ADSP-2126x SHARC Processor Hardware Reference
7-9
I/O Processor
parameters to the index, modify, and count registers, then set the DMA
enable bit to re-enable DMA.
Chained DMA
. Chained DMA sequences are a set of multiple DMA
operations, each autoinitializing the next in line. To start a new DMA
sequence after the current one is finished, the IOP automatically loads
new index, modify, and count values from an internal memory location
pointed to by that channel’s chain pointer (
CP
) register. Using chaining,
programs can set up consecutive DMA operations and each operation can
have different attributes.
Chaining is only supported on the SPI and SPORT DMA chan-
nels. The parallel port, and IDP port do not support chaining.
In general, a DMA sequence starts when one of the following occurs:
• Chaining is disabled, and the DMA enable bit transitions from low
to high.
• Chaining is enabled, DMA is enabled, and the chain pointer regis-
ter address field is written with a nonzero value. In this case, TCB
chain loading of the channel parameter registers occurs first.
• Chaining is enabled, the chain pointer register address field is non-
zero, and the current DMA sequence finishes. Again, TCB chain
loading occurs.
A DMA sequence ends when one of the following occurs:
• The count register decrements to zero, and the
CP
register is zero.
• Chaining is disabled and the channel’s DMA enable bit transitions
from high to low. If the DMA enable bit goes low (=0) and chain-
ing is enabled, the channel enters chain insertion mode and the
DMA sequence continues.
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...