FPGAExercise6code
From HacDC Wiki
Shift Register
<pre> //filename sr.v `include "timescale.v"
module sr(D, Q, Q_regs, clk, rst); parameter Ndepth=4; parameter TP=1;
input D, clk, rst; output Q; output [Ndepth-1:0] Q_regs;
reg [Ndepth-1:0] Q_regs;
assign Q = Q_regs[Ndepth-1];
/* This is a comment block Hi Elliot This works fine! */
always@(posedge clk) if(rst) Q_regs <= #TP 0; //This is a comment else Q_regs <= #TP {Q_regs[Ndepth-2:0],D}; endmodule </pre>
Shift Register Testbench
<pre> // // filename sr_tb.v // // Exercise 6 // FPGA Workshop - HacDC // Group think // `include "timescale.v" module sr_tb(); // Parameters
parameter CLKPERIOD = 20; // 50Mhz w/ 1ns time increments parameter FINISHTIME = 1000;
// DUT INPUTS
reg D; reg clk; reg rst;
// DUT OUTPUTS wire Q; wire [3:0] Q_regs;
// Misc reg finish;
// Event defitions event reset;
// DUT Instantiation // shift(.D(), .Q(), .Q_regs(), .clk(), .rst()); sr DUT(.D(D), .Q(Q), .Q_regs(Q_regs), .clk(clk), .rst(rst));
// -------- // Stimulus // --------
// Clk Generation always #(CLKPERIOD/2) clk = ~clk; // Initial Conditions initial begin D = 0; rst = 0; clk = 1; finish = 0; // Wait to end the simulation #FINISHTIME $display("============================="); $display("I'm done now!"); $display("Finished at time %5d", $time); $finish; end
// Inputs initial begin #1 -> reset; //event calls like to occur after some //period of time wait(finish); finish = 0; repeat (5) #CLKPERIOD; D=1; wait (Q); #CLKPERIOD D=1; #CLKPERIOD D=0; #CLKPERIOD D=1; #CLKPERIOD D=0; repeat (5) #CLKPERIOD;
$display("================"); $display("End of Stimulus"); $display("Finishing at time %5d", $time); $finish;
end
// Event defitions always @(reset) begin $display ("Resetting the Registers"); #(CLKPERIOD/2) rst = 1; #CLKPERIOD rst = 0; finish = 1; end
// Monitor initial begin $dumpfile ("waves.lxt"); $dumpvars(0,sr_tb); end
endmodule </pre>
Linear Feedback Shift Register
<pre> module lfsr(Q, Q_regs, clk, rst); // x^5+x^3+1 parameter N=5; parameter Tp=1; input clk, rst; output Q; output [N-1:0] Q_regs; reg [N-1:0] Q_regs; assign Q = Q_regs[0]; always@(posedge clk) if(rst) Q_regs<= #Tp 5'b1; else Q_regs<= #Tp {Q_regs[3], Q_regs[2], Q_regs[1], Q_regs[0], Q_regs[4]^Q_regs[2]}; endmodule </pre>
LFSR Testbench
<pre> // // Exercise 6 // FPGA Workshop - HacDC // Group think // `include "timescale.v" module lfsr_tb(); // Parameters
parameter CLKPERIOD = 20; // 50Mhz w/ 1ns time increments parameter FINISHTIME = 2*1000;
// DUT INPUTS
reg clk; reg rst;
// DUT OUTPUTS wire Q; wire [4:0] Q_regs;
// Misc reg finish;
// Event defitions event reset;
// DUT Instantiation // lfsr(.Q(), .Q_regs(), .clk(), .rst()); lfsr DUT(.Q(Q), .Q_regs(Q_regs), .clk(clk), .rst(rst));
// -------- // Stimulus // --------
// Clk Generation always #(CLKPERIOD/2) clk = ~clk; // Initial Conditions initial begin rst = 0; clk = 1; finish = 0; // Wait to end the simulation #FINISHTIME $display("============================="); $display("I'm done now!"); $display("Finished at time %5d", $time); $finish; end
// Inputs initial begin #1 -> reset; //event calls like to occur after some //period of time wait(finish); finish = 0; repeat (62) #CLKPERIOD; $display("================"); $display("End of Stimulus"); $display("Finishing at time %5d", $time); $finish;
end
// Event defitions always @(reset) begin $display ("Resetting the Registers"); #(CLKPERIOD/2) rst = 1; #CLKPERIOD rst = 0; finish = 1; end
// Monitor initial begin $dumpfile ("waves.lxt"); $dumpvars(0,lfsr_tb); end
endmodule </pre>
Timescale
<pre> // // filename timescale.v // `timescale 1ns / 10ps </pre>