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ADSP-BF535 Complex FFT Demo

Analog Devices, Inc.
DSP Division
Three Technology Way
P.O. Box 9106
Norwood, MA 02062

Date Created:	3/11/02	

This directory contains example ADSP-BF535 program that implements a complex FFT 
routine.

Files contained in this directory:

readme.txt			this file
cfft.dpj			VisualDSP++ 3.0 project file
test_cfft.c			C source file for the fir routine
cfft.vdw			workspace file 
adsp-BF535_C.ldf	linker description file
twiddles.dat		twiddle factors
in.dat				example input data file
out_re.ans			expected real output
out_im.ans			expected imaginary output
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CONTENTS

I.   FUNCTION/ALGORITHM DESCRIPTION
II.  IMPLEMENTATION DESCRIPTION
III. OPERATION DESCRIPTION
IV.  DESCRIPTION OF INPUT DATA         

I. FUNCTION/ALGORITHM DESCRIPTION

The project cfft.dpj contains the implementation of an 8K complex FFT algorithm.
  
II.   IMPLEMENTATION DESCRIPTION

The Blackfin DSP library routine is used to apply the FIR filter.  The twiddle 
factors are stored in twiddles.dat

Note that the twiddle factors can also be derived using the twidfft function 
using from the DSP library.


III.  OPERATION DESCRIPTION

1. Open the VDSP project cfft.dpj in the IDE (Integrated Development 
	Environment).  
2. Under 'Session'->'Select Session', select the ADSP-BF535 ADSP-BLACKFIN Family 
	Platform session.
3. Under 'File'->'Workspace'->'Open', select the cfft.vdw worskpace file. 
4. Under the 'Project' tab, select 'Build Project'.  This will autimatically 
	load the executable.
5. Select 'Run' from the 'Debug' tab on the menu bar.
6. The demo routine performs an 8K FFT.  Please be patient, because the 
	simulator must simulate every hardware memory access.  The output is available 
	in the buffer named _out.  Real and imaginary outputs are interleaved here. 
	Compare these outputs to the file out_re.dat and out_im.dat.  Because of 
	rounding, there may be slight differences between the DSP output and the answer 
	key files.

Note: 1.15 fractional data is used in this example.