Subversion Repositories mcip_open

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-- Company:        Ferhat Abbas University - Algeria
-- Engineer:       Ibrahim MEZZAH
-- Progect Supervisor: Dr H. Chemali
-- Create Date:    14:24:19 06/01/05
-- Design Name:    Reset device
-- Module Name:    Rest_module - reset
-- Project Name:   Microcontroller IP (MCIP)
-- Target Device:  xc3s500e-4fg320
-- Tool versions:  Xilinx ISE 9.1.03i
-- Description:	 This module generate the global reset of the device (nreset).
--						 nreset is active (low) if one of following events occure:
--						 soft reset, stack overflow, Watchdog time out, external reset.
-- Revision: 		 07/09/2008
-- Revision 3 - Extend a soft reset time.
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library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
 
entity reset_module is
    Port ( clock				: in std_logic;
           nExternal_reset	: in std_logic;
			  Soft_reset		: in std_logic;
           WDT_reset			: in std_logic;
           Stack_reset		: in std_logic;
           nreset				: out std_logic);
end reset_module;
 
architecture reset of reset_module is
	constant reset_counter_length : integer := 5;
	signal reset_enable : std_logic;
	signal reset_counter : std_logic_vector(reset_counter_length downto 1);
	signal disable_counter_value : std_logic_vector(reset_counter_length downto 1);
begin
 
	disable_counter_value <= (others => '1');
 
	Enabling_reset : process(nExternal_reset, clock, reset_counter,
									 disable_counter_value, Soft_reset, WDT_reset,
									 Stack_reset)
	begin
	  if nExternal_reset = '0' then
		 reset_enable <= '0';
	  else
		 if clock'event and clock = '1' then
			if reset_counter = disable_counter_value then
				reset_enable <= '0';
			else
				if Soft_reset = '1' or WDT_reset = '1' or Stack_reset = '1' then
					reset_enable <= '1';
				else
					reset_enable <= reset_enable;
				end if;
			end if;
		 else
			reset_enable <= reset_enable;
		 end if;
	  end if;
	end process;
 
	Counter : process(reset_enable, clock)
	begin
	  if reset_enable = '0' then
		 reset_counter <= (others => '0');
	  else
		 if clock'event and clock = '1' then
			reset_counter <= reset_counter + "1";
		 else
			reset_counter <= reset_counter;
		 end if;
	  end if;
	end process;
 
	nreset <= '0' when ( nExternal_reset = '0' or reset_enable = '1') else
				 '1';
 
end reset;