Section 9 Direct Memory Access Controller (DMAC)
Rev. 5.00 May 29, 2006 page 251 of 698
REJ09B0146-0500
Section 9 Direct Memory Access Controller (DMAC)
This chip includes a four-channel direct memory access controller (DMAC). The DMAC can be
used in place of the CPU to perform high-speed transfers between external devices that have
DACK (transfer request acknowledge signal), external memory, memory-mapped external
devices, and on-chip peripheral modules (SCIF, A/D converter, and D/A converter). Using the
DMAC reduces the burden on the CPU and increases overall operating efficiency.
Figure 9.1 shows a block diagram of the DMAC.
9.1
Feature
The DMAC has the following features.
•
Four channels
•
Address space: Architecturally 4-Gbytes
•
8-bit, 16-bit, 32-bit, or 16-byte transfer (In 16-byte transfer, four 32-bit reads are executed,
followed by four 32-bit writes.)
•
Maximum transfer counter: 16 Mbytes (16777216 transfers)
•
Supports dual address mode
Direct address transfer mode: The values specified in the DMAC registers indicates the
transfer source and transfer destination. Two bus cycles are required for one data transfer.
Indirect address transfer mode: Data is transferred with the address stored prior to the
address specified in the transfer source address in the DMAC. Other operations are the
same as those of direct address transfer mode. This function is only valid in channel 3. Four
bus cycles are required for one data transfer.
•
Supports single address mode
Either the transfer source or transfer destination peripheral device is accessed (selected) by
means of the DACK signal, and the other device is accessed by address. One bus cycle is
required for one data transfer.
•
Channel functions: Transfer mode that can be specified is different in each channel.
Channel 0: External request can be accepted.
Channel 1: External request can be accepted.
Channel 2: This channel has a source address reload function, which reloads a source
address for each 4 transfers.
Channel 3: In this channel, direct address transfer mode or indirect address transfer mode
can be specified.
Содержание SH7706 Series
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Страница 160: ...Section 5 Cache Rev 5 00 May 29 2006 page 112 of 698 REJ09B0146 0500 ...
Страница 370: ...Section 11 Watchdog Timer WDT Rev 5 00 May 29 2006 page 322 of 698 REJ09B0146 0500 ...
Страница 532: ...Section 16 Serial Communication Interface with FIFO SCIF Rev 5 00 May 29 2006 page 484 of 698 REJ09B0146 0500 ...
Страница 554: ...Section 17 Pin Function Controller PFC Rev 5 00 May 29 2006 page 506 of 698 REJ09B0146 0500 ...
Страница 576: ...Section 18 I O Ports Rev 5 00 May 29 2006 page 528 of 698 REJ09B0146 0500 ...
Страница 614: ...Section 21 User Debugging Interface H UDI Rev 5 00 May 29 2006 page 566 of 698 REJ09B0146 0500 ...
Страница 746: ...Index Rev 5 00 May 29 2006 page 698 of 698 REJ09B0146 0500 ...
Страница 749: ...SH7706 Group Hardware Manual ...