LE25LA322

No.NA1310-9/14

2-2. Status Register Write (WRSR)

The information in status registers BP0, BP1, and SRWP can be rewritten using the status register write command.

RDY, WEN, bit4, bit5, and bit6 are read-only bits and cannot be rewritten. The information in bits BP0, BP1, and

SRWP is stored in the non-volatile memory, and when it is written in these bits, the contents are retained even at

power-down.

“Figure 6 Status Register Write” shows the timing waveforms of status register write, and Figure 11 shows a status

register write flowchart. Consisting of the first and second bus cycles, the status register write command initiates the

internal write operation at the rising CS edge after the data has been input following (01h). By the operation of this

command, the information in bits BP0, BP1, and SRWP can be rewritten. Since bits RDY (bit0), WEN (bit1), bit4, bit5,

and bit6 of the status register cannot be written, no problem will arise if an attempt is made to set them to any value

when rewriting the status register. Status register write ends can be detected by RDY of status register read. Information

in the status register can be rewritten 1,000 times (min.). To initiate status register write, the logic level of the WP pin

must be set high and the status register WEN must be set to “1”.

Figure 6 Status Register Write

01

2 3 4 5 6

7 8

15

Mode3

tWPS

8CLK

Hight Impedance

DATA

tWPH

Self-timed

Write Cycle

tSRW

01h

Mode0

CS

WP

SCK

SI

SO

(00000001)

2-3. Contents of Each Status Register

RDY (bit0)

Ready/Busy detection

The RDY register is for detecting the write end. When it is “1”, the device is in a busy state, and when it is “0”, it means

that the write operation is completed.

WEN (bit1)

Write enable

The WEN register is for detecting whether the device can perform write operations. If it is set to “0”, the device will not

perform the write operation even if the write command is input. If it is set to “1”, the device can perform write operation

in any area that is not block-protected.

WEN can be controlled using the write enable and write disable commands. By inputting the write enable command

(06h), WEN can be set to “1”, and by inputting the write disable command (04h), it can be set to “0”. In the following

states, WEN is automatically set to “0” in order to protect against unintentional writing.

• At power-on

• Upon completion of write

• Upon completion of status register write

∗ If a write operation has not been performed inside the device because, for instance, the command input for any of the

write operations has failed or a write operation has been performed for a protected address, WEN will retain the status

established prior to the issue of the command concerned. Furthermore, its state will not be changed by a read operation.