AT25DF041B datasheet(28/64 Pages) RENESAS

28 / 64 page

DS-AT25DF041B-040 Rev. H

Page 28

12/13/22

AT25DF041B Datasheet

When writing to the Status Register, bits 5, 4, 3, and 2 are not modified but are decoded by the device for the

purposes of the Global Protect and Global Unprotect functions. Only bit 7, the SPRL bit, is modified. Thus, when

reading the Status Register, bits 5, 4, 3, and 2 do not reflect the values written to them but, instead, indicate the

status of the WP pin and the sector protection status. See the “Read Status Register” section and Table 9 on page

33 for details on the Status Register format and what values can be read for bits 5, 4, 3, and 2.

9.6

Read Sector Protection Registers

The Sector Protection Registers can be read to determine the current software protection status of each sector.

Reading the Sector Protection Registers, however, does not determine the status of the WP pin.

To read the Sector Protection Register for a particular sector, the CS pin must first be asserted and the opcode of

3Ch must be clocked in. Once the opcode has been clocked in, three address bytes designating any address

within the sector must be clocked in. After the last address byte has been clocked in, the device begins outputting

data on the SO pin during every subsequent clock cycle. The data being output are a repeating byte of either FFh

or 00h to denote the value of the appropriate Sector Protection Register.

Deasserting the CS pin terminate the read operation and put the SO pin into a high-impedance state. The CS pin

can be deasserted at any time and does not require that a full byte of data be read.

In addition to reading the individual Sector Protection Registers, the Software Protection Status (SWP) bit in the

Status Register can be read to determine if all, some, or none of the sectors are software protected (see Section

11, Status Register Commands, on page 33, for more details).

Figure 22. Read Sector Protection Register

Table 5. Read Sector Protection Register – Output Data

Output Data

Sector Protection Register Value

00h

Sector Protection Register value is 0 (sector is unprotected).

FFh

Sector Protection Register value is 1 (sector is protected).

SCK

MSB

00111100

410 11

37 38

31 32

29 30

3940

OPCODE

AAAA

AAA

MSBMSB

DDDDDDD

ADDRESS BITS A23-A0

DATA BYTE

HIGH-IMPEDANCE

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