AT45DB321D datasheet(13/57 Pages) ATMEL

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3597N–DFLASH–04/09

AT45DB321D

9. Hardware Controlled Protection

Sectors specified for protection in the Sector Protection Register and the Sector Protection Reg-

ister itself can be protected from program and erase operations by asserting the WP pin and

keeping the pin in its asserted state. The Sector Protection Register and any sector specified for

protection cannot be erased or reprogrammed as long as the WP pin is asserted. In order to

modify the Sector Protection Register, the WP pin must be deasserted. If the WP pin is perma-

nently connected to GND, then the content of the Sector Protection Register cannot be changed.

If the WP pin is deasserted, or permanently connected to VCC, then the content of the Sector

Protection Register can be modified.

The WP pin will override the software controlled protection method but only for protecting the

sectors. For example, if the sectors were not previously protected by the Enable Sector Protec-

tion command, then simply asserting the WP pin would enable the sector protection within the

maximum specified tWPE time. When the WP pin is deasserted; however, the sector protection

would no longer be enabled (after the maximum specified tWPD time) as long as the Enable Sec-

tor Protection command was not issued while the WP pin was asserted. If the Enable Sector

Protection command was issued before or while the WP pin was asserted, then simply deassert-

ing the WP pin would not disable the sector protection. In this case, the Disable Sector

Protection command would need to be issued while the WP pin is deasserted to disable the sec-

tor protection. The Disable Sector Protection command is also ignored whenever the WP pin is

asserted.

A noise filter is incorporated to help protect against spurious noise that may inadvertently assert

or deassert the WP pin.

The table below details the sector protection status for various scenarios of the WP pin, the

Enable Sector Protection command, and the Disable Sector Protection command.

Figure 9-1.

WP Pin and Protection Status

Table 9-1.

WP Pin and Protection Status

Time

Period

WP Pin

Enable Sector Protection

Command

Disable Sector

Protection Command

Sector Protection

Status

Sector

Protection

1High

Command Not Issued Previously

–

Issue Command

–

Disabled

Enabled

Read/Write

Low

Enabled

Read Only

3High

Command Issued During Period 1

or 2

–

Issue Command

Not Issued Yet

Issue Command

–

Enabled

Disabled

Enabled

Read/Write

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