AT26F004 datasheet(22/38 Pages) ATMEL

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3588C–DFLASH–04/06

AT26F004

10.2

Write Status Register

The Write Status Register command is used to modify the SPRL bit of the Status Register.

Before the Write Status Register command can be issued, the Write Enable command must

have been previously issued to set the WEL bit in the Status Register to a logical “1”.

To issue the Write Status Register command, the CS pin must first be asserted and the opcode

of 01h must be clocked into the device. After the opcode has been clocked in, one byte of data

comprised of the SPRL bit value and seven don't care bits must be clocked in. Any additional

data bytes that are sent to the device will be ignored. When the CS pin is deasserted, the SPRL

bit in the Status Register will be modified, and the WEL bit in the Status Register will be reset

back to a logical “0”. The complete one byte of data must be clocked into the device before the

CS# pin is deasserted; otherwise, the device will abort the operation, the state of the SPRL bit

will not change, and the WEL bit in the Status Register will be reset back to the logical “0” state.

If the WP pin is asserted, then the SPRL bit can only be set to a logical “1”. If an attempt is made

to reset the SPRL bit to a logical “0” while the WP pin is asserted, then the Write Status Register

command will be ignored, and the WEL bit in the Status Register will be reset back to the logical

“0” state. In order to reset the SPRL bit to a logical “0”, the WP pin must be deasserted.

Figure 10-2. Write Status Register

SCK

MSB

0000000

410 11

814 15

OPCODE

MSB

XXXXX

STATUS REGISTER IN

HIGH-IMPEDANCE

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