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Alternate structure
Primary structure
Primary structure
Alternate structure
Transfer continues using alternate
BUFFER B
BUFFER A
x Process data in BUFFER A
x Reload primary structure
Transfers using BUFFER A
BUFFER A
Transfers using BUFFER B
Transfer continues using alternate
Transfer continues using primary
BUFFER B
Transfers using BUFFER B
Peripheral or
µ
DMA interrupt
x Process data in BUFFER B
x Reload alternate structure
x Process data in BUFFER A
x Reload alternate structure
µDMA controller
Cortex-M3 processor
Time
Peripheral or
µ
DMA interrupt
Peripheral or
µDMA interrupt
SOURCE
DEST
CONTROL
Unused
SOURCE
DEST
CONTROL
Unused
SOURCE
DEST
CONTROL
Unused
SOURCE
DEST
CONTROL
Unused
Transfers using BUFFER A
www.ti.com Functional Description
Figure 12-2. Example of Ping-Pong μDMA Transaction
12.3.6.5 Memory Scatter-Gather Mode
Memory scatter-gather mode is a complex mode used when data must be transferred to or from varied
locations in memory instead of a set of contiguous locations in a memory buffer. For example, a gather
μDMA operation could be used to selectively read the payload of several stored packets of a
communication protocol, and store them together in sequence in a memory buffer.
1043
SWCU117A–February 2015–Revised March 2015 Micro Direct Memory Access (µDMA)
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