M50FW002 データシートの表示（PDF） - STMicroelectronics
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M50FW002 Datasheet PDF : 39 Pages
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M50FW002
FIRMWARE HUB (FWH) INTERFACE CONFIGURATION REGISTERS
When the Firmware Hub Interface is selected sev-
eral additional registers can be accessed. These
registers control the protection status of the
Blocks, read the General Purpose Input pins and
identify the memory using the Electronic Signature
codes. See Table 11 for the memory map of the
Configuration Registers.
Lock Registers
The Lock Registers control the protection status of
the Blocks. Each Block has its own 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 12 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 Erase Command). When
the Write Lock Bit is set, ‘1’, the block is write pro-
tected; 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 re-
set, ‘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 6) is write
protected and cannot be modified. Similarly, if
Write Protect, WP, is Low, VIL, then the blocks 0 to
5 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.
Firmware Hub (FWH) General Purpose Input
Register
The Firmware Hub (FWH) General Purpose Input
Register holds the state of the Firmware Hub Inter-
face General Purpose Input pins, FGPI0-FGPI4.
When this register is read, the state of these pins
is returned. This register is read-only and writing to
it has no effect.
The signals on the Firmware Hub Interface Gener-
al Purpose Input pins should remain constant
throughout the whole Bus Read cycle in order to
guarantee that the correct data is read.
Manufacturer Code Register
Reading the Manufacturer Code Register returns
the manufacturer code for the memory. The man-
ufacturer code for STMicroelectronics is 20h. This
register is read-only and writing to it has no effect.
Device Code Register
Reading the Device Code Register returns the de-
vice code for the memory (29h). This register is
read-only and writing to it has no effect.
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