Volatile and Non Volatile Registers
N25Q128 - 1.8 V
6.1
Legacy SPI Status Register
The Status Register contains a number of status and control bits that can be read or set by
specific instructions: Read Status Register (RDSR) and Write Status Register (WRSR). This
is available in all the 3 protocols (Extended SPI, DIO-SPI, and QIO-SPI).
Table 3.
Status register format
b7
b0
SRWD
BP3
TB
BP2
BP1
BP0
WEL
WIP
Status register write protect
Top/bottom bit
Block protect bits
Write enable latch bit
Write in progress bit
6.1.1
6.1.2
WIP bit
The Write In Progress (WIP) bit set to 1 indicates that the memory is busy with a Write
Status Register, Program or Erase cycle. 0 indicates no cycle is in progress.
WEL bit
The Write Enable Latch (WEL) bit set to 1 indicates that the internal Write Enable Latch is
set. When set to 0 the internal Write Enable Latch is reset and no Write Status Register,
Program or Erase instruction is accepted.
6.1.3
BP3, BP2, BP1, BP0 bits
The Block Protect (BP3, BP2, BP1, BP0) bits are non-volatile. They define the size of the
area to be software protected against Program and Erase instructions. These bits are
written with the Write Status Register (WRSR) instruction. When one or more of the Block
Protect (BP3, BP2, BP1, BP0) bits is set to 1, the relevant memory area, as defined in Table
10.: Protected area sizes (TB bit = 0) and Table 11.: Protected area sizes (TB bit = 1),
becomes protected against all program and erase instructions. The Block Protect (BP3,
BP2, BP1, BP0) bits can be written provided that the Hardware Protected mode has not
been set. The Bulk Erase (BE) instruction is executed if, and only if, all Block Protect (BP3,
BP2, BP1, BP0) bits are 0.
6.1.4
TB bit
The Top/Bottom (TB) bit is non-volatile. It can be set and reset with the Write Status Register
(WRSR) instruction provided that the Write Enable (WREN) instruction has been issued.
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