AT45DB321C-RI ATMEL [ATMEL Corporation], AT45DB321C-RI Datasheet - Page 8

• Manufacturer Part Number: AT45DB321C-RI
• Description: 32 MEGABIT 2.7 VOLT DATAFLASH
• Manufacturer: ATMEL [ATMEL Corporation]

Sector Protection
8
AT45DB321C [Preliminary]
Two protection methods, hardware and software controlled, are provided. The selection
of which sectors to be protected/unprotected from program and erase operations is
defined in the Sector Protection Register.
SOFTWARE SECTOR PROTECTION: 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 com-
mand. 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.
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 Disable Sector Protection command is ignored while the WP pin is
asserted.
Software Sector 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 pulled high internally) and sector protection can be controlled using the soft-
ware commands.
If the device is power cycled, then the Software Sector Protection will be disabled. Once
the device is powered up, the Enable Sector Protection command should be reissued if
sector protection is desired and if the WP pin is not used. The RESET pin has no effect
on the Software Sector Protection.
HARDWARE SECTOR PROTECTION: Sectors specified for protection in Sector Pro-
tection Register can be protected from program and erase operations by utilizing the
Write Protection (WP) pin. The protection can be enabled by asserting the WP pin and
keeping the pin in its asserted state. Any sector specified for protection cannot be
erased or reprogrammed as long as the WP pin is asserted. The protection can be dis-
abled by deasserting the WP pin high. A filter is provided on the WP pin to help protect
against spurious noise on the WP pin. Hardware Sector Protection will provide continu-
ous protection, based on the contents of the Sector Protection Register, in an
application where WP is always driven low. Please read the description of the WP pin on
page 13 for more information.
SECTOR PROTECTION REGISTER: Sector Protection Register is a nonvolatile regis-
ter that contains 16 bytes of data, as shown below:
Command
Enable Sector Protection
Disable Sector Protection
Read Sector Protection Register
Sector Number
Protected
Unprotected
Byte 1
3DH
3DH
32H
See Below
0 (0a, 0b)
Byte 2
2AH
2AH
00H
Byte 3
7FH
7FH
00H
1 to 15
FFH
00H
3387B–DFLSH–9/04
Byte 4
A9H
9AH
00H