at25dq321a ATMEL Corporation, at25dq321a Datasheet - Page 28

• Manufacturer Part Number: at25dq321a
• Description: 32-megabit 2.7-volt Minimum Spi Serial Flash Memory With Dual-i/o And Quad-i/o Support
• Manufacturer: ATMEL Corporation

28
Table 9-2.
Essentially, if the SPRL bit of the Status Register is in the logical “0” state (Sector Protection Registers are not
locked), then writing a 00h to the first byte of the Status Register will perform a Global Unprotect without changing
the state of the SPRL bit. Similarly, writing a 7Fh to the first byte of the Status Register will perform a Global Protect
and keep the SPRL bit in the logical “0” state. The SPRL bit can, of course, be changed to a logical “1” by writing an
FFh if software-locking or hardware-locking is desired along with the Global Protect.
If the desire is to only change the SPRL bit without performing a Global Protect or Global Unprotect, then the
system can simply write a 0Fh to the first byte of the Status Register to change the SPRL bit from a logical “1” to a
logical “0” provided the WP pin is deasserted. Likewise, the system can write an F0h to change the SPRL bit from
AT25DQ321A [Preliminary]
State
WP
0
0
1
1
Current
SPRL
Value
0
1
0
1
Valid SPRL and Global Protect/Unprotect Conditions
New Write Status
Register Byte 1
7 6 5 4 3 2 1 0
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
0 x 0 0 0 0 x x
0 x 0 0 0 1 x x
0 x 1 1 1 0 x x
0 x 1 1 1 1 x x
1 x 0 0 0 0 x x
1 x 0 0 0 1 x x
1 x 1 1 1 0 x x
1 x 1 1 1 1 x x
x x x x x x x x
Data
Bit
Protection Operation
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
No change to the current protection level. All sectors currently protected will remain protected
and all sectors currently unprotected will remain unprotected.
The Sector Protection Registers are hard-locked and cannot be changed when the WP pin is
LOW and the current state of SPRL is 1. Therefore, a Global Protect/Unprotect will not occur.
In addition, the SPRL bit cannot be changed (the WP pin must be HIGH in order to change
SPRL back to a 0).
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
Global Unprotect – all Sector Protection Registers reset to 0
No change to current protection.
No change to current protection.
No change to current protection.
Global Protect – all Sector Protection Registers set to 1
No change to the current protection level. All sectors currently protected will remain
protected, and all sectors currently unprotected will remain unprotected.
The Sector Protection Registers are soft-locked and cannot be changed when the
current state of SPRL is 1. Therefore, a Global Protect/Unprotect will not occur.
However, the SPRL bit can be changed back to a 0 from a 1 since the WP pin is
HIGH. To perform a Global Protect/Unprotect, the Write Status Register command
must be issued again after the SPRL bit has been changed from a 1 to a 0.
8718A–DFLASH–04/10
SPRL
Value
New
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1