SH7059 Datasheet, PDF (234/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

10. Direct Memory Access Controller (DMAC)
10.3.5 Dual Address Mode
Dual address mode is used for access of both the transfer source and destination by address. Transfer source and
destination can be accessed either internally or externally. Dual address mode is subdivided into two other modes: direct
address transfer mode and indirect address transfer mode.
Direct Address Transfer Mode: Data is read from the transfer source during the data read cycle, and written to the
transfer destination during the write cycle, so transfer is conducted in two bus cycles. At this time, the transfer data is
temporarily stored in the DMAC. With the kind of external memory transfer shown in figure 10.3, data is read from one of
the memories by the DMAC during a read cycle, then written to the other external memory during the subsequent write
cycle. Figure 10.4 shows the timing for this operation.
1st bus cycle
DMAC
SAR
DAR
Data buffer
Memory
Transfer source
module
Transfer destination
module
The SAR value is taken as the address, and data is read from the transfer source
module and stored temporarily in the DMAC.
2nd bus cycle
DMAC
SAR
DAR
Data buffer
Memory
Transfer source
module
Transfer destination
module
The DAR value is taken as the address, and data stored in the DMAC's data
buffer is written to the transfer destination module.
Figure 10.3 Direct Address Operation in Dual Address Mode
Rev.3.00 Mar. 12, 2008 Page 144 of 948
REJ09B0177-0300