vivado FIR Filters

Vivado合成直接从RTL中推导出乘加级联来组成FIR滤波器。这种滤波器有几种可能的实现方式；一个例子是收缩滤波器在7系列DSP48E1 Slice用户指南（UG479）中进行了描述，并在8抽头偶数中显示对称收缩FIR（Verilog）。从编码示例下载编码示例文件。

8-Tap Even Symmetric Systolic FIR (Verilog)

Filename: sfir_even_symetric_systolic_top.v

// sfir_even_symmetric_systolic_top.v

// FIR Symmetric Systolic Filter, Top module is

sfir_even_symmetric_systolic_top

// sfir_shifter - sub module which is used in top level

(* dont_touch = "yes" *)

module sfir_shifter #(parameter dsize = 16, nbtap = 4)

(input clk, [dsize-1:0] datain, output [dsize-1:0] dataout);

(* srl_style = "srl_register" *) reg [dsize-1:0] tmp [0:2*nbtap-1];

integer i;

always @(posedge clk)

begin

tmp[0] <= datain;

for (i=0; i<=2*nbtap-2; i=i+1)

tmp[i+1] <= tmp[i];

end

assign dataout = tmp[2*nbtap-1];

endmodule

// sfir_even_symmetric_systolic_element - sub module which is used in top

module sfir_even_symmetric_systolic_element #(parameter dsize = 16)

(input clk, input signed [dsize-1:0] coeffin, datain, datazin, input signed

[2*dsize-1:0] cascin,

output signed [dsize-1:0] cascdata, output reg signed [2*dsize-1:0]

cascout);

reg signed [dsize-1:0] coeff;

reg signed [dsize-1:0] data;

reg signed [dsize-1:0] dataz;

reg signed [dsize-1:0] datatwo;

reg signed [dsize:0] preadd;

reg signed [2*dsize-1:0] product;

assign cascdata = datatwo;

always @(posedge clk)

begin

coeff <= coeffin;

data <= datain;

datatwo <= data;

dataz <= datazin;

preadd <= datatwo + dataz;

product <= preadd * coeff;

cascout <= product + cascin;

end

endmodule

module sfir_even_symmetric_systolic_top #(parameter nbtap = 4, dsize = 16,

psize = 2*dsize)

(input clk, input signed [dsize-1:0] datain, output signed [2*dsize-1:0]

firout);

wire signed [dsize-1:0] h [nbtap-1:0];

wire signed [dsize-1:0] arraydata [nbtap-1:0];

wire signed [psize-1:0] arrayprod [nbtap-1:0];

wire signed [dsize-1:0] shifterout;

reg signed [dsize-1:0] dataz [nbtap-1:0];

assign h[0] = 7;

assign h[1] = 14;

assign h[2] = -138;

assign h[3] = 129;

assign firout = arrayprod[nbtap-1]; // Connect last product to output

sfir_shifter #(dsize, nbtap) shifter_inst0 (clk, datain, shifterout);

generate

genvar I;

for (I=0; I<nbtap; I=I+1)

if (I==0)

sfir_even_symmetric_systolic_element #(dsize) fte_inst0 (clk, h[I], datain,

shifterout, {32{1'b0}}, arraydata[I], arrayprod[I]);

else

sfir_even_symmetric_systolic_element #(dsize) fte_inst (clk, h[I],

arraydata[I-1], shifterout, arrayprod[I-1], arraydata[I], arrayprod[I]);

endgenerate

endmodule // sfir_even_symmetric_systolic_top

8-Tap Even Symmetric Systolic FIR (VHDL)

Filename: sfir_even_symetric_systolic_top.vhd

--

-- FIR filter top

-- File: sfir_even_symmetric_systolic_top.vhd

-- FIR filter shifter

-- submodule used in top (sfir_even_symmetric_systolic_top)

library ieee;

use ieee.std_logic_1164.all;

entity sfir_shifter is

generic(

DSIZE : natural := 16;

NBTAP : natural := 4

);

port(

clk : in std_logic;

datain : in std_logic_vector(DSIZE - 1 downto 0);

dataout : out std_logic_vector(DSIZE - 1 downto 0)

