hi-ROM) Erase Command
The Hi-ROM feature provides a Flash memory region that the system may access through a new command
sequence. This is primarily intended for customers who wish to use an Electronic Serial Number (ESN) in the
device with the ESN protected against modification. Once the Hi-ROM region is protected, any further modifi-
cation of that region is impossible. This ensures the security of the ESN once the product is shipped to the field.
The Hi-ROM region is 32 Kwords in length and is stored at the same address as the 4 KW 8 sectors. The
MBM29PDS322TE occupies the address of the word mode 1F8000h to 1FFFFFh and the MBM29PDS322BE
type occupies the address of the word mode 000000h to 007FFFh. After the system has written the Enter Hi-
ROM command sequence, the system may read the Hi-ROM region by using the addresses normally occupied
by the boot sectors. That is, the device sends all commands that would normally be sent to the boot sectors to
the Hi-ROM region. This mode of operation continues until the system issues the Exit Hi-ROM command se-
quence, or until power is removed from the device. On power-up, or following a hardware reset, the device reverts
to sending commands to the boot sectors.
When reading the Hi-ROM region, either change addresses or change CE pin from “H” to “L”. The same procedure
should be taken (changing addresses or CE pin from “H” to “L”) after the system issues the Exit Hi-ROM command
sequence to read actual data of memory cell.
The device has a Hidden ROM area with One Time Protect function. This area is to enter the security code and
to unable the change of the code once set. Program/erase is possible in this area until it is protected. However,
once it is protected, it is impossible to unprotect, so please use this with caution.
Hidden ROM area is 32 K words and in the same address area as 4 KW sector. The address of top boot is
1F8000h to 1FFFFFh at word mode and the bottom boot is 000000h to 007FFFh at word mode. These areas
are normally the boot block area (4 KW 8 sector). Therefore, write the Hidden ROM entry command sequence
to enter the Hidden ROM area. It is called Hidden ROM mode when the Hidden ROM area appears.
Sector other than the boot block area could be read during Hidden ROM mode. Read/program/erase of the
Hidden ROM area is possible during Hidden ROM mode. Write the Hidden ROM reset command sequence to
exit the Hidden ROM mode. The bank address of the Hidden ROM should be set on the third cycle of this reset
command sequence.
To program the data to the Hidden ROM area, write the Hidden ROM program command sequence during Hidden
ROM mode. This command is the same as the program command in usual except to write the command during
Hidden ROM mode. Therefore the detection of completion method is the same as in the past, using the DQ
data poling, DQ
the address other than the Hidden ROM area is selected to program, data of the address will be changed.
To erase the Hidden ROM area, write the Hidden ROM erase command sequence during Hidden ROM mode.
This command is same as the sector erase command in the past except to write the command during Hidden
ROM mode. Therefore the detection of completion method is the same as in the past, using the DQ
DQ
address other than the Hidden ROM area is selected, the data of the sector will be changed.
6
toggle bit and RY/BY pin. It is necessary to pay attention to the sector address to be erased. If the sector
6
toggle bit and RY/BY pin. It is necessary to pay attention to the address to be programmed. If
MBM29PDS322TE/BE
7
data poling,
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7
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