/*
 * Design: ECE 274 - Button Debouncer Test Circuit for Simulation
 * Author: Roman Lysecky 
 * Copyright 2008, All Rights Reserved
 *
 * Date: March 25, 2008
 *
 */
 
`timescale 1us / 1us
module DebounceTester_Sim(Clk, Rst, Debounced, Fail);

   input Clk, Rst;
   input Debounced;
   output reg Fail;
 
   reg lDebounced, diff;
   reg [3:0] tCnt;
   reg iFail;
   
   // Reg1 Procedure
   always @(posedge Clk) begin
      if (Rst == 1) lDebounced <= 0;
      else lDebounced <= Debounced;
   end
   
   // Diff Procedure
   always @(Debounced, lDebounced) begin
      diff <= Debounced ^ lDebounced;
   end
   
   // Timer Procedure
   always @(posedge Clk) begin
      if (Rst == 1) tCnt <= 0;
      else if (diff == 1) tCnt <= 0;   
      else if (tCnt != 4'hF) tCnt <= tCnt + 1;
      else tCnt <= tCnt;
   end   

   // Debounce Tester Procedure
   always @(posedge Clk) begin
      if (Rst == 1) begin
         iFail <= 0;
         Fail <= 0;
      end
      else if (iFail == 1) begin
         iFail <= 1;   
         Fail <= 1;   
      end
      else if (diff == 1 && tCnt < 10 ) begin
         iFail <= 1;   
         Fail <= 1;
      end
      else begin
         iFail <= 0;
         Fail <= 0;
      end
   end   
endmodule