12

AT45DB321D [DATASHEET]

3597R–DFLASH–11/2012

Table 7-1.

WP Pin and Protection Status

7.1

Sector Protection Register

The nonvolatile sector protection register specifies which sectors are to be protected or unprotected with either the software or

hardware controlled protection method. The sector protection register contains 64 bytes of data, in which byte locations 0

through 63 contain values that specify whether sectors 0 through 63 will be protected or unprotected. The sector protection

register is user modifiable, and must first be erased before it can be reprogrammed. Table 7-3 illustrates the format of the sector

protection register.

Table 7-2.

Sector Protection Register

Note:

1.

x = don’t care.

7.1.1

Erase Sector Protection Register Command

In order to modify and change the value of the sector protection register, it must first be erased using the erase sector protection

register command.

To erase the sector protection register, the CS pin must first be asserted, as it would be with any other command. Once the CS

pin has been asserted, the appropriate four-byte opcode sequence must be clocked into the device via the SI pin. The four-byte

opcode sequence must start with 3DH, and be followed by 2AH, 7FH, and CFH. After the last bit of the opcode sequence has

been clocked in, the CS pin must be deasserted to initiate the internally self-timed erase cycle. The erasing of the sector

is busy. If the device is powered down before the completion of the erase cycle, then the contents of the sector protection

register cannot be guaranteed.

Time

Period

WP Pin

Enable Sector Protection

Command

Disable Sector

Protection Command

Sector

Protection

Status

Sector

Protection

Register

1

High

Command not issued previously

–

Issue command

X

Issue command

–

Disabled

Disabled

Enabled

Read/write

Read/write

Read/write

2

Low

X

X

Enabled

Read only

3

High

Command issued during period 1 or 2

–

Issue command

Not issued yet

issue command

–

Enabled

Disabled

Enabled

Read/write

Read/write

Read/write

Sector Number

0 (0a, 0b)

1 to 63

Protected

See Table 7-3

FFH

Unprotected

00H

Table 7-3.

Sector 0 (0a, 0b)

0a

0b

Bit 3, 2

Data

Value

(Pages 0-7)

(Pages 8-127)

Bit 7, 6

Bit 5, 4

Bit 1, 0

Sectors 0a, 0b unprotected

00

00

xx

xx

0xH

Protect sector 0a (pages 0-7)

11

00

xx

xx

CxH

Protect sector 0b (pages 8-127)

00

11

xx

xx

3xH

Protect sectors 0a (pages 0-7), 0b (pages 8-127)(1)

11

11

xx

xx

FxH