LM3S5G31 Datasheet, PDF (366/1223 Pages) Texas Instruments – Stellaris LM3S5G31 Microcontroller

Micro Direct Memory Access (μDMA)
Each time this happens, an interrupt is generated, and the processor can reload the control structure
for the just-completed transfer. Data flow can continue indefinitely this way, using the primary and
alternate control structures to switch back and forth between buffers as the data flows to or from
the peripheral.
Refer to Figure 8-2 on page 366 for an example showing operation in Ping-Pong mode.
Figure 8-2. Example of Ping-Pong μDMA Transaction
µDMA Controller
Primary Structure
SOURCE
DEST
CONTROL
Unused
transfers using BUFFER A
BUFFER A
Cortex-M3 Processor
Peripheral/_{µDMA Interrupt}
Alternate Structure
SOURCE
DEST
CONTROL
Unused
transfers using BUFFER B
BUFFER B
Peripheral/_{µDMA Interrupt}
Primary Structure
SOURCE
DEST
CONTROL
Unused
transfers using BUFFER A
BUFFER A
Peripheral/_{µDMA Interrupt}
Alternate Structure
SOURCE
DEST
CONTROL
Unused
transfers using BUFFER B
BUFFER B
· Process data in BUFFER A
· Reload primary structure
· Process data in BUFFER B
· Reload alternate structure
· Process data in BUFFER B
· Reload alternate structure
366
July 03, 2014
Texas Instruments-Production Data