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CHAPTER 22 DUAL OPERATION FLASH MEMORY
22.3 Registers of Flash Memory
22.3.2
Flash Memory Write Control Register (FWR0/FWR1)
The flash memory write control register (FWR0/FWR1) is a register in the flash memory
interface, used to set the accidental write preventive function for the flash memory.
■ Flash Memory Write Control Register (FWR0/FWR1)
The flash memory write control register (FWR0/FWR1) contains the write-enable/protect bits for
individual sectors (SA0 to SA9). The initial value of the bits is "0" to disable writing to the sectors. Writing
"1" to one of the bits enabled to write the corresponding sector. Writing "0" to it prevents an accidental
write from being executed to the sector. Once you have written "0" to the bit, therefore, you cannot write to
the sector even though you write "1" to the bit. When you write to the sector again, you have to reset the
bit.
Figure 22.3-3 Flash Memory Write Control Register (FWR0/FWR1)
R/W : Read/write enabled
0
: Write protected [Initial value]
484
bit 7
FWR0
00790C
SA7E SA6E SA5E SA4E SA3E SA2E SA1E SA0E
H
(
0
)
R/W
bit 15
FWR1
-
00790D
H
(
0
)
R/W
FUJITSU MICROELECTRONICS LIMITED
6
5
4
3
(
0
)
(
0
)
(
0
)
(
0
R/W
R/W
R/W
R/W
14
13
12
11
-
-
-
-
(
0
)
(
0
)
(
0
)
(
0
R/W
R/W
R/W
R/W
MB90335 Series
2
1
0
)
(
0
)
(
0
)
(
0
)
R/W
R/W
R/W
10
9
8
-
SA9E SA8E
)
(
0
)
(
0
)
(
0
)
R/W
R/W
R/W
CM44-10137-6E
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