Analog Devices SHARC ADSP-214 Series - Page 17

ADSP-214xx SHARC Processor Hardware Reference xvii
Contents
Functional Description ............................................................ 6-5
Compute Block ................................................................... 6-5
Data Memory ..................................................................... 6-6
Coefficient Memory ............................................................ 6-6
Accelerator States ................................................................ 6-6
Reset State ...................................................................... 6-6
Idle State ........................................................................ 6-7
Read State ....................................................................... 6-7
Processing State ............................................................... 6-7
Write State ...................................................................... 6-7
Internal Memory Storage ..................................................... 6-8
Small FFT N<=256 ........................................................ 6-8
Large FFT N>=256 ........................................................ 6-9
Operating Modes ................................................................... 6-11
Small FFT Computation (<= 256 Points) .......................... 6-11
Large FFT Computation (>= 512 Points) .......................... 6-11
Example for FFT Size N=512 ............................................ 6-12
Vertical FFT ................................................................. 6-12
Special Product—Number of Iterations is N/128 = 4 ..... 6-12
Horizontal FFT ............................................................. 6-13
No Repeat Mode ............................................................... 6-14
Repeat Mode .................................................................... 6-14
Unpacked Data Mode ...................................................... 6-14
Inverse FFT ...................................................................... 6-15
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