MBM29QM12DH Fujitsu Microelectronics, Inc., MBM29QM12DH Datasheet - Page 33

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

32
MBM29QM12DH
Read/Reset Command
Autoselect Command
COMMAND DEFINITION
Device operations are selected by writing specific address and data sequences into the command register. Some
commands require Bank Address (BA) input. When command sequences are input into a bank reading, the
commands have priority over the reading. “MBM29QM12DH Command Definitions Table” in “
OPERATION” shows the valid register command sequences. Note that the Erase Suspend (B0h) and Erase
Resume (30h) commands are valid only while the Sector Erase operation is in progress. Also the Program
Suspend (B0h) and Program Resume (30h) commands are valid only while the Program operation is in progress.
Moreover, Read/Reset commands are functionally equivalent, resetting the device to the read mode. Please
note that commands are always written at DQ
and data values or writing them in the improper sequence will take the device into unknow state.
In order to return from Autoselect mode or Exceeded Timing Limits (DQ
Reset operation is initiated by writing the Read/Reset command sequence into the command register. Micro-
processor read cycles retrieve array data from the memory. The device remains enabled for reads until the
command register contents are altered.
The device will automatically power-up in the Read/Reset state. In this case a command sequence is not required
in order to read data. Standard microprocessor read cycles will retrieve array data. This default value ensures
that no spurious alteration of the memory content occurs during the power transition. Refer to AC Read Char-
acteristics and Timing Diagram for the specific timing parameters.
Flash memories are intended for use in applications where the local CPU alters memory contents. Therefore,
manufacture and device codes must be accessible while the device resides in the target system. PROM pro-
grammers typically access the signature codes by raising A
voltage onto the address lines is not generally desired system design practice.
The device contains an Autoselect command operation to supplement traditional PROM programming method-
ology. The operation is initiated by writing the Autoselect command sequence into the command register.
The Autoselect command sequence is initiated first by writing two unlock cycles. This is followed by a third write
cycle that contains the bank address (BA) and the Autoselect command. Then the manufacture and device
codes can be read from the bank, and actual data from the memory cell can be read from another bank. The
higher order address (A
bank address (BA) set at the third write cycle.
Following the command write, in WORD mode, a read cycle from address (BA) 00h returns the manufacturer’s
code (Fujitsu
indicates that two additional codes, called Extended Device Codes will be required. Therefore the system may
continue reading out these Extended Device Codes at the address of (BA) 0Eh, as well as at (BA) 0Fh. Notice
that the above applies to WORD mode. (Refer to “MBM29QM12DH Sector Group Protection Verify Autoselect
Codes Table” and “Extended Autoselect Code Table” in “ DEVICE BUS OPERATION” )
The sector state (PPB protection or PPB unprotection) will be informed by address (BA) XX02h for
the sector group addresses (A
A
programming verification should be performed by verifying sector group protection on the protected sector. (See
“MBM29QM12DH User Bus Operations Table” and “MBM29QM12DH Command Definitions Table” in “ DEVICE
BUS OPERATION”.)
The manufacture and device codes can be read from the selected bank. To read the manufacture and device
codes and sector protection status from a non-selected bank, it is necessary to write the Read/Reset command
sequence into the register. Autoselect command should then be written into the bank to be read.
If the software (program code) for Autoselect command is stored in the Flash memory, the device and manu-
facture codes should be read from the other bank, which does not contain the software.
1
,A
0
)
(0, 0, 0, 0, 0, 0, 1, 0) will produce a logical “1” at device output DQ
04h) . And a read cycle at address (BA) 01h outputs device code. When 227Eh was output, this
22
, A
21
, A
22
, A
-60
20
) required for reading out the manufacture and device codes demands the
21
, A
20
, A
19
7
to DQ
, A
18
, A
0
and DQ
17
, A
16
, A
15
9
15
to DQ
to a higher voltage. However, multiplexing high
, A
14
8
, A
bits are ignored. Writing incorrect address
13
5
, and A
1) to Read/Reset mode, the Read/
0
for a protected sector group. The
12
) while(A
7
, A
6
, A
DEVICE BUS
5
, A
. Scanning
4
, A
3
, A
2
,