M50LPW116 데이터 시트보기 (PDF) - STMicroelectronics
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M50LPW116 Datasheet PDF : 36 Pages
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M50LPW116
Lock Registers
The Lock Registers control the protection status of
the Blocks. Each Block has its own Lock Register.
Blocks 0 to 15 have the same Lock Register.
Three bits within each Lock Register control the
protection of each block, the Write Lock Bit, the
Read Lock Bit and the Lock Down Bit.
The Lock Registers can be read and written,
though care should be taken when writing as, once
the Lock Down Bit is set, ‘1’, further modifications
to the Lock Register cannot be made until cleared,
to ‘0’, by a reset or power-up.
See Table 15 for details on the bit definitions of the
Lock Registers.
Write Lock. The Write Lock Bit determines
whether the contents of the Block can be modified
(using the Program or Block Erase Command).
When the Write Lock Bit is set, ‘1’, the block is
write protected; any operations that attempt to
change the data in the block will fail and the Status
Register will report the error. When the Write Lock
Bit is reset, ‘0’, the block is not write protected
through the Lock Register and may be modified
unless write protected through some other means.
When VPP is less than VPPLK all blocks are pro-
tected and cannot be modified, regardless of the
state of the Write Lock Bit. If Top Block Lock, TBL,
is Low, VIL, then the Top Block (Block 49) is write
protected and cannot be modified. Similarly, if
Write Protect, WP, is Low, VIL, then the Blocks 0
to 48 are write protected and cannot be modified.
After power-up or reset the Write Lock Bit is al-
ways set to ‘1’ (write protected).
Read Lock. The Read Lock bit determines
whether the contents of the Block can be read
(from Read mode). When the Read Lock Bit is set,
‘1’, the block is read protected; any operation that
attempts to read the contents of the block will read
00h instead. When the Read Lock Bit is reset, ‘0’,
read operations in the Block return the data pro-
grammed into the block as expected.
After power-up or reset the Read Lock Bit is al-
ways reset to ‘0’ (not read protected).
Lock Down. The Lock Down Bit provides a
mechanism for protecting software data from sim-
ple hacking and malicious attack. When the Lock
Down Bit is set, ‘1’, further modification to the
Write Lock, Read Lock and Lock Down Bits cannot
be performed. A reset or power-up is required be-
fore changes to these bits can be made. When the
Lock Down Bit is reset, ‘0’, the Write Lock, Read
Lock and Lock Down Bits can be changed.
General Purpose Input Register
The General Purpose Input Register holds the
state of the General Purpose Input pins, GPI0-
GPI4. When this register is read, the state of these
pins is returned. This register is read-only and writ-
ing to it has no effect.
The signals on the General Purpose Input pins
should remain constant throughout the whole Bus
Read cycle in order to guarantee that the correct
data is read.
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