M35B32 datasheet(19/44 Pages) STMICROELECTRONICS

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M35B32

Instructions

6.4

Read Status Register (RDSR)

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 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 10.

The value read by the RDSR instruction depends on the logical signal applied on the W

input pin:

•

if W=0: Status Register = [0, 0, 0, 0, 0, 0, WEL, WIP]

•

if W=1: Status Register = [0, 0, BP3, BP2, BP1, BP0, WEL, WIP]

The status bits of the Status Register are as follows:

6.4.1

WIP bit

The Write In Progress (WIP) bit indicates whether the memory is busy with a Write, Program

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

in progress.

6.4.2

WEL bit

The WEL bit is set to 1 after decoding a WREN instruction. When the WEL bit is set to 1, a

Write, Program or Erase instruction is executed; when set to 0, a Write, Program or Erase

instruction is not executed.

The WEL bit is reset to 0 after the completion of a Write, Program or Erase instruction,

unless when /W is driven low when addressing the Event sector (see table4).

BP3

BP2

BP1

BP0

WEL(1)

1. WEL and WIP are volatile read-only bits (WEL is set and reset by specific instructions; WIP is

automatically set and reset by the internal logic of the device).

WIP(1)

EEPROM bits

RAM bits

Table 4. Value of the WEL bit after decoding a Page Write, Page Program, Page

Erase or Sector Erase instruction

Targeted M35B32 sector

W input = 0

W input = 1

Data sector: (16-N) pages(1)

1. N is defined with BPi bits and (0 < N < 15): Page = 256 bytes.

WEL is reset to 0

Event sector: N pages(1)

WEL is not reset

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