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Chapter 7
DMA Functions (DMA Controller)
Preliminary User’s Manual U15839EE1V0UM00
7.5.4 Block transfer mode
In the block transfer mode, once transfer begins, the DMAC continues the transfer operation without
releasing the bus until a terminal count occurs. No other DMA requests are acknowledged during block
transfer.
After the block transfer ends and the DMAC releases the bus and another DMA transfer can be
acknowledged.
Figure 7-26, “Block Transfer Example,” on page 192 shows a block transfer mode example. It is a block
transfer mode example in which a higher priority DMA transfer request is generated. DMA channels 2
and 3 are used for the block transfer example.
Figure 7-26:
Block Transfer Example
DMA Transfer
Request CH2
DMA Transfer
Request CH3
DMA channel 3
terminal count
DMA3
CPU
DMA3
DMA2 DMA2 DMA2
CPU
CPU
CPU
DMA3 DMA3
DMA3
DMA3
DMA3 DMA3
DMA2 DMA2
The bus is always released
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