M29W640FB STMICROELECTRONICS [STMicroelectronics], M29W640FB Datasheet - Page 65

• Manufacturer Part Number: M29W640FB
• Description: 64 Mbit (8Mb x8 or 4Mb x16, Page, Boot Block) 3V Supply Flash Memory
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M29W640FT, M29W640FB
Appendix D Block Protection
D.1
D.2
Note:
and
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
Programmer technique, the In-System technique and Temporary Unprotection. Temporary
Unprotection is controlled by the Reset/Block Temporary Unprotection pin, RP; this is described
Programmer Technique
In-System Technique
RP can be either at V
Block protection can be used to prevent any operation from modifying the data stored in the
memory. The blocks are protected in groups, refer to
in the Signal Descriptions section.
The Programmer technique uses high (V
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
Protect
then all groups can be unprotected at the same time. To unprotect the chip follow
Programmer Equipment Chip Unprotect
Operations, BYTE = VIH or
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 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.
The In-System technique requires a high voltage level on the Reset/Blocks Temporary
Unprotect pin, RP
components on the microprocessor bus, therefore this technique is suitable for use after the
memory has been fitted to the system.
To protect a group of blocks follow the flowchart in
Protect
then all the groups can be unprotected at the same time. To unprotect the chip follow
In-System 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 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.
Block.
Table 21
Flowchart. To unprotect the whole chip it is necessary to protect all of the groups first,
Flowchart. To unprotect the whole chip it is necessary to protect all of the groups first,
for details of the Protection Groups. Once protected, Program and Erase
(1)
. This can be achieved without violating the maximum ratings of the
IH
or at V
VIL, gives a summary of each operation.
ID
when using the In-System Technique to protect the Extended
Flowchart.
Flowchart.
ID
) voltage levels on some of the bus pins. These
Figure 16: Programmer Equipment Group
Figure 18: In-System Equipment Group
Table 29: Programmer Technique Bus
Appendix A: Block
addresses,
9 Part Numbering
Figure 17:
Table 20
Figure 19:
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