M95040, M95020, M95010
Write to Memory Array (WRITE)
given address to the end of the same page can be
programmed in a single instruction.
If Chip Select (S) still continues to be driven Low,
the next byte of input data is shifted in, and is used
to overwrite the byte at the start of the current
page.
As shown in Figure 13., to send this instruction to
the device, Chip Select (S) is first driven Low. The
bits of the instruction byte, address byte, and at
least one data byte are then shifted in, on Serial
Data Input (D).
The instruction is terminated by driving Chip Se-
lect (S) High after the rising edge of Serial Clock
(C) that latches the last data bit, and before the
next rising edge of Serial Clock (C) occurs any-
where on the bus. In the case of Figure 13., this
occurs after the eighth bit of the data byte has
been latched in, indicating that the instruction is
being used to write a single byte. The self-timed
The instruction is not accepted, and is not execut-
ed, under the following conditions:
–
if the Write Enable Latch (WEL) bit has not
been set to 1 (by executing a Write Enable
instruction just before)
–
–
if a Write cycle is already in progress
if the device has not been deselected, by Chip
Select (S) being driven High, at a byte
boundary (after the rising edge of Serial Clock
(C) that latches the last data bit, and before
the next rising edge of Serial Clock (C) occurs
anywhere on the bus)
Write cycle starts, and continues for a period t
WC
(as specified in Table 18. to Table 22.), at the end
of which the Write in Progress (WIP) bit is reset to
0.
If, though, Chip Select (S) continues to be driven
Low, as shown in Figure 14., the next byte of input
data is shifted in. In this way, all the bytes from the
–
if Write Protect (W) is Low or if the addressed
page is in the region protected by the Block
Protect (BP1 and BP0) bits.
Figure 13. Byte Write (WRITE) Sequence
S
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
C
Instruction
A8
Byte Address
Data Byte
1
A7 A6 A5 A4 A3 A2 A1 A0
7
6
5
4
3
2
0
D
Q
High Impedance
AI01442D
Note: Depending on the memory size, as shown in Table 6., the most significant address bits are Don’t Care.
17/37
STMICROELECTRONICS [ ST ]
