MX25L12835F
Software Protected Mode (SPM):
-
When SRWD bit=0, no matter WP#/SIO2 is low or high, the WREN instruction may set the WEL bit and can
change the values of SRWD, BP3, BP2, BP1, BP0. The protected area, which is defined by BP3, BP2, BP1,
BP0 and T/B bit, is at software protected mode (SPM).
-
When SRWD bit=1 and WP#/SIO2 is high, the WREN instruction may set the WEL bit can change the values
of SRWD, BP3, BP2, BP1, BP0. The protected area, which is defined by BP3, BP2, BP1, BP0 and T/B bit, is at
software protected mode (SPM)
Note:
If SRWD bit=1 but WP#/SIO2 is low, it is impossible to write the Status Register even if the WEL bit has previously
been set. It is rejected to write the Status Register and not be executed.
Hardware Protected Mode (HPM):
-
When SRWD bit=1, and then WP#/SIO2 is low (or WP#/SIO2 is low before SRWD bit=1), it enters the hardware
protected mode (HPM). The data of the protected area is protected by software protected mode by BP3, BP2,
BP1, BP0 and T/B bit and hardware protected mode by the WP#/SIO2 to against data modification.
Note:
To exit the hardware protected mode requires WP#/SIO2 driving high once the hardware protected mode is entered.
If the WP#/SIO2 pin is permanently connected to high, the hardware protected mode can never be entered; only
can use software protected mode via BP3, BP2, BP1, BP0 and T/B bit.
If the system enter QPI or set QE=1, the feature of HPM will be disabled.
Table 8. Protection Modes
Mode
Status register condition
WP# and SRWD bit status
Memory
Status register can be written
in (WEL bit is set to "1") and
the SRWD, BP0-BP3
Software protection
mode (SPM)
WP#=1 and SRWD bit=0, or
WP#=0 and SRWD bit=0, or
WP#=1 and SRWD=1
The protected area
cannot
be program or erase.
bits can be changed
The SRWD, BP0-BP3 of
status register bits cannot be
changed
The protected area
cannot
be program or erase.
Hardware protection
mode (HPM)
WP#=0, SRWD bit=1
Note:
1. As defined by the values in the Block Protect (BP3, BP2, BP1, BP0) bits of the Status Register, as shown in "Table 2.
Protected Area Sizes".
P/N: PM1795
REV. 1.0, OCT. 23, 2012
35
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