373
CKIO
DRAK
Bus cycle
DREQ
DACK
(RD output)
CPU
CPU
DMAC(W)
DMAC(R)
DMAC(W)
DMAC(R)
CPU
High
High
High
High
3rd sampling is performed,
but since there is no
DREQ
falling edge,
per-cycle sampling starts
2nd sampling is performed,
but since there is no
DREQ
falling edge,
per-cycle sampling starts
1st sampling
2nd sampling
3rd sampling
Note:
When a
DREQ
f
alling edge is detected,
DREQ
m
ust be high f
or at least one cycle bef
ore the sampling point.
Figure 11.19 Cycle-Steal Mode, Edge input (CPU Access: 2 Cycles)
Содержание SH7709S
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Страница 292: ...273 T1 CKIO A25 to A0 CSn RD WR RD D31 to D0 WEn D31 to D0 BS T2 Read Write Figure 10 6 Basic Timing of Basic Interface ...
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