Dsp Dma Programming Guidelines; Transfer Source And Destination; Transfer Start - Texas Instruments OMAP5912 Reference Manual

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Table 127. Channel Destination Frame Index Registers (DMA_CDFI0...DMA_CDFI5)

Destination frame index Channel destination frame index

DSP DMA Programming Guidelines

Contains the channel source element index,

expressed in bytes, which is used to compute the

addresses when double-indexed addressing mode

Note: When GSCR[0] = 1, DESTINA-

TION_FRAME_INDEX= DMA_CDFI.

When GSCR[0] = 0, DESTINA-

TION_FRAME_INDEX= DMA_CSFI. For

double-index addressing mode.

This section discusses the DSP DMA programming guidelines.

In the DSP, the DMA is able to transfer data between the MPUI, the EMIF (and

thus external memories), the TIPB bridge, the SARAM, and the DARAM. It

includes five ports and six independent channels. This means that up to six

DMA transfers can run simultaneously. Each channel has a set of dedicated

registers and a global register.

There are two ways to start a DMA transfer:

Software start (software request): After setting up the configuration

registers of a DMA channel, the processor activates the transfer in this

channel by writing the DMA_CCR.EN bit of this channel. The transfer

immediately begins.

Hardware start (hardware request): The processor sets up a DMA channel

and designates it as a synchronized transfer (demand-driven by DMA

requests from the external DMA). The channel then waits for a DMA

request to start transferring. Each time the DMA requests this channel, an

amount of data is transferred. This amount of data can be:

A complete element transferred in response to a DMA request

A complete frame of several elements transferred in response to a

Direct Memory Access (DMA) Support

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