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ML674001 Series/ML675001 Series User’s Manual
Chapter 12
Direct Memory Access Controller (DMAC)
12-22
12.4
DMA Transfer Timing
12.4.1
Starting a Transfer
At least five clock cycles elapse between a transfer request and the actual start of the DMA transfer.
(1) Bus access for cycle stealing mode with auto request
Transfer request (autoreq*1)
…
Bus access
…
(2) Bus access for cycle stealing mode with external requests
Transfer request (DREQ)
…
DREQCLR output
…
Final transfer start signal (TCOUT)
…
Bus access
…
(3) Bus access for burst mode with external requests
Transfer request (DREQ)
…
DREQCLR output
…
Final transfer start signal (TCOUT)
…
Bus access
…
CPU
DMA(R)
DMA(W)
CPU
DMA(R)
CPU
DMA(W)
CPU
DMA(R)
DMA(W)
DMA(R)
DMA(W)
DMA(R)
DMA(W)
DMA(R)
DMA(W)
CPU
DMA(R)
DMA(W)
CPU
DMA(R)
CPU
DMA(R)
DMA(W)
CPU
*1.
Setting a bit in the DMA transfer mode register (DMACTMOD0 or DMACTMOD1) for the channel
automatically generates this internal transfer request signal.
*2.
The DMA controller uses dual address mode.
Figure 12.1 Transfer Start Timing