Altera FFT MegaCore Function Bedienungsanleitung PDF herunterladen (Seite 35)

Figure 3-11: FFT Buffered Burst Data Flow Output Flow Control

clk

source_realt

source_imag

source_exp

source_ready

master_source_valid

source_sop

source_eop

EXP0

[0]

[1]

[2]

[3]

[4]

[5]

[6]

[7] X

[8]

[9]

[10]

[0] X

[1]

[2]

[3]

[4]

[5]

[6] X

[7] X

[8]

[9]

[10]

Signals source_sop and source_eop indicate the start-of-packet and end-of-packet for the output block

data respectively.

Note:

You must assert the sink_valid signal for source_valid to be asserted (and a valid data output).

You must leave sink_valid signal asserted at the end of data transfers to extract the final frames of

data from the FFT.

RT** For information about enabling the buffered burst FFT, refer to Enabling the Streaming

FFT.

1. Deassert the system reset.

2. Asserts sink_valid to indicate to the FFT function that valid data is available for input. A successful

data transfer occurs when both the sink_valid and the sink_ready are asserted.

3. Load the first complex data sample into the FFT function and simultaneously asserts sink_sop to

indicate the start of the input block.

4. On the next clock cycle, sink_sop is deasserted and you must load the following N – 1 complex input

data samples in natural order.

5. On the last complex data sample, assert sink_eop.

6. When you load the input block, the FFT function begins computing the transform on the stored input

block. Hold the sink_ready signal high as you can transfer the first few samples of the subsequent

frame into the small FIFO at the input. If this FIFO buffer is filled, the FFT deasserts the sink_ready

signal. It is not mandatory to transfer samples during sink_ready cycles.

3-12

Enabling the Buffered Burst FFT

UG-FFT

2014.12.15

Altera Corporation

FFT IP Core Functional Description

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