Figure 9-3. Memory Scatter-Gather, Setup and Configuration
NOTES:
1. Application has a need to copy data items from three separate locations in memory into one combined buffer.
2. Application sets up
µ
DMA “task list” in memory, which contains the pointers and control configuration for three
µ
DMA copy “tasks.”
3. Application sets up the channel primary control structure to copy each task configuration, one at a time, to the
alternate control structure, where it is executed by the
µ
DMA controller.
4. The SRC and DST pointers in the task list must point to the last location in the corresponding buffer.
C
4 WORDS (SRC A)
16 WORDS (SRC B)
SRC
DST
ITEMS=16
Unused
SRC
DST
ITEMS=1
1 WORD (SRC C)
4 (DEST A)
16 (DEST B)
1 (DEST C)
DST
A
B
“TASK” A
“TASK” B
“TASK” C
SRC
DST
ITEMS=12
SRC
DST
ITEMS=n
Task List in Memory
2
1
3
Source and Destination
Buffer in Memory
Channel Control
Table in Memory
Channel Primary
Control Structure
Channel Alternate
Control Structure
Unused
ITEMS=4
SRC
Unused
June 18, 2014
688
Texas Instruments-Production Data
Micro Direct Memory Access (μDMA)