參數(shù)資料
型號: 25LC256-EPG
廠商: Microchip Technology Inc.
元件分類: EEPROM
英文描述: 256K SPI Bus Serial EEPROM
中文描述: 256K SPI總線串行EEPROM
文件頁數(shù): 11/26頁
文件大?。?/td> 367K
代理商: 25LC256-EPG
2003 Microchip Technology Inc.
Preliminary
DS21822C-page 11
25AA256/25LC256
2.6
Write Status Register Instruction
(
WRSR
)
The Write Status Register instruction (
WRSR
) allows the
user to write to the nonvolatile bits in the Status register
as shown in Table 2-2. The user is able to select one of
four levels of protection for the array by writing to the
appropriate bits in the Status register. The array is
divided up into four segments. The user has the ability
to write-protect none, one, two, or all four of the
segments of the array. The partitioning is controlled as
shown in Table 2-3.
The Write-Protect Enable (WPEN) bit is a nonvolatile
bit that is available as an enable bit for the WP pin. The
Write-Protect (WP) pin and the Write-Protect Enable
(WPEN) bit in the Status register control the
programmable hardware write-protect feature. Hard-
ware write protection is enabled when WP pin is low
and the WPEN bit is high. Hardware write protection is
disabled when either the WP pin is high or the WPEN
bit is low. When the chip is hardware write-protected,
only writes to nonvolatile bits in the Status register are
disabled. See Table 2-4 for a matrix of functionality on
the WPEN bit.
See Figure 2-7 for the
WRSR
timing sequence.
TABLE 2-3:
ARRAY PROTECTION
FIGURE 2-7:
WRITE STATUS REGISTER TIMING SEQUENCE (
WRSR
)
BP1
BP0
Array Addresses
Write-Protected
0
0
0
1
none
upper 1/4
(6000h - 7FFFh)
upper 1/2
(4000h - 7FFFh)
all
(0000h - 7FFFh)
1
0
1
1
SO
SI
CS
9
10
11
12
13
14
15
0
1
0
0
0
0
0
0
7
6
5
4
2
1
0
instruction
data to Status register
high-impedance
SCK
0
2
3
4
5
6
7
1
8
3
Note:
An internal write cycle (T
WC
) is initiated on the rising edge of CS after a valid write Status Register sequence.
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