/*
 * Design: ECE 274 - Button Debouncer Testbench
 * Author: Roman Lysecky 
 * Copyright 2008, All Rights Reserved
 *
 * Date: March 25, 2008
 *
 * Notes: Incporates Debouncer and DebounceTester_Sim modules
 *
 */
 
`timescale 1us / 1us
module Debouncer_TB();

   parameter ClkPeriod1kHz = 1000;  // 1/1000 us = 1 kHz

   reg Clk1kHz_t, Rst_t, ButtonIn_t;
   wire Debounced_t, Fail_t;
   
   DebounceTester_Sim DebounceTester_0(Clk1kHz_t, Rst_t, Debounced_t, Fail_t);
   Debouncer Debouncer_0(Clk1kHz_t, Rst_t, ButtonIn_t, Debounced_t);

   // Clock Procedure for 1 kHz clock
   // Note: Timescale is in us, not ns
   always begin
      Clk1kHz_t <= 0;
      #(ClkPeriod1kHz/2);
      Clk1kHz_t <= 1;
      #(ClkPeriod1kHz/2);
   end
   
   // Button Input Stimulus Procedure
   initial begin
      ButtonIn_t <= 0;
      // Wait for reset to synchronize
      @(posedge Clk1kHz_t);
      #(10*ClkPeriod1kHz);
      $display("Button Debouncer Test Starting...");
      
      // Simulate debounce event 1
      ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(4*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(20*ClkPeriod1kHz);  // Button Stable
      
      // Simulate debounce event 2
      ButtonIn_t <= 0;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(3*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(20*ClkPeriod1kHz);  // Button Stable

      // Simulate debounce event 3
      ButtonIn_t <= 1;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(3*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(3*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(1*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(20*ClkPeriod1kHz);  // Button Stable

      // Simulate debounce event slow 
      ButtonIn_t <= 0;
      #(3*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(5*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(5*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(7*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(6*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(6*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(3*ClkPeriod1kHz) ButtonIn_t <= 1;
      #(2*ClkPeriod1kHz) ButtonIn_t <= 0;
      #(20*ClkPeriod1kHz);  // Button Stable

      $display("Button Debouncer Test Compelte.");
   end

   // Output Verication Procedure
   initial begin
      // Generate Reset
      Rst_t <= 1;
      @(posedge Clk1kHz_t);
      Rst_t <= 0;
      @(posedge Clk1kHz_t);
      
      while (1==1) begin
         if( Fail_t == 1 ) begin
            $display("Failed Button Debouncer Test at %t.", $time);
            #(ClkPeriod1kHz) $finish;
         end
         #1;
      end
    end
    
endmodule