FPGAExercise6code

Shift Register

//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

Shift Register Testbench

 
//
// 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

Linear Feedback Shift Register

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

LFSR Testbench

//
// 	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

Timescale

//
// filename timescale.v
//
`timescale 1ns / 10ps