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Chapter 26 DMA Controller
4.Operation Flowcharts
Figure 4-2 Operation Flowchart for Burst Transfer
■ Demand Transfer
Figure 4-3"Operation Flowchart for Demand Transfer" shows the operation flowchart for demand transfer.
Load the initial address,
transfer count, and
number of blocks
Activation request
wait
DMA transfer end
DMA interrupted
BLK=0
DTC=0
DMA stop
DENB=1
DENB=>0
Write back the address,
transfer count, and number
of blocks
Number of blocks - 1
Interrupt clear
One-time access for fly-by
Reload enable
Only when the peripheral interrupt
activation source is selected
Calculate the address for
transfer source address access
Calculate the address for transfer
destination address access
Transfer count - 1
Interrupt cleared
Burst transfer
- Can be activated by all activation sources (selection).
- Can access to all areas.
- The number of blocks can be set.
- Interrupt clear and the DMA interrupt are issued when
transfer for the number of times specified is completed.