W77E058A40DL Datasheet, PDF (41/87 Pages) Nuvotem Talema – GENERAL DESCRIPTION

W77E058A
from 0 to 7, resulting in MOVX instructions that last from 2 to 9 machine cycles in length. Note that the
stretching of 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
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
M0
MACHINE
CYCLES
RD OR WR
STROBE WIDTH
IN CLOCKS
RD OR WR
STROBE
WIDTH @ 25
MHZ
RD OR WR
STROBE
WIDTH @ 40
MHZ
0
2
2
80 nS
50 nS
1
3 (default)
4
160 nS
100 nS
0
4
8
320 nS
200 nS
1
5
12
480 nS
300 nS
0
6
16
640 nS
400 nS
1
7
20
800 nS
500 nS
0
8
24
960 nS
600 nS
1
9
28
1120 nS
700 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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Publication Release Date: April 17, 2007
Revision A10