Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 409

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Circular Buffer DMA

Logical channels operate in circular buffer DMA mode when the channel

mode select bits in the

available for synchronous channels only. In contrast to ping-pong buffer-

ing, circular buffering uses a single, circular memory buffer to process

channel data.

For circular buffer mode, synchronous data is handled in the following

• Before buffer processing can begin, the

grammed with the beginning and the ending address of the circular

buffer. Set the

• At the start of buffer processing, the beginning address of the circu-

lar buffer (

Additionally, the ending address of the circular buffer (

loaded into the

• During the processing of the circular buffer, the

updated to indicate which quadlet of the synchronous data is cur-

rently being processed.

• Once the end of the buffer is reached and

reloaded to point to the beginning address of the circular buffer

Unlike in ping-pong DMA, the

of the circular buffer DMA. Software must clear this bit to halt buffer pro-

For more information, see "Programming Model" on page 8-16.

ADSP-214xx SHARC Processor Hardware Reference

www.BDTIC.com/ADI

) is loaded into

bit field of the

bit remains set during the processing

Media Local Bus

field of the

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