Rainbow Electronics AT45DB011D - Manual (Page 11)

11
3639J–DFLASH–11/2012
AT45DB011D
8. Sector Protection
Two protection methods, hardware and software controlled, are provided for protection against
inadvertent or erroneous program and erase cycles. The software controlled method relies on
the use of software commands to enable and disable sector protection while the hardware con-
trolled method employs the use of the Write Protect (WP) pin. The selection of which sectors
that are to be protected or unprotected against program and erase operations is specified in the
nonvolatile Sector Protection Register. The status of whether or not sector protection has been
enabled or disabled by either the software or the hardware controlled methods can be deter-
mined by checking the Status Register.
8.1 Software Sector Protection
8.1.1 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.
Table 8-1. Enable Sector Protection Command
Figure 8-1. Enable Sector Protection
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.
Table 8-2. Disenable Sector Protection Command
Command Byte 1 Byte 2 Byte 3 Byte 4
Enable Sector Protection 3DH 2AH 7FH A9H
Opcode
Byte 1
Opcode
Byte 2
Opcode
Byte 3
Opcode
Byte 4
CS
Each transition
represents 8 bits
SI
Command Byte 1 Byte 2 Byte 3 Byte 4
Disable Sector Protection 3DH 2AH 7FH 9AH