This Data Sheet may be revised by subsequent versions

©2004 Eon Silicon Solution, Inc., www.essi.com.tw

or modifications due to changes in technical specifications.

11

EN25P16

Rev. C, Issue Date: 2006/12/25

Read Status Register (RDSR) (05h)

The Read Status Register (RDSR) instruction allows the Status Register to be read. The Status Register

may be read at any time, even while a Program, Erase or Write Status Register cycle is in progress.

When one of these cycles is in progress, it is recommended to check the Write In Progress (WIP) bit

before sending a new instruction to the device. It is also possible to read the Status Register continuously,

as shown in Figure 7.

Table 6. Status Register Bit Locations

The status and control bits of the Status Register are as follows:

BUSY bit. The BUSY bit indicates whether the memory is busy with a Write Status Register, Program or

Erase cycle. When set to 1, such a cycle is in progress, when reset to 0 no such cycle is in progress.

WEL bit. The Write Enable Latch (WEL) bit indicates the status of the internal Write Enable Latch. When

set to 1 the internal Write Enable Latch is set, when set to 0 the internal Write Enable Latch is reset and

no Write Status Register, Program or Erase instruction is accepted.

BP2, BP1, BP0 bits. The Block Protect (BP2, BP1, BP0) bits are non-volatile. They define the size of the

area to be software protected against Program and Erase instructions. These bits are written with the

Write Status Register (WRSR) instruction. When one or both of the Block Protect (BP2, BP1, BP0) bits is

set to 1, the relevant memory area (as defined in Table 3.) becomes protected against Page Program (PP)

and Sector Erase (SE) instructions. The Block Protect (BP2, BP1, BP0) bits can be written provided that

the Hardware Protected mode has not been set. The Bulk Erase (BE) instruction is executed if, and only if,

both Block Protect (BP2, BP1, BP0) bits are 0.

Reserved bit. Status register bit locations 5 and 6 are reserved for future use. Current devices will read 0

for these bit locations. It is recommended to mask out the reserved bit when testing the Status Register.

Doing this will ensure compatibility with future devices.

SRP bit. The Status Register Protect (SRP) bit is operated in conjunction with the Write Protect (WP#)

signal. The Status Register Write Protect (SRP) bit and Write Protect (WP#) signal allow the device to be

put in the Hardware Protected mode (when the Status Register Protect (SRP) bit is set to 1, and Write

Protect (WP#) is driven Low). In this mode, the non-volatile bits of the Status Register (SRP, BP2, BP1,

BP0) become read-only bits and the Write Status Register (WRSR) instruction is no longer accepted for

execution.