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--

-- UART Baudrate generator

--

-- Author:   Sebastian Witt

-- Date:     27.01.2008

-- Version:  1.1

--

-- This code is free software; you can redistribute it and/or

-- modify it under the terms of the GNU Lesser General Public

-- License as published by the Free Software Foundation; either

-- version 2.1 of the License, or (at your option) any later version.

--

-- This code is distributed in the hope that it will be useful,

-- but WITHOUT ANY WARRANTY; without even the implied warranty of

-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

-- Lesser General Public License for more details.

--

-- You should have received a copy of the GNU Lesser General Public

-- License along with this library; if not, write to the

-- Free Software  Foundation, Inc., 59 Temple Place, Suite 330,

-- Boston, MA  02111-1307  USA

--

LIBRARY IEEE;

USE IEEE.std_logic_1164.all;

USE IEEE.numeric_std.all;

-- Serial UART baudrate generator

entity uart_baudgen is

    port (

        CLK         : in std_logic;                                 -- Clock

        RST         : in std_logic;                                 -- Reset

        CE          : in std_logic;                                 -- Clock enable

        CLEAR       : in std_logic;                                 -- Reset generator (synchronization)

        DIVIDER     : in std_logic_vector(15 downto 0);             -- Clock divider

        BAUDTICK    : out std_logic                                 -- 16xBaudrate tick

    );

end uart_baudgen;

architecture rtl of uart_baudgen is

    -- Signals

    signal iCounter : unsigned(15 downto 0);

begin

    -- Baudrate counter

    BG_COUNT: process (CLK, RST)

    begin

        if (RST = '1') then

            iCounter <= (others => '0');

            BAUDTICK <= '0';

        elsif (CLK'event and CLK = '1') then

            if (CLEAR = '1') then

                iCounter <= (others => '0');

            elsif (CE = '1') then

                iCounter <= iCounter + 1;

            end if;

            BAUDTICK <= '0';

            if (iCounter = unsigned(DIVIDER)) then

                iCounter <= (others => '0');

                BAUDTICK <= '1';

            end if;

        end if;

    end process;

end rtl;