Mixed Radix FFT

Dejan,

The C6670 contains a hardware FFT co-processor (FFTC) that supports the LTE FFTs.  It has the Radix sizes you need.  You can find info on this at:

http://www.ti.com/litv/pdf/sprugs2a

I will also look into the what we have available as far a libraries and 3rd party support for C64x and get back to you.

Regards,

Travis

I'm interested in implementation of mixed radix FFTs on C64x too. Subscribe to this thread and hope to see some good solution. Thanks in advance.

Hi Travis,

Any updates on this?

Br

Anadi

Anadi,

The goal is to get the LTE FFTs added to the DSPLib, but that hasn't happened yet.  I can't give you date at this point, but I'll check into it.

Regards,

Travis

I've heard elsewhere, that target would be C64+. Any hope for C64x?

The plan is for C64x+ and C66x at this time.

Regards,

Travis

Hi Travis,

Thanks for the updates. I was looking for a solution suitable for the 64x+ core. Migration to the c66x core is planned for my design, but not immediately. I guess with the keystone devices such as 6670, this may be required only for some SW special cases, since the FFTC HW accelerator is there. This solution will be really useful for my application.

http://www.ti.com/litv/pdf/sprugs2a can't be found. I'm looking for libraries for LIE FFTs...Does C66X DSPlib contains any ?

Thanks  

The LTE FFTs are not supported in the DSPLIB yet.  The goal is to have them integrated by EOY.

Regards,

Travis

Hi!

As soon as you speak about C66x, take a look on http://www.ti.com/product/tms320c6670. It has FFT coprocessor, which luckily can do LTE FFTs.

Could you give me some suggestions about how to LTE FFTs using FFTC? I'd like to programming at CCSv5 platform. But  I didn't find any info. on how to program. 

Sorry, I could not help much, I am still waiting for evaluation board delivery. Take look on http://www.ti.com/litv/pdf/sprugs2b.

There is an example and test suite in the MCSDK that show you how to program it.  After you install it, look at the following directory:

C:\Program Files\Texas Instruments\pdk_C6670_x_x_x_xx\packages\ti\drv\fftc

http://software-dl.ti.com/sdoemb/sdoemb_public_sw/bios_mcsdk/latest/index_FDS.html

Regards,

Travis

Thank you!

Thank you very much ! I'm downloading MCDSK now!

Is there any FFT benchmark for C66X DSP ?  I saw FFTC benchmark in C6670 at E2E community, but how about C6678 etc , there is no FFTC in them , I want to know the performance of them while computing FFT.

Let me make the concept clear: C6670 has FFTC. It means, there is dedicated hardware on the crystal, which does the job. C6678 has no FFTC, i.e. the is no dedicated hardware to compute FFTs butterflies. In such a case, like with any other DSP one have to compute FFT using DSP's computing pwer, i.e. compute products and accumulate summas. To do this job efficiently TI provides hand optimized library. Unfortunately, that library does not support non power of 2 radices yet. So you could not compute LTE FFTs with C6678 or any other DSP, unless you coded it yourself. We all wait for coming new release for DSP library.

The library the rrlagic mentions is the DSPLIB.  It contains the non-LTE FFT functions.  The documentation associated with it, has the cycle counts for each function.

Regards,

Travis

Thanks  and I 've got the test results of each instruction of C66X , but there is only computing cycles when N=128 and 256 , what about N=512,1024 or even more points ?

The cycle counts of different sizes can be obtained by running unit test provided.  For 3.0.0 release, the unit test (.out file) is in each project folder. For 3.1.0 release, user can open up the project in CCS and build with “release” configuration, and then run the unit test.  FFT cycle formula is not linear. That’s why we don’t provide a formula in the test report. We will look at addressing this in the next release.

Regards,

Travis