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FFT Time-to-Frequency TMS320C5000 DSP Code

Description: this routine performs the tasks involved in FFT spectral analysis ie a complete time-to-frequency FFT on an N = 2ˆM time sample array in one call. Between 4-point and 32768-point FFTs may be performed, the upper limit depending on data-memory availability. The FFT decimates in time, the computations being done in place with full intermediate scaling and 0.5lsb rounding.
         Routine calls are provided for: zeroing the FFT array, pre-computing the "twiddle factors", performing the FFT, and converting the output spectra real and imag parts to magnitudes. Optionally, the FFT computation may be done on: real and imag time samples or on real samples only, both with pre-stored twiddle factors, or on real and imag time samples with twiddle factors calculated on-the-fly. These options give various trade-offs between cycles taken, data memory required, and program memory used.
         In the assembler interface, the code is re-entrant so multiple channels in one DSP can readily be processed. A C-callable wrapper can also be provided. A comprehensive user's guide together with example application files are provided with the code. Test results are available.

Processor Load:

FFT mode setting N-point Cycles# Data memory (words) Prog memory (words)#
Re,Im samples, pre-stored twiddle factors 16 640 48 244
256 14744 768
4096 323808 12288
Re-only samples, pre-stored twiddle factors 16 418 48 295
256 11762 768
4096 276666 12288
Re, Im samples, twiddle factors computed 16 1394 32 231
256 27278 512
4096 524522 8192

- #figures for assembler interfaces with TMS320C54x operation

Availability: NOW, sale is under licence - integration support offered

 
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