
Figure 8-14 shows the timing when the DMAC is activated by low input at a
DREQ
pin. This
example shows a word-size transfer from a 16-bit two-state access area to another 16-bit two-state
access area. The DMAC continues the transfer while the
DREQ
pin is held low.
Figure 8-14 Bus Timing of DMA Transfer Requested by Low
DREQ
Input
ø
DREQ
RD
HWR
TEND
T
1
T
2
T
3
T
d
T
1
T
2
T
1
T
2
T
1
T
2
T
d
T
1
T
2
T
1
T
2
T
1
T
2
LWR
,
CPU cycle
DMAC cycle
CPU cycle
DMAC cycle
(last transfer cycle)
CPU cycle
Source
address
Destination
address
Source
address
Destination
address
Address
bus
226
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