Datasheet

M95640, M95320
14/42
Write Enable (WREN)
The Write Enable Latch (WEL) bit must be set pri-
or to each WRITE and WRSR instruction. The only
way to do this is to send a Write Enable instruction
to the device.
As shown in Figure 8., to send this instruction to
the device, Chip Select (S
) is driven Low, and the
bits of the instruction byte are shifted in, on Serial
Data Input (D). The device then enters a wait
state. It waits for a the device to be deselected, by
Chip Select (S
) being driven High.
Figure 8. Write Enable (WREN) Sequence
Write Disable (WRDI)
One way of resetting the Write Enable Latch
(WEL) bit is to send a Write Disable instruction to
the device.
As shown in Figure 9., to send this instruction to
the device, Chip Select (S
) is driven Low, and the
bits of the instruction byte are shifted in, on Serial
Data Input (D).
The device then enters a wait state. It waits for a
the device to be deselected, by Chip Select (S
) be-
ing driven High.
The Write Enable Latch (WEL) bit, in fact, be-
comes reset by any of the following events:
– Power-up
– WRDI instruction execution
– WRSR instruction completion
– WRITE instruction completion.
Figure 9. Write Disable (WRDI) Sequence
C
D
AI02281E
S
Q
21 34567
High Impedance
0
Instruction
C
D
AI03750D
S
Q
21 34567
High Impedance
0
Instruction