
FFT Accelerator
6-14
ADSP-214xx SHARC Processor Hardware Reference
No Repeat Mode
If the
FFT_RPT
bit = 0, after
FFT_START
= 1 the accelerator moves from the
idle state into the read state (input DMA). After the read completes, the
accelerator moves into the processing state then the write state to read the
results back into internal memory. The accelerator ends in the idle state.
For large FFTs (based on the
VDIM
,
HDIM
and
NOVER256
bits) the accelerator
knows when the entire FFT processing has finished.
Repeat Mode
If the
FFT_RPT
bit = 1, after
FFT_START
= 1 the accelerator moves from the
idle state into the read state (input DMA). After the read completes, the
accelerator moves into the processing state then the write state to read the
results back into internal memory. The accelerator then moves automati-
cally back into the read state for the next FFT frame. In this state multiple
linked TCBs which were executed during the first iteration are re-used.
For large FFTs (based on the configuration of the
VDIM
,
HDIM
and
NOVER256
bits) the accelerator knows when the entire frame processing has
finished in order to re-load the new FFT frame parameters at the right
time.
Unpacked Data Mode
For small FFTs (FFT<=256), the unpacked data mode can be selected
independently for the input or output streams through the use of the
FFT_CPACKIN
or
FFT_CPACKOUT
bits (
FFTCTL2
register).
The
FFT_CPACKIN
/
FFT_CPACKOUT
settings are not applicable for N
3
512 points. The input is always expected to be in alternate real and
imaginary format and the output is always generated in the same
format.
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Summary of Contents for SHARC ADSP-214 Series
Page 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...