Altera FFT MegaCore Function - Manual (Page 34)

Figure 3-9: Data Flow—Engine with Bit-Reversal or Digit-Reversal Mode
clk
reset_n
sink_valid
sink_ready
sink_sop
sink_eop
sink_real
sink_imag
source_real
source_imag
source_valid
source_sop
source_eop
Buffered Burst
The buffered burst I/O data flow FFT requires fewer memory resources than the streaming I/O data flow
FFT, but the tradeoff is an average block throughput reduction.
Enabling the Buffered Burst FFT
Figure 3-10: FFT Buffered Burst Data Flow Input Flow Control
clk
reset_n
sink_valid
sink_ready
sink_sop
inverse
sink_real
sink_imag
xr(0) xr(1) xr(2) xr(3) xr(4) xr(5) xr(6) xr(7) xr(8) xr(9)
xi(0) xi(1) xi(2) xi(3) xi(4) xi(5) xi(6) xi(7) xi(8) xi(9)
1. Following the interval of time where the FFT processor reads the input samples from an internal input
buffer, it re-asserts
sink_ready
indicating it is ready to read in the next input block. Apply a pulse on
sink_sop
aligned in time with the first input sample of the next block to indicate the beginning of the
subsequent input block.
2. As in all data flows, the logical level of inverse for a particular block is registered by the FFT at the time
when you assert the start-of-packet signal,
sink_sop
.
When the FFT completes the transform of the input block, it asserts the
source_valid
and outputs the
complex transform domain data block in natural order .
UG-FFT
2014.12.15
Buffered Burst 3-11
FFT IP Core Functional Description Altera Corporation
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