8.1
8.1.1
Software Sector Protection
Enable Sector Protection Command
Sectors specified for protection in the Sector Protection Register can be protected from program
and erase operations by issuing the Enable Sector Protection command. To enable the sector
protection using the software controlled method, the CS pin must first be asserted as it would be
with any other command. Once the CS pin has been asserted, the appropriate 4-byte command
sequence must be clocked in via the input pin (SI). After the last bit of the command sequence
has been clocked in, the CS pin must be deasserted after which the sector protection will be
enabled.
Command
Enable Sector Protection
Byte 1
3DH
Byte 2
2AH
Byte 3
7FH
Byte 4
A9H
Figure 8-1.
Enable Sector Protection
CS
SI
Opcode
Byte 1
Each transition
represents 8 bits
Opcode
Byte 2
Opcode
Byte 3
Opcode
Byte 4
8.1.2
Disable Sector Protection Command
To disable the sector protection using the software controlled method, the CS pin must first be
asserted as it would be with any other command. Once the CS pin has been asserted, the
appropriate 4-byte sequence for the Disable Sector Protection command must be clocked in via
the input pin (SI). After the last bit of the command sequence has been clocked in, the CS pin
must be deasserted after which the sector protection will be disabled. The WP pin must be in the
deasserted state; otherwise, the Disable Sector Protection command will be ignored.
Command
Disable Sector Protection
Byte 1
3DH
Byte 2
2AH
Byte 3
7FH
Byte 4
9AH
Figure 8-2.
Disable Sector Protection
CS
SI
Opcode
Byte 1
Each transition
represents 8 bits
Opcode
Byte 2
Opcode
Byte 3
Opcode
Byte 4
8.1.3
Various Aspects About Software Controlled Protection
Software controlled protection is useful in applications in which the WP pin is not or cannot be
controlled by a host processor. In such instances, the WP pin may be left floating (the WP pin is
internally pulled high) and sector protection can be controlled using the Enable Sector Protection
and Disable Sector Protection commands.
If the device is power cycled, then the software controlled protection will be disabled. Once the
device is powered up, the Enable Sector Protection command should be reissued if sector pro-
tection is desired and if the WP pin is not used.
12
AT45DB041D
3595L–DFLASH–4/08
ATMEL [ ATMEL CORPORATION ]
