User manual

Functional Description

www.ti.com

12.3.6.3 Auto Mode

Auto mode is similar to basic mode, except that when a transfer request is received, the transfer

completes, even if the μDMA request is removed. This mode is suitable for software-triggered transfers.

Generally, auto mode is not used with a peripheral.

The μDMA controller sets the mode for that channel to stop when all the items have been transferred

using auto mode.

12.3.6.4 Ping-Pong

Ping-pong mode is used to support a continuous data flow to or from a peripheral. Both the primary and

alternate data structures must be implemented to use ping-pong mode. 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 completes, the μDMA controller

reads the alternate control structure for that channel to continue the transfer. Each time this occurs, 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

between buffers as the data flows to or from the peripheral.

Figure 12-2 shows an example operation in ping-pong mode.

1042

Micro Direct Memory Access (µDMA) SWCU117A–February 2015–Revised March 2015

Submit Documentation Feedback