SH7014 datasheet(200/754 Pages) RENESAS

200 / 754 page

9. Direct Memory Access Controller (DMAC)

Rev.5.00 Sep. 27, 2007 Page 166 of 716

REJ09B0398-0500

Address Modes

Single Address Mode: In the single address mode, both the transfer source and destination are

external; one (selectable) is accessed by a DACK signal while the other is accessed by an address.

In this mode, the DMAC performs the DMA transfer in 1 bus cycle by simultaneously outputting a

transfer request acknowledge DACK signal to one external device to access it while outputting an

address to the other end of the transfer. Figure 9.3 shows an example of a transfer between an

external memory and an external device with DACK in which the external device outputs data to

the data bus while that data is written in external memory in the same bus cycle.

DMAC

DACK

DREQ

External

memory

External device

with DACK

This LSI

External address bus

: Data flow

External data bus

Figure 9.3 Data Flow in Single Address Mode

Two types of transfers are possible in the single address mode: (a) transfers between external

devices with DACK and memory-mapped external devices, and (b) transfers between external

devices with DACK and external memory. The only transfer requests for either of these is the

external request (

DREQ). Figure 9.4 shows the DMA transfer timing for the single address mode.

SH7014 Datasheet(PDF) 200 Page - Renesas Technology Corp