univibrator.vhd

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--**************************************************************
--*                                                            *
--*     The source code for the ATLAS BCM "AAA" FPGA is made   *
--*     available via the GNU General Public License (GPL)     *
--*     unless otherwise stated below.                         *
--*                                                            *
--*     In case of problems/questions/bug reports etc. please  *
--*     contact michael.niegl@cern.ch                          *
--*                                                            *
--**************************************************************

--**************************************************************
--*                                                            *
--*  $Source: /local/reps/bcmfpga/bcm_aaa/bcm_aaa/lcd/univibrator.vhd,v $
--*  $Revision: 1.4.2.3 $                                          *
--*  $Name: dev $                                                 *
--*  $Author: mniegl $                                         *
--*  $Date: 2008/11/03 17:57:46 $                              *


--*                                                            *
--**************************************************************

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;


entity univibrator is
  port (CLOCK      : in  std_logic;
        TRIGER     : in  std_logic;
        SIGNAL_OUT : out std_logic := '0'
        );
end univibrator;


architecture univibrator_arc of univibrator is

  signal int_operate : std_logic                     := '0';
  signal int_latch   : std_logic                     := '0';
  signal int_count   : std_logic_vector (2 downto 0) := "000";

begin


  rising_clock : process (CLOCK) is     --positive edges
  begin
    if (CLOCK'event and CLOCK = '1') then       --rising edge
      if int_latch = '0' and TRIGER = '1' then  --rising edge of TRIGGER detected
        int_operate <= '1';
        SIGNAL_OUT  <= '1';
        int_count   <= "000";
      end if;
      if int_operate = '1' then
        int_count <= int_count + 1;
        if int_count = "011" then       --end of signal
          int_operate <= '0';
          SIGNAL_OUT  <= '0';
        end if;
      end if;
      int_latch <= TRIGER;
    end if;
  end process;
  
end univibrator_arc;

---

Author: M.Niegl

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