TC1796
System Units (Vol. 1 of 2)
Direct Memory Access Controller
User’s Manual 12-4 V2.0, 2007-07
DMA, V2.0
12.1.2 Definition of Terms
DMA Move
A DMA move is an operation that always consists of two parts:
1. A read move that loads data from a data source into the DMA controller
2. A write move that puts data from the DMA controller to a data destination
Within a DMA move, data is always moved from the data source via the DMA controller
to the data destination. Data is temporarily stored in the DMA controller. The data width
of read move and write move are always identical (8-bit, 16-bit or 32-bit). Data assembly
or disassembly is not supported.
Figure 12-2 DMA Definition of Terms
DMA Transfer
A DMA transfer can be composed of 1, 2, 4, 8 or 16 DMA moves.
DMA Transaction
A DMA transaction is composed of several (at least one) DMA transfers. The Transfer
Count determines the number of DMA transfers within one DMA transaction.
Example:
1024 word (32-bit wide) transactions can be composed of 256 transfers of four DMA
word moves, or 128 transfers of eight DMA word moves.
MCA05681
Data
Destination
DMA Controller
Read
Move
Write
Move
DMA Move
Data
Source
DMA
Channel
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