SH7706 Datasheet, PDF (327/749 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7700 Series

Section 9 Direct Memory Access Controller (DMAC)
• Single Address Mode
In the single address mode, either the transfer source or transfer destination external device is
accessed (selected) by means of the DACK signal, and the other device is accessed by address.
In this mode, the DMAC performs one DMA transfer in one bus cycle, accessing one of the
external devices by outputting the DACK transfer request acknowledge signal to it, and at the
same time outputting an address to the other device involved in the transfer. For example, in
the case of transfer between external memory and an external device with DACK, as shown in
figure 9.11, when the external device outputs data to the data bus, that data is written to the
external memory in the same bus cycle.
SH7706
External address bus External data bus
DMAC
External
memory
External device
with DACK
DACK
DREQ
Data flow
Figure 9.11 Data Flow in the Single Address Mode
Two kinds of transfer are possible in the single address mode: (1) transfer between an external
device with DACK and a memory-mapped external device, and (2) transfer between an external
device with DACK and external memory. In both cases, only the external request signal (DREQ)
is used for transfer requests.
Rev. 5.00 May 29, 2006 page 279 of 698
REJ09B0146-0500