AT25DF321 데이터 시트보기 (PDF) - Atmel Corporation

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AT25DF321

32-megabit 2.7-volt Minimum SPI Serial Flash Memory

Atmel Corporation 

issue the Unprotect Sector command will be ignored, and the device will reset the WEL bit in the

Status Register back to a logical “0” and return to the idle state once the CS pin has been

deasserted.

Figure 9-4. Unprotect Sector

CS

SCK

SI

SO

0 1 2 3 4 5 6 7 8 9 10 11 12

26 27 28 29 30 31

OPCODE

ADDRESS BITS A23-A0

0 0 1 1 1 0 0 1AAAAAA

MSB

MSB

AAAAAA

HIGH-IMPEDANCE

9.5 Global Protect/Unprotect

The Global Protect and Global Unprotect features can work in conjunction with the Protect Sec-

tor 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 sec-

tors 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 sec-

tors as needed.

Performing a Global Protect or Global Unprotect is accomplished by writing a certain combina-

tion of data to the Status Register using the Write Status Register command (see “Write Status

Register” section on page 21 for command execution details). The Write Status Register com-

mand 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 5, 4, 3, and 2 of the Status Register. Conversely, to per-

form a Global Unprotect, the same WP and SPRL conditions must be met but the system must

write a logical “0” to bits 5, 4, 3, and 2 of the Status Register. Table 9-2 details the conditions

necessary for a Global Protect or Global Unprotect to be performed.

14 AT26DF321

3633F–DFLASH–5/7/08

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