SH7727 Datasheet, PDF (484/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 14 Direct Memory Access Controller (DMAC)
• Single Address Mode
The single address mode is used when transfer is performed between external devices including
external memories, one of which is accessed (selected) by the DACK signal and the other of
which is accessed by address. In this mode, the DMAC outputs the transfer request acknowledge
signal DACK to one external device, and simultaneously outputs an address to the other device;
thus DMA transfer is performed in one bus cycle. An example of transfer between an external
memory and an external device with DACK is shown in figure 14.11. The external device outputs
data to a data bus and the data is written to the external memory in a single bus cycle.
SH7727
External address bus External data bus
DMAC
External
memory
External device
with DACK
DACK
DREQ
Data flow
Figure 14.11 Data Flow in Single Address Mode
Two kinds of transfer are possible in 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 an external memory. In both cases, only the external request signal (DREQ) is
used as a transfer request.
Figures 14.12 and 14.13 show examples of the DMA transfer timing in single address mode.
Rev. 5.00 Dec 12, 2005 page 412 of 1034
REJ09B0254-0500