LM3S5D91 Datasheet, PDF (346/1340 Pages) Texas Instruments – Stellaris® LM3S5D91 Microcontroller

Micro Direct Memory Access (μDMA)
7.2.6.4
Ping-Pong
Ping-Pong mode is used to support a continuous data flow to or from a peripheral. To use Ping-Pong
mode, both the primary and alternate data structures must be implemented. Both structures are set
up by the processor for data transfer between memory and a peripheral. The transfer is started
using the primary control structure. When the transfer using the primary control structure is complete,
the μDMA controller reads the alternate control structure for that channel to continue the transfer.
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 7-2 on page 347 for an example showing operation in Ping-Pong mode.
346
January 22, 2012
Texas Instruments-Production Data