Renesas SH7641 - Manual (Page 455)

Section 13 Direct Memory Access Controller (DMAC)
Rev. 4.00 Sep. 14, 2005 Page 405 of 982
REJ09B0023-0400
Section 13 Direct Memory Access Controller (DMAC)
This LSI includes the 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, on-chip
memory, memory-mapped external devices, and on-chip peripheral modules.
Figure 13.1 shows a block diagram of the DMAC.
13.1 Features
• Four channels (Two channels can receive an external request)
• 4-Gbyte physical address space
• Data transfer unit is selectable: Byte, word (two bytes), longword (four bytes), and 16 bytes
(longword
× 4)
• Maximum transfer count: 16,777,216 transfers (24 bits)
• Address mode: Dual address mode and single address mode are supported.
• Transfer requests
 External request
 On-chip peripheral module request
 Auto request
The following modules can issue an on-chip peripheral module request.
 SCIF0, SCIF1, SCIF2, MTU0, MTU1, MTU2, MTU3, MTU4, USB, CMT0, CMT1, A/D
converter 0, A/D converter 1
• Selectable bus modes
 Cycle steal mode (normal mode and intermittent mode)
 Burst mode
• Selectable channel priority levels: The channel priority levels are selectable between fixed
mode and round-robin mode.
• Interrupt request: An interrupt request can be generated to the CPU at the end of the specified
counts of data transfer.
• External request detection: There are following four types of DREQ input detection.
 Low level detection
 High level detection
 Rising edge level detection
 Falling edge level detection