SST25VF040B View Datasheet(PDF) - Silicon Storage Technology
Part Name
Description
Manufacturer
SST25VF040B Datasheet PDF : 33 Pages
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Data Sheet
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
4 Mbit SPI Serial Flash
SST25VF040B
Program operation, the status register may be read only to
determine the completion of an operation in progress.
Table 3 describes the function of each bit in the software
status register.
TABLE 3: Software Status Register
Bit Name
0 BUSY
1 WEL
2 BP0
3 BP1
4 BP2
5 BP3
6 AAI
7 BPL
Function
1 = Internal Write operation is in progress
0 = No internal Write operation is in progress
1 = Device is memory Write enabled
0 = Device is not memory Write enabled
Indicate current level of block write protection (See Table 4)
Indicate current level of block write protection (See Table 4)
Indicate current level of block write protection (See Table 4)
Indicate current level of block write protection (See Table 4)
Auto Address Increment Programming status
1 = AAI programming mode
0 = Byte-Program mode
1 = BP3, BP2, BP1, BP0 are read-only bits
0 = BP3, BP2, BP1, BP0 are read/writable
Default at
Power-up
0
0
1
1
1
0
0
Read/Write
R
R
R/W
R/W
R/W
R/W
R
0
R/W
T3.0 1295
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.
Auto Address Increment (AAI)
The Auto Address Increment Programming-Status bit pro-
vides status on whether the device is in AAI programming
mode or Byte-Program mode. The default at power up is
Byte-Program mode.
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
• Byte-Program instruction completion
• Auto Address Increment (AAI) programming is
completed or reached its highest unprotected
memory address
• Sector-Erase instruction completion
• Block-Erase instruction completion
• Chip-Erase instruction completion
• Write-Status-Register instructions
©2009 Silicon Storage Technology, Inc.
6
S71295-05-000
10/09
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