CHAPTER 16 DMA CONTROLLER (DMAC)
■ Operation Flowchart for Demand Transfer
- Only requests (level detection) from the external pin (DREQ) are accepted.
Activation by other sources is disabled.
- Access to an external area is required (since access to an external area
becomes the next activation source).
- The number of blocks is always "1", regardless of the settings.
- Interrupt clear and the DMA interrupt are issued when transfer for the
number of times specified is completed.
Figure 16.4-3 Demand Transfer
Load the initial address,
transfer count, and
number of blocks
Calculate the address for
transfer source address access
Calculate the address for transfer
destination address access
Transfer count - 1
Write back the address,
transfer count, and number
DMA transfer end
One-time access for fly-by
Only when the peripheral interrupt
activation source is selected