HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 468

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

11.1
A two-channel direct memory access controller (DMAC) is included on-chip. The DMAC can be
used in place of the CPU to perform high-speed data transfers between external devices equipped
with DACK (transfer request acknowledge signal), external memories, on-chip memory, and
memory-mapped external devices. Using the DMAC reduces the burden on the CPU and increases
the operating efficiency of the chip as a whole.
11.1.1
The DMAC has the following features:
Two channels
Address space: Architecturally 4 Gbytes
Choice of data transfer unit: Byte, word (2-byte), longword (4-byte) or 16-byte unit (In a 16-
byte transfer, four longword reads are executed, followed by four longword writes.)
Maximum of 16,777,216 (16M) transfers
In the event of a cache hit, CPU instruction processing and DMA operation can be executed in
parallel
Single address mode transfers: Either the transfer source or transfer destination (peripheral
device) is accessed by a DACK signal (selectable) while the other is accessed by address. One
transfer unit of data is transferred in one bus cycle.
Possible transfer devices: External devices with DACK and memory-mapped external devices
(including external memory)
Dual address mode transfer: Both the transfer source and transfer destination are accessed by
address. One transfer unit of data is transferred in two bus cycles.
Possible transfer devices:
Section 11 Direct Memory Access Controller (DMAC)
Two external memories
External memory and memory-mapped external device
Two memory-mapped external devices
External memory and on-chip peripheral module
Memory-mapped external device and on-chip peripheral module
Two on-chip peripheral modules
On-chip memory and memory-mapped external device
Two on-chip memories
On-chip memory and on-chip peripheral modules
On-chip memory and external memory
Overview
Features
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