Step 6. (Optional) Download and Build the FFTW Library

FFTW (Fastest Fourier Transform in the West) is a C subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine transforms or DCT/DST). See the FFTW home page for more information on this library.

The FFTW library is required for the sig_analyzer example and/or if you want to use FFT functions in an embedded application.

Version 3.3.4 is the latest stable release of FFTW, and full source code can be downloaded here. Assuming that the tar file is downloaded to ~/Downloads, use the following commands to untar and build the FFTW library. These commands assume that the TI SDK is installed in the following directory: /opt/ti-sdk-am335x-evm-07.00.00.00

# cd /opt/ti-sdk-am335x-evm-07.00.00.00/example-applications
# tar -xzvf ~/Downloads/fftw-3.3.4.tar.gz
# cd fftw-3.3.4/
# ./configure --with-slow-timer --host=arm-linux-gnueabi --enable-single --enable-neon CFLAGS="-march=armv7-a -marm -mthumb-interwork -mfloat-abi=hard -mfpu=neon -mtune=cortex-a8 -O4 -Wall" CC="/opt/ti-sdk-am335x-evm-07.00.00.00/linux-devkit/sysroots/i686-arago-linux/usr/bin/arm-linux-gnueabihf-gcc"
# make

Notes: The above steps will build fftw-3.3.4/.libs/libfftw3f.a supporting single-precision floating point. Therefore, the single precision APIs in FFTW library must be used rather than the default double precision APIs.

If you install the FFTW library in a directory other than example-applications, you must reference this path when building the signal analyzer example.