Example For Fft Size N=512; Vertical Fft; Special Product-Number Of Iterations Is N/128 = 4 - Analog Devices SHARC ADSP-214 Series Hardware Reference Manual

FFT Accelerator
The final FFT result is obtained in internal memory, not local memory.

Example for FFT Size N=512

This example shows a large FFT matrix of V × H = 32 × 16.

Vertical FFT

1. Input coeff DMA from vertical coeff buffer[64]
2. Input data DMA from input buffer[1024] (modifier = 2H,
circbuf = 2N)
3. FFT computation
4. Output DMA to special buffer[1024]
Special Product—Number of Iterations is N/128 = 4
1. First iteration:
a. Input coeff DMA from special coeff buffer[512]
b. Input DMA from special buffer[256]
c. FFT computation
d. Output DMA to Special buffer[256]
2. Second iteration:
a. Input coeff DMA from special coeff buffer[512] (offset =
512)
b. Input DMA from special buffer[256] (offset = 256)
c. FFT computation
d. Output DMA to special buffer[256] (offset = 256)
6-12
www.BDTIC.com/ADI
ADSP-214xx SHARC Processor Hardware Reference