25lc256 Microchip Technology Inc., 25lc256 Datasheet - Page 10

• Manufacturer Part Number: 25lc256
• Description: 256k Spi Bus Serial Eeprom
• Manufacturer: Microchip Technology Inc.

25AA256/25LC256
2.5
The Read Status Register instruction (RDSR) provides
access to the STATUS register. The STATUS register
may be read at any time, even during a write cycle. The
STATUS register is formatted as follows:
TABLE 2-2:
The Write-In-Process (WIP) bit indicates whether the
25XX256 is busy with a write operation. When set to a
‘
in progress. This bit is read-only.
FIGURE 2-6:
DS21822F-page 10
1
W/R = writable/readable. R = read-only.
WPEN
SCK
’, a write is in progress, when set to a ‘
W/R
CS
SO
7
SI
Read Status Register Instruction
(RDSR)
6
x
-
0
x
5
-
0
READ STATUS REGISTER TIMING SEQUENCE (RDSR)
STATUS REGISTER
4
x
-
0
1
W/R
High-Impedance
BP1
3
0
Instruction
2
W/R
BP0
0
2
3
0
WEL
0
4
R
1
’, no write is
1
5
WIP
R
0
0
6
1
7
The Write Enable Latch (WEL) bit indicates the status
of the write enable latch and is read-only. When set to
a ‘
‘
this bit can always be updated via the WREN or WRDI
commands, regardless of the state of write protection
on the STATUS register. These commands are shown
in Figure 2-4 and Figure 2-5.
The Block Protection (BP0 and BP1) bits indicate
which blocks are currently write-protected. These bits
are set by the user issuing the WRSR instruction. These
bits are nonvolatile, and are shown in Table 2-3.
See Figure 2-6 for the RDSR timing sequence.
7
0
8
’, the latch prohibits writes to the array. The state of
1
’, the latch allows writes to the array, when set to a
6
9
Data from STATUS Register
10
5
11
4
© 2007 Microchip Technology Inc.
12
3
13
2
14
1
15
0