);

end sfir_shifter;

architecture rtl of sfir_shifter is

-- Declare signals

--

type CHAIN is array (0 to 2 * NBTAP - 1) of std_logic_vector(DSIZE - 1

downto 0);

signal tmp : CHAIN;

begin

process(clk)

begin

if rising_edge(clk) then

tmp(0) <= datain;

looptmp : for i in 0 to 2 * NBTAP - 2 loop

tmp(i + 1) <= tmp(i);

end loop;

end if;

end process;

dataout <= tmp(2 * NBTAP - 1);

end rtl;

--

-- FIR filter engine (multiply with pre-add and post-add)

-- submodule used in top (sfir_even_symmetric_systolic_top)

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

entity sfir_even_symmetric_systolic_element is

generic(DSIZE : natural := 16);

port(clk : in std_logic;

coeffin, datain, datazin : in std_logic_vector(DSIZE - 1 downto 0);

cascin : in std_logic_vector(2 * DSIZE downto 0);

cascdata : out std_logic_vector(DSIZE - 1 downto 0);

cascout : out std_logic_vector(2 * DSIZE downto 0));

end sfir_even_symmetric_systolic_element;

architecture rtl of sfir_even_symmetric_systolic_element is

-- Declare signals

--

signal coeff, data, dataz, datatwo : signed(DSIZE - 1 downto 0);

signal preadd : signed(DSIZE downto 0);

signal product, cascouttmp : signed(2 * DSIZE downto 0);

begin

process(clk)

begin

if rising_edge(clk) then

coeff <= signed(coeffin);

data <= signed(datain);

datatwo <= data;

dataz <= signed(datazin);

preadd <= resize(datatwo, DSIZE + 1) + resize(dataz, DSIZE + 1);

product <= preadd * coeff;

cascouttmp <= product + signed(cascin);

end if;

end process;

-- Type conversion for output

--

cascout <= std_logic_vector(cascouttmp);

cascdata <= std_logic_vector(datatwo);

end rtl;

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

entity sfir_even_symmetric_systolic_top is

generic(NBTAP : natural := 4;

DSIZE : natural := 16;

PSIZE : natural := 33);

port(clk : in std_logic;

datain : in std_logic_vector(DSIZE - 1 downto 0);

firout : out std_logic_vector(PSIZE - 1 downto 0));

end sfir_even_symmetric_systolic_top;

architecture rtl of sfir_even_symmetric_systolic_top is

-- Declare signals

--

type DTAB is array (0 to NBTAP - 1) of std_logic_vector(DSIZE - 1 downto 0);

type HTAB is array (0 to NBTAP - 1) of std_logic_vector(0 to DSIZE - 1);

type PTAB is array (0 to NBTAP - 1) of std_logic_vector(PSIZE - 1 downto 0);

signal arraydata, dataz : DTAB;

signal arrayprod : PTAB;

signal shifterout : std_logic_vector(DSIZE - 1 downto 0);

-- Initialize coefficients and a "zero" for the first filter element

--

constant h : HTAB := ((std_logic_vector(TO_SIGNED(63, DSIZE))),

(std_logic_vector(TO_SIGNED(18, DSIZE))),

(std_logic_vector(TO_SIGNED(-100, DSIZE))),

(std_logic_vector(TO_SIGNED(1, DSIZE))));

constant zero_psize : std_logic_vector(PSIZE - 1 downto 0) := (others =>

'0');

begin

-- Connect last product to output

--

firout <= arrayprod(nbtap - 1);

-- Shifter

--

shift_u0 : entity work.sfir_shifter

generic map(DSIZE, NBTAP)

port map(clk, datain, shifterout);

-- Connect the arithmetic building blocks of the FIR

--

gen : for I in 0 to NBTAP - 1 generate

begin

g0 : if I = 0 generate

element_u0 : entity work.sfir_even_symmetric_systolic_element

generic map(DSIZE)

port map(clk, h(I), datain, shifterout, zero_psize, arraydata(I),

arrayprod(I));

end generate g0;

gi : if I /= 0 generate

element_ui : entity work.sfir_even_symmetric_systolic_element

generic map(DSIZE)

port map(clk, h(I), arraydata(I - 1), shifterout, arrayprod(I - 1),

arraydata(I), arrayprod(I));

end generate gi;

end generate gen;

end rtl;