IPR-FFT Altera, IPR-FFT Datasheet - Page 42

• Manufacturer Part Number: IPR-FFT
• Description: IP CORE Renewal Of IP-FFT
• Manufacturer: Altera
• Type: MegaCorer

Specifications of IPR-FFT

• Software Application: IP CORE, DSP Filters And Transforms
• Supported Families: Arria GX, Cyclone, HardCopy, Stratix
• Features: Bit-Accurate MATLAB Models, Radix-4 And Mixed Radix-4/2 Implementations
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Function: Fast Fourier Transform Processor
• License: Renewal License
• Lead Free Status / RoHS Status: na
• Lead Free Status / RoHS Status: na

3–8
Figure 3–5. FFT Streaming Data Flow Architecture Output Flow Control
Variable Streaming
FFT MegaCore Function User Guide
exponent_out
source_ready
source_imag
source_valid
source_real
source_eop
source_sop
clk
To change direction on a block-by-block basis, assert or deassert inverse
(appropriately) simultaneously with the application of the sink_sop pulse
(concurrent with the first input data sample of the block).
When the FFT has completed the transform of the input block, it asserts source_valid
and outputs the complex transform domain data block in natural order. The FFT
function asserts source_sop to indicate the first output sample.
the output flow control.
After N data transfers, source_eop is asserted to indicate the end of the output data
block
Enabling the Streaming FFT
The sink_valid signal must be asserted for source_valid to be asserted (and a
valid data output). To extract the final frames of data from the FFT, you need to
provide several frames where the sink_valid signal is asserted and apply the
sink_sop and sink_eop signals in accordance with the Avalon-ST specification.
The variable streaming architecture allows continuous streaming of input data and
produces a continuous stream of output data similar to the streaming architecture.
Change the Block Size
You change the size of the FFT on a block-by-block basis by changing the value of the
fftpts simultaneously with the application of the sink_sop pulse (concurrent with
the first input data sample of the block). fftpts uses a binary representation of the
size of the transform, therefore for a block with maximum transfer size of 1,024.
Table 3–2
Table 3–2. fftpts and Transform Size
(Figure 3–3 on page
shows the value of the fftpts signal and the equivalent transform size.
10000000000
01000000000
00100000000
00010000000
00001000000
fftpts
X r [0]
X i [0]
X r [1]
X i [1]
3–7).
X r [2]
X i [2]
X r [3]
X i [3]
X r [4]
X i [4]
X i [5]
X r [5]
X r [6]
X i [6]
EXP0
X r [7]
X i [7]
© December 2010 Altera Corporation
Transform Size
X r [8]
X i [8]
Chapter 3: Functional Description
1,024
512
256
128
64
X r [9]
X i [9]
Figure 3–5
I/O Data Flow Architectures
X r [10] X r [11] X r [12]
X i [10]
X i [11]
shows
X i [12]