Entity: ifftmain

Diagram

wire i_clk wire i_reset wire i_ce wire [(2*IWIDTH-1):0] i_sample [(2*OWIDTH-1):0] o_result o_sync

Description

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Filename: ifftmain.v

Project: A General Purpose Pipelined FFT Implementation

Purpose: This is the main module in the General Purpose FPGA FFT implementation. As such, all other modules are subordinate to this one. This module accomplish a fixed size Complex FFT on 64 data points. The FFT is fully pipelined, and accepts as inputs one complex two's complement sample per clock.

Parameters: i_clk The clock. All operations are synchronous with this clock. i_reset Synchronous reset, active high. Setting this line will force the reset of all of the internals to this routine. Further, following a reset, the o_sync line will go high the same time the first output sample is valid. i_ce A clock enable line. If this line is set, this module will accept one complex input value, and produce one (possibly empty) complex output value. i_sample The complex input sample. This value is split into two two's complement numbers, 16 bits each, with the real portion in the high order bits, and the imaginary portion taking the bottom 16 bits. o_result The output result, of the same format as i_sample, only having 16 bits for each of the real and imaginary components, leading to 32 bits total. o_sync A one bit output indicating the first sample of the FFT frame. It also indicates the first valid sample out of the FFT on the first frame.

Arguments: This file was computer generated using the following command line:

    % ./fftgen -v -i -d ../../ifft64 -f 64 -1 -k 1 -p 12 -n 16 -m 16
 This core will use hardware accelerated multiplies (DSPs) for 4 of the 6 stages

Creator: Dan Gisselquist, Ph.D. Gisselquist Technology, LLC

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Copyright (C) 2015-2019, Gisselquist Technology, LLC

This file is part of the general purpose pipelined FFT project.

The pipelined FFT project is free software (firmware): you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

The pipelined FFT project is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. (It's in the $(ROOT)/doc directory. Run make with no target there if the PDF file isn't present.) If not, see http://www.gnu.org/licenses/ for a copy.

License: LGPL, v3, as defined and found on www.gnu.org, http://www.gnu.org/licenses/lgpl.html

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`default_nettype none

Ports

Port name Direction Type Description
i_clk input wire
i_reset input wire
i_ce input wire
i_sample input wire [(2*IWIDTH-1):0]
o_result output [(2*OWIDTH-1):0]
o_sync output

Signals

Name Type Description
br_sync wire Outputs of the FFT, ready for bit reversal.
br_result wire [(2*OWIDTH-1):0]
w_s64 wire A hardware optimized FFT stage
w_d64 wire [31:0]
w_s32 wire A hardware optimized FFT stage
w_d32 wire [31:0]
w_s16 wire A hardware optimized FFT stage
w_d16 wire [31:0]
w_s8 wire A hardware optimized FFT stage
w_d8 wire [31:0]
w_s4 wire
w_d4 wire [31:0]
w_s2 wire
w_d2 wire [31:0]
br_start wire
r_br_started reg

Constants

Name Type Value Description
IWIDTH 16 The bit-width of the input, IWIDTH, output, OWIDTH, and the log of the FFT size. These are localparams, rather than parameters, because once the core has been generated, they can no longer be changed. (These values can be adjusted by running the core generator again.) The reason is simply that these values have been hardwired into the core at several places.
OWIDTH 16 The bit-width of the input, IWIDTH, output, OWIDTH, and the log of the FFT size. These are localparams, rather than parameters, because once the core has been generated, they can no longer be changed. (These values can be adjusted by running the core generator again.) The reason is simply that these values have been hardwired into the core at several places.
LGWIDTH 6 The bit-width of the input, IWIDTH, output, OWIDTH, and the log of the FFT size. These are localparams, rather than parameters, because once the core has been generated, they can no longer be changed. (These values can be adjusted by running the core generator again.) The reason is simply that these values have been hardwired into the core at several places.

Processes

Type: always

Type: always

Type: always

Instantiations

Description
Now for the bit-reversal stage.