25AA512_10 Datasheet, PDF (12/36 Pages) Microchip Technology – 512 Kbit SPI Bus Serial EEPROM

25AA512
2.4 Read Status Register Instruction
(RDSR)
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: STATUS REGISTER
7
654 3
2
1
0
W/R – – – W/R W/R R
R
WPEN X X X BP1 BP0 WEL WIP
W/R = writable/readable. R = read-only.
The Write-In-Process (WIP) bit indicates whether the
25AA512 is busy with a write operation. When set to a
‘1’, a write is in progress, when set to a ‘0’, no write is
in progress. This bit is read-only.
The Write Enable Latch (WEL) bit indicates the status
of the write enable latch and is read-only. When set to
a ‘1’, the latch allows writes to the array, when set to a
‘0’, the latch prohibits writes to the array. The state of
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.
FIGURE 2-6:
READ STATUS REGISTER TIMING SEQUENCE (RDSR)
CS
SCK
SI
SO
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Instruction
0 00 00 1 01
High-Impedance
Data from STATUS Register
7 6 54 3 2 10
DS22021F-page 12
 2010 Microchip Technology Inc.