W25Q80 Datasheet, PDF (23/61 Pages) Winbond – 8M-BIT, 16M-BIT AND 32M-BIT SERIAL FLASH MEMORY WITH DUAL AND QUAD SPI

W25Q80, W25Q16, W25Q32
10.2.7 Write Status Register (01h)
The Write Status Register instruction allows the Status Register to be written. A Write Enable instruction
must previously have been executed for the device to accept the Write Status Register Instruction
(Status Register bit WEL must equal 1). Once write enabled, the instruction is entered by driving /CS
low, sending the instruction code “01h”, and then writing the status register data byte as illustrated in
figure 7. The Status Register bits are shown in figure 3 and described earlier in this datasheet.
Only non-volatile Status Register bits SRP0, SEC, TB, BP2, BP1, BP0 (bits 7, 5, 4, 3, 2 of Status
Register-1) and QE, SRP1(bits 9 and 8 of Status Register-2) can be written to. All other Status Register
bit locations are read-only and will not be affected by the Write Status Register instruction.
The /CS pin must be driven high after the eighth or sixteenth bit of data that is clocked in. If this is not
done the Write Status Register instruction will not be executed. If /CS is driven high after the eighth
clock (compatible with the 25X series) the QE and SRP1 bits will be cleared to 0. After /CS is driven
high, the self-timed Write Status Register cycle will commence for a time duration of tW (See AC
Characteristics). While the Write Status Register cycle is in progress, the Read Status Register
instruction may still be accessed to check the status of the BUSY bit. The BUSY bit is a 1 during the
Write Status Register cycle and a 0 when the cycle is finished and ready to accept other instructions
again. After the Write Register cycle has finished the Write Enable Latch (WEL) bit in the Status
Register will be cleared to 0.
The Write Status Register instruction allows the Block Protect bits (SEC, TB, BP2, BP1 and BP0) to be
set for protecting all, a portion, or none of the memory from erase and program instructions. Protected
areas become read-only (see Status Register Memory Protection table and description). The Write
Status Register instruction also allows the Status Register Protect bits (SRP0, SRP1) to be set. Those
bits are used in conjunction with the Write Protect (/WP) pin, Lock out or OTP features to disable writes
to the status register. Please refer to 10.1.16 for detailed descriptions regarding Status Register
protection methods. Factory default for all status Register bits are 0.
Figure 7. Write Status Register Instruction Sequence Diagram
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Publication Release Date: September 26, 2007
Preliminary - Revision B