H8SSLASH2218 datasheet(247/750 Pages) RENESAS

247 / 750 page

Section 7 DMA Controller (DMAC)

Rev.6.00 Jun. 03, 2008 Page 199 of 698

REJ09B0074-0600

Full Address Mode (Burst Mode): Figure 7.17 shows a transfer example in which

TEND* output

is enabled and word-size full address mode transfer (burst mode) is performed from external 16-

bit, 2-state access space to external 16-bit, 2-state access space.

DMA read

HWR

TEND*

LWR

DMA write DMA read

DMA write DMA read DMA write

DMA

dead

Address bus

Bus release

Last transfer cycle

Burst transfer

Note: * This LSI does not support

TEND output.

Figure 7.17 Example of Full Address Mode (Burst Mode) Transfer

In burst mode, one-byte or one-word transfers are executed consecutively until transfer ends. In the

transfer end cycle (the cycle in which the transfer counter reaches 0), a one-state DMA dead cycle

is inserted after the DMA write cycle.

If a request from another higher-priority channel is generated after burst transfer starts, that

channel has to wait until the burst transfer ends.

If an NMI is generated while a channel designated for burst transfer is in the transfer enabled state,

the DTME bit is cleared and the channel is placed in the transfer disabled state. If burst transfer

has already been activated inside the DMAC, the bus is released on completion of a one-byte or

one-word transfer within the burst transfer, and burst transfer is suspended. If the last transfer

cycle of the burst transfer has already been activated inside the DMAC, execution continues to the

end of the transfer even if the DTME bit is cleared.

Note: * This LSI does not support

TEND output.

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