H8SSLASH2224 datasheet(345/1071 Pages) RENESAS

345 / 1071 page

Section 8 DMA Controller (DMAC)

Rev. 5.00 Aug 08, 2006 page 259 of 982

REJ09B0054-0500

DMA

read

Address bus

LWR

TEND

HWR

Bus release

DMA

write

DMA

dead

DMA

read

DMA

write

DMA

read

DMA

write

Bus release

Burst transfer

Last transfer cycle

Figure 8.21 Example of Full Address Mode Transfer (Burst Mode)

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 interrupt is generated while a channel designated for burst transfer is in the transfer

enabled state, the DTME bit in DMABCRL 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.

Full Address Mode (Block Transfer Mode): Figure 8.22 shows a transfer example in which

TEND output is enabled and word-size full address mode transfer (block transfer mode) is

performed from internal 16-bit, 1-state access space to external 16-bit, 2-state access space.

H8S/2224 Scheda tecnica(PDF) 345 Page - Renesas Technology Corp