Data Sheet

64 Mbit SPI Serial Dual I/O Flash

SST25VF064C

7

©2010 Silicon Storage Technology, Inc.

S71392-04-000

04/10

Status Register

The software status register provides status on whether the

flash memory array is available for any Read or Write oper-

ation, whether the device is Write enabled, and the state of

the Memory Write protection. During an internal Erase or

Program operation, the status register may be read only to

determine the completion of an operation in progress.

Table 4 describes the function of each bit in the software

status register.

Busy

The Busy bit determines whether there is an internal Erase

or Program operation in progress. A ‘1’ for the Busy bit indi-

cates the device is busy with an operation in progress. A ‘0’

indicates the device is ready for the next valid operation.

Write Enable Latch (WEL)

The Write-Enable-Latch bit indicates the status of the inter-

nal memory Write Enable Latch. If the Write-Enable-Latch

bit is set to ‘1’, it indicates the device is Write enabled. If the

bit is set to ‘0’ (reset), it indicates the device is not Write

enabled and does not accept any memory Write (Program/

Erase) commands. The Write-Enable-Latch bit is automati-

cally reset under the following conditions:

•

Power-up

•

Write-Disable (WRDI) instruction completion

•

Write-Status Register instruction completion

•

Page-Program instruction completion

•

Dual-Input Page-Program instruction completion

•

Sector-Erase instruction completion

•

Block-Erase instruction completion

•

Chip-Erase instruction completion

•

Program SID instruction completion

•

Lockout SID instruction completion

TABLE

4: Status Register

Bit

Name

Function

Default at

Power-up

Read/Write

0

BUSY

1 = Internal Write operation is in progress

0 = No internal Write operation is in progress

0R

1

WEL

1 = Device is memory Write enabled

0 = Device is not memory Write enabled

0R

2

BP0

Indicate current level of block write protection (See Table 5)

1

R/W

3

BP1

Indicate current level of block write protection (See Table 5)

1

R/W

4

BP2

Indicate current level of block write protection (See Table 5)

1

R/W

5

BP3

Indicate current level of block write protection (See Table 5)

1

R/W

6

1. The Security ID status will always be ‘1’ at power-up after a successful execution of the Lockout SID instruction; otherwise, the

default at power up is ‘0’.

Security ID status

1 = Security ID space locked

0 = Security ID space not locked

01

R

7

BPL

1 = BP3, BP2, BP1, BP0 are read-only bits

0 = BP3, BP2, BP1, BP0 are readable/writable

0R/W

T4.0 1392