A25L40PT-F AMICC [AMIC Technology], A25L40PT-F Datasheet - Page 12

• Manufacturer Part Number: A25L40PT-F
• Description: 4 Mbit, Low Voltage, Serial Flash Memory With 85MHz SPI Bus Interface
• Manufacturer: AMICC [AMIC Technology]

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 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 6.
Table 4. Status Register Format
The status and control bits of the Status Register are as
follows:
WIP bit. The Write In Progress (WIP) 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.
Figure 6. Read Status Register (RDSR) Instruction Sequence and Data-Out Sequence
PRELIMINARY
Status Register
SRWD
Write Protect
b7
C
D
S
Q
0
(May, 2007, Version 0.4)
0
0 1
High Impedance
Block Protect Bits
BP2
Write Enable Latch Bit
2 3 4
Instruction
BP1
Write In Progress Bit
BP0 WEL WIP
5 6
7
MSB
7
8
b0
Status Register Out
6
9
5
10
4
11 12 13 14 15
11
3
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 1.) 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.
SRWD bit. The Status Register Write Disable (SRWD) bit is
operated in conjunction with the Write Protect (
The Status Register Write Disable (SRWD) bit and Write
Protect (
Protected mode (when the Status Register Write Disable
(SRWD) bit is set to 1, and Write Protect (
In this mode, the non-volatile bits of the Status Register
(SRWD, BP2, BP1, BP0) become read-only bits and the Write
Status Register (WRSR) instruction is no longer accepted for
execution.
2
1
0
W
MSB
) signal allow the device to be put in the Hardware
7
Status Register Out
6
5
4
AMIC Technology Corp.
3
2
1
A25L40P Series
0
7
W
) is driven Low).
W
) signal.