M29W320ET STMICROELECTRONICS [STMicroelectronics], M29W320ET Datasheet - Page 40

• Manufacturer Part Number: M29W320ET
• Description: 32 Mbit (4Mb x8 or 2Mb x16, Boot Block) 3V Supply Flash Memory
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M29W320ET, M29W320EB
APPENDIX D. BLOCK PROTECTION
Block protection can be used to prevent any oper-
ation from modifying the data stored in the memo-
ry. The blocks are protected in groups, refer to
APPENDIX
of the Protection Groups. Once protected, Pro-
gram and Erase operations within the protected
group fail to change the data.
There are three techniques that can be used to
control Block Protection, these are the Program-
mer technique, the In-System technique and Tem-
porary Unprotection. Temporary Unprotection is
controlled by the Reset/Block Temporary Unpro-
tection pin, RP; this is described in the Signal De-
scriptions section.
Programmer Technique
The Programmer technique uses high (V
age levels on some of the bus pins. These cannot
be achieved using a standard microprocessor bus,
therefore the technique is recommended only for
use in Programming Equipment.
To protect a group of blocks follow the flowchart in
Figure
Flowchart. To unprotect the whole chip it is neces-
sary to protect all of the groups first, then all
groups can be unprotected at the same time. To
unprotect the chip follow
Equipment Chip Unprotect
29., Programmer Technique Bus Operations,
BYTE = V
ation.
The timing on these flowcharts is critical. Care
should be taken to ensure that, where a pause is
Table 29. Programmer Technique Bus Operations, BYTE = V
Note: 1. Block Protection Groups are shown in
40/46
Block (Group)
Protect
Chip Unprotect
Block (Group)
Protection Verify
Block (Group)
Unprotection Verify
Operation
20., Programmer Equipment Block Protect
(1)
IH
A.,
or V
Table 20.
IL
, gives a summary of each oper-
V
V
V
V
E
ID
IL
IL
IL
and
Figure 21., Programmer
V
V
V
V
G
ID
ID
IL
IL
Table 21.
Flowchart.
V
V
IL
IL
V
V
W
APPENDIX
Pulse
Pulse
IH
IH
for details
ID
A0 = V
A0 = V
) volt-
Table
A9 = V
A.,
A9 = V
Table 20.
IL
IL
A12-A20 Block Address
A12-A20 Block Address
, A1 = V
, A1 = V
ID
ID
Address Inputs
, A12-A20 Block Address
, A12 = V
specified, it is followed as closely as possible. Do
not abort the procedure before reaching the end.
Chip Unprotect can take several seconds and a
user message should be provided to show that the
operation is progressing.
In-System Technique
The In-System technique requires a high voltage
level on the Reset/Blocks Temporary Unprotect
pin, RP
the maximum ratings of the components on the mi-
croprocessor bus, therefore this technique is suit-
able for use after the memory has been fitted to
the system.
To protect a group of blocks follow the flowchart in
Figure 22., In-System Equipment Group Protect
Flowchart. To unprotect the whole chip it is neces-
sary to protect all of the groups first, then all the
groups can be unprotected at the same time. To
unprotect the chip follow
Equipment Chip Unprotect
The timing on these flowcharts is critical. Care
should be taken to ensure that, where a pause is
specified, it is followed as closely as possible. Do
not allow the microprocessor to service interrupts
that will upset the timing and do not abort the pro-
cedure before reaching the end. Chip Unprotect
can take several seconds and a user message
should be provided to show that the operation is
progressing.
Note: 1. RP can be either at V
Others = X
Others = X
Others = X
Others = X
and
A0-A20
IH
IH
, A6 = V
Table 21.
, A6 = V
tem Technique to protect the Extended Block.
(1)
IH
, A15 = V
. This can be achieved without violating
IH
IH
IL
or V
, A9 = V
, A9 = V
IL
IH
ID
ID
,
,
IH
or at V
DQ15A–1, DQ14-DQ0
Data Inputs/Outputs
Flowchart.
Figure 23., In-System
Retry = XX00h
Retry = XX01h
Pass = XX01h
Pass = XX00h
ID
when using the In-Sys-
X
X