W77IE58 Datasheet, PDF (46/90 Pages) Winbond – 8-BIT MICROCONTROLLER

Preliminary W77IE58
the instruction only results in the elongation of the MOVX instruction, as if the state of the CPU was held
for the desired period. There is no effect on any other instruction or its timing. By default, the Stretch
value is set at 1, giving a MOVX instruction of 3 machine cycles. If desired by the user the stretch value
can be set to 0 to give the fastest MOVX instruction of only 2 machine cycles.
Table 4. Data Memory Cycle Stretch Values
M2
M1
M0
Machine
Cycles
RD or WR strobe
width in Clocks
RD or WR strobe
width @ 25 MHz
0
0
0
2
2
0
0
1
3(default)
4
0
1
0
4
8
0
1
1
5
12
1
0
0
6
16
1
0
1
7
20
1
1
0
8
24
1
1
1
9
28
80 nS
160 nS
320 nS
480 nS
640 nS
800 nS
960 nS
1120 nS
CLK
ALE
PSEN
WR
PORT 0
PORT 2
Last Cycle
of Previous
Instruction
First
Machine cycle
Second
Machine cycle
MOVX instruction cycle
Next Instruction
Machine Cycle
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
A0-A7
D0-D7
A0-A7
D0-D7
A0-A7
D0-D7
A0-A7
D0-D7
MOVX Inst.
Address
Next Inst.
Address
MOVX Data
Address
MOVX Inst.
Next Inst. Read ^{MOVX Data out}
A15-A8
A15-A8
A15-A8
A15-A8
Figure 8. Data Memory Write with Stretch Value = 0
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