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W25Q64BV
Publication Release Date: July 08, 2010
- 13 - Revision E
11. CONTROL AND STATUS REGISTERS
The Read Status Register-1 and Status Register-2 instructions can be used to provide status on the
availability of the Flash memory array, if the device is write enabled or disabled, the state of write
protection and the Quad SPI setting. The Write Status Register instruction can be used to configure the
devices write protection features and Quad SPI setting. Write access to the Status Register is controlled by
the state of the non-volatile Status Register Protect bits (SRP0, SRP1), the Write Enable instruction, and
in some cases the /WP pin.
11.1 STATUS REGISTER
11.1.1 BUSY
BUSY is a read only bit in the status register (S0) that is set to a 1 state when the device is executing a
Page Program, Sector Erase, Block Erase, Chip Erase or Write Status Register instruction. During this
time the device will ignore further instructions except for the Read Status Register and Erase Suspend
instruction (see t
W, tPP, tSE, tBE, and tCE in AC Characteristics). When the program, erase or write status
register instruction has completed, the BUSY bit will be cleared to a 0 state indicating the device is ready
for further instructions.
11.1.2 Write Enable Latch (WEL)
Write Enable Latch (WEL) is a read only bit in the status register (S1) that is set to a 1 after executing a
Write Enable Instruction. The WEL status bit is cleared to a 0 when the device is write disabled. A write
disable state occurs upon power-up or after any of the following instructions: Write Disable, Page
Program, Sector Erase, Block Erase, Chip Erase and Write Status Register.
11.1.3 Block Protect Bits (BP2, BP1, BP0)
The Block Protect Bits (BP2, BP1, BP0) are non-volatile read/write bits in the status register (S4, S3, and
S2) that provide Write Protection control and status. Block Protect bits can be set using the Write Status
Register Instruction (see t
W in AC characteristics). All, none or a portion of the memory array can be
protected from Program and Erase instructions (see Status Register Memory Protection table). The
factory default setting for the Block Protection Bits is 0, none of the array protected.
11.1.4 Top/Bottom Block Protect (TB)
The non-volatile Top/Bottom bit (TB) controls if the Block Protect Bits (BP2, BP1, BP0) protect from the
Top (TB=0) or the Bottom (TB=1) of the array as shown in the Status Register Memory Protection table.
The factory default setting is TB=0. The TB bit can be set with the Write Status Register Instruction
depending on the state of the SRP0, SRP1 and WEL bits.
11.1.5 Sector/Block Protect (SEC)
The non-volatile Sector protect bit (SEC) controls if the Block Protect Bits (BP2, BP1, BP0) protect 4KB
Sectors (SEC=1) or 64KB Blocks (SEC=0) in the Top (TB=0) or the Bottom (TB=1) of the array as shown
in the Status Register Memory Protection table. The default setting is SEC=0.