m29dw256g Numonyx, m29dw256g Datasheet - Page 23

• Manufacturer Part Number: m29dw256g
• Description: 256-mbit X16, Multiple Bank, Page, Dual Boot 3 V Supply Flash Memory
• Manufacturer: Numonyx

Figure 5.
1. NVPBs default to ‘1’ (block unprotected) after power-up and hardware reset. A block is protected or unprotected when its
2. VPB default status depends on ordering option. A block is protected or unprotected when its VPB is set to ‘0’ and ‘1’,
3. The NVPB lock bit is volatile and default to ‘1’ (NVPB bits unlocked) after power-up and hardware reset. NVPB bits are
5.4
5.4.1
NVPB is set to ‘0’ and ‘1’, respectively. NVPBs are programmed individually and cleared collectively.
respectively. VPBs are programmed and cleared individually. For the volatile protection to be effective, the NVPB lock bit
must be set to ‘0’ (NVPB bits unlocked) and the block NVPB must be set to ‘1’ (block unprotected).
locked by setting the NVPB lock bit to ‘0’. Once programmed to ‘0’, the NVPB lock bit can be reset to ‘1’ only be taking the
device through a power-up or hardware reset.
Parameter block or
main block
Software protection scheme
Lock register
The lock register is a 16-bit one-time programmable register. The bits in the lock register are
summarized in
The lock register allows configuration of memory blocks and extended memory block
protection (see
See
to read and program the lock register.
Extended block protection bit (DQ0)
If the device has not been shipped with the extended memory block factory locked, the
block can be protected by setting the extended memory block protection bit, DQ0, to ‘0’.
However, this bit is one-time programmable and once protected the extended memory block
cannot be unprotected.
The extended memory block protection status can be read in auto select mode either by
applying V
(see
Section 6.4.1: Lock Register Command Set
Table 10: Standard
ID
to A9 (see
Table 8: Lock register
Non-volatile protection
Table 9: Block protection
Volatile protection
Table 7: Block
commands).
VPB (2)
bits.
protection) or by issuing an Auto Select command
status).
NVPB (1)
for a description of the commands allowing
NVPB Lock bit (3)
Password protection
protection mode
Non-volatile
mode
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