Instructions
M95320, M95640, M95320-x, M95640-x
6.2
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 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.
The Write Enable Latch (WEL) bit, in fact, becomes reset by any of the following events:
■
Power-up
■
■
■
WRDI instruction execution
WRSR instruction completion
WRITE instruction completion.
Figure 8.
Write Disable (WRDI) sequence
S
0
1
2
3
4
5
6
7
C
D
Q
Instruction
High Impedance
AI03750D
16/44
STMICROELECTRONICS [ ST ]
