10

5167E–SFLSH–5/09

AT25FS010

locked-out sector/block and the corresponding status register control bits are shown in Table 4-5

on page 10.

The six bits, BP0, BP1, BP3, BP4 and WPEN, are nonvolatile cells that have the same proper-

ties and functions as the regular memory cells.

Note:

1. x = don’t care

The WRSR instruction also allows the user to enable or disable the Write Protect (WP) pin

through the use of the Write Protect Enable (WPEN) bit. Hardware write protection is enabled

when the WP pin is low and the WPEN bit is “1”. Hardware write protection is disabled when

either the WP pin is high or the WPEN bit is “0.” When the device is hardware write protected,

writes to the Status Register, including the Block Protect bits and the WPEN bit, and the locked-

out sectors in the memory array are disabled. Write is only allowed to sectors of the memory

which are not locked out. The WRSR instruction is self-timed to automatically erase and pro-

gram BP0, BP1, BP3, BP4 and WPEN bits. In order to write the status register, two separate

instructions must be executed. First, the device must be write enabled via the WREN instruction.

Then, CS must be low and the WRSR instruction and data for the six bits are entered. The

WRSR write cycle will begin once CS goes high. During the internal write cycle, all instructions

will be ignored except RDSR instructions. The AT25FS010 will automatically return to write dis-

able state at the completion of the WRSR cycle. The status register is factory programmed to all

0’s.

Note:

When the WPEN bit is hardware write protected, it cannot be changed back to “0”, as long as the

WP pin is held low.

Table 4-5.

Sector/Block Write Protect Bits

Level

Status Register Bits

AT25FS010

BP4

BP3

BP1

BP0

Array Address

locked Out

Locked-out

Blocks

0(none)

0

000None

None

1(1/32)

0

10001F000H

− 01FFFFH

Sector 8 of Block 4

2(1/16)

1

00001E000H

− 01FFFFH

Sector 7

− 8 of Block 4

3(1/8)

1

10001C000H

− 01FFFFH

Sector 5

− 8 of Block 4

4(1/4)

x

x

0

1

018000H

− 01FFFFH

ALL Sectors of Block 4

5(1/2)

x

x

1

0

010000H

− 01FFFFH

ALL Sectors of Block 3,4

6(ALL)

x

x

1

1

000000H

− 01FFFFH

ALL Sectors of ALL Blocks (1-4)

Table 4-6.

WPEN Operation

WPEN

WP

WEN

ProtectedBlocks

UnprotectedBlocks

Status Register

0

X

0

Protected

Protected

Protected

0

X

1

Protected

Writable

Writable

1

Low

0

Protected

Protected

Protected

1

Low

1

Protected

Writable

Protected

X

High

0

Protected

Protected

Protected

X

High

1

Protected

Writable

Writable