W77C32F-40 Nuvoton Technology Corporation of America, W77C32F-40 Datasheet - Page 39

• Manufacturer Part Number: W77C32F-40
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W77C32F-40

• Lead Free Status / Rohs Status: Supplier Unconfirmed

If CNT = 50
Clock cycles in W77C32 = (12 + (15 * 50)) * 4 = (12 + 750) * 4 = 3048
We can see that in the first program the standard 8032 takes 15720 cycles, while the W77C32 takes
only 5240 cycles for the same code. In the second program, written for the W77C32, program
execution requires only 3048 clock cycles. If the size of the block is increased then the saving is even
greater.
9.3 External Data Memory Access Timing
The timing for the MOVX instruction is another feature of the W77C32. In the standard 8032, the
MOVX instruction has a fixed execution time of 2 machine cycles. However in the W77C32, the
duration of the access can be varied by the user.
The instruction starts off as a normal op-code fetch of 4 clocks. In the next machine cycle, the
W77C32 puts out the address of the external Data Memory and the actual access occurs here. The
user can change the duration of this access time by setting the STRETCH value. The Clock Control
SFR (CKCON) has three bits that control the stretch value. These three bits are M2-0 (bits 2-0 of
CKCON). These three bits give the user 8 different access time options. The stretch can be varied
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
0
0
0
0
1
1
1
1
M1
0
0
1
1
0
0
1
1
M0
0
1
0
1
0
1
0
1
3 (default)
MACHINE
CYCLES
2
4
5
6
7
8
9
STROBE WIDTH IN
RD
CLOCKS
OR
12
16
20
24
28
2
4
8
WR
- 39 -
Publication Release Date: December 20, 2005
STROBE WIDTH
RD
@25 MHZ
1120 nS
160 nS
320 nS
480 nS
640 nS
800 nS
960 nS
80 nS
OR
W77C32/W77C032
WR
STROBE WIDTH
RD
@40 MHZ
100 nS
200 nS
300 nS
400 nS
500 nS
600 nS
700 nS
50 nS
OR
Revision A5
WR