AT25DF321A_10 Datasheet, PDF (21/52 Pages) ATMEL Corporation – 32-Mbit 2.7V Minimum Serial Peripheral Interface Serial Flash Memory

Atmel AT25DF321A
9.5 Global Protect/Unprotect
The Global Protect and Global Unprotect features can work in conjunction with the Protect Sector and Unprotect Sector
functions. For example, a system can globally protect the entire memory array and then use the Unprotect Sector
command to individually unprotect certain sectors and individually reprotect them later by using the Protect Sector
command. Likewise, a system can globally unprotect the entire memory array and then individually protect certain sectors
as needed.
Performing a Global Protect or Global Unprotect is accomplished by writing a certain combination of data to the Status
Register using the Write Status Register Byte 1 command (see “Write Status Register Byte 1” on page 34 for command
execution details). The Write Status Register command is also used to modify the SPRL (Sector Protection Registers
Locked) bit to control hardware and software locking.
To perform a Global Protect, the appropriate WP pin and SPRL conditions must be met, and the system must write a logical
“1” to bits five, four, three and two of the first byte of the Status Register. Conversely, to perform a Global Unprotect, the
same WP and SPRL conditions must be met but the system must write a logical “0” to bits five, four, three and two of the
first byte of the Status Register. Table 9-2 details the conditions necessary for a Global Protect or Global Unprotect to be
performed.
Sectors that have been erase or program suspended must remain in the unprotected state. If a Global Protect operation is
attempted while a sector is erase or program suspended, the protection operation will abort, the protection states of all
sectors in the Flash memory array will not change, and WEL bit in the Status Register will be reset back to a logical “0”.
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