Micron M25P40 Serial Flash Embedded Memory
READ STATUS REGISTER
WIP Bit
The write in progress (WIP) bit indicates whether the memory is busy with a WRITE
STATUS REGISTER cycle, a PROGRAM cycle, or an ERASE cycle. When the WIP bit is set
to 1, a cycle is in progress; when the WIP bit is set to 0, a cycle is not in progress.
WEL Bit
The write enable latch (WEL) bit indicates the status of the internal write enable latch.
When the WEL bit is set to 1, the internal write enable latch is set; when the WEL bit is
set to 0, the internal write enable latch is reset and no WRITE STATUS REGISTER, PRO-
GRAM, or ERASE command is accepted.
Block Protect Bits
The block protect bits are non-volatile. They define the size of the area to be software
protected against PROGRAM and ERASE commands. The block protect bits are written
with the WRITE STATUS REGISTER command.
When one or more of the block protect bits is set to 1, the relevant memory area, as de-
fined in the Protected Area Sizes table, becomes protected against PAGE PROGRAM and
SECTOR ERASE commands. The block protect bits can be written provided that the
HARDWARE PROTECTED mode has not been set. The BULK ERASE command is execu-
ted only if all block protect bits are 0.
SRWD Bit
The status register write disable (SRWD) bit is operated in conjunction with the write
protect (W#/V
PP
) signal. When the SRWD bit is set to 1 and W#/V
PP
is driven LOW, the
device is put in the hardware protected mode. In the hardware protected mode, the
non-volatile bits of the status register (SRWD, and the block protect bits) become read-
only bits and the WRITE STATUS REGISTER command is no longer accepted for execu-
tion.
PDF: 09005aef8456654f
m25p40.pdf - Rev. Y 8/12 EN
23
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