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[/] [System09/] [trunk/] [rtl/] [VHDL/] [SevenSegment.vhd] - Rev 122
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--===========================================================================-- -- -- -- SevenSegment.vhd - Synthesizable Multiplex Seven Segment LED Driver -- -- -- --===========================================================================-- -- -- File name : SevenSegment.vhd -- -- Entity name : SevenSegment -- -- Purpose : 4 x 8 bit lathes to display 7 segments -- Multiplexes segment registers across 4 displays. -- For use on the Digilent Spartan 3 Starter Board -- -- Dependencies : ieee.std_logic_1164 -- ieee.std_logic_unsigned -- unisim.vcomponents -- -- Author : John E. Kent -- -- Email : dilbert57@opencores.org -- -- Web : http://opencores.org/project,system09 -- -- SevenSegment.vhd is a multiplexed seven segment LED display driver written in VHDL -- -- Copyright (C) 2004 - 2010 John Kent -- -- This program is free software: you can redistribute it and/or modify -- it under the terms of the GNU General Public License as published by -- the Free Software Foundation, either version 3 of the License, or -- (at your option) any later version. -- -- This program 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 General Public License for more details. -- -- You should have received a copy of the GNU General Public License -- along with this program. If not, see <http://www.gnu.org/licenses/>. -- --===========================================================================-- -- -- -- Revision History -- -- -- --===========================================================================-- -- -- Version Author Date Description -- 0.1 John Kent 19 Oct 2004 Initial version -- 0.2 John Kent 21 Nov 2006 Inverted segment registers -- so '0' in segment registers -- switches segment OFF -- 0.3 John Kent 31 May 2010 Updated Header and GPL. -- library ieee; use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; library unisim; use unisim.vcomponents.all; entity seven_segment is port ( clk : in std_logic; rst : in std_logic; cs : in std_logic; rw : in std_logic; addr : in std_logic_vector(1 downto 0); data_in : in std_logic_vector(7 downto 0); data_out : out std_logic_vector(7 downto 0); segments : out std_logic_vector(7 downto 0); digits : out std_logic_vector(3 downto 0) ); end; architecture rtl of seven_segment is signal seg_reg0 : std_logic_vector(7 downto 0); signal seg_reg1 : std_logic_vector(7 downto 0); signal seg_reg2 : std_logic_vector(7 downto 0); signal seg_reg3 : std_logic_vector(7 downto 0); signal ClockDivider : std_logic_vector(13 downto 0); signal WhichDigit : std_logic_vector(1 downto 0); begin --------------------------------- -- -- Write Segment registers -- --------------------------------- seg_write : process( clk, rst, addr, cs, rw, data_in ) begin if clk'event and clk = '0' then if rst = '1' then seg_reg0 <= "00000000"; seg_reg1 <= "00000000"; seg_reg2 <= "00000000"; seg_reg3 <= "00000000"; else if cs = '1' and rw = '0' then case addr is when "00" => seg_reg0 <= data_in; when "01" => seg_reg1 <= data_in; when "10" => seg_reg2 <= data_in; when "11" => seg_reg3 <= data_in; when others => null; end case; end if; end if; end if; end process; --------------------------------- -- -- Read Segment registers -- --------------------------------- seg_read : process( addr, seg_reg0, seg_reg1, seg_reg2, seg_reg3 ) begin case addr is when "00" => data_out <= seg_reg0; when "01" => data_out <= seg_reg1; when "10" => data_out <= seg_reg2; when "11" => data_out <= seg_reg3; when others => null; end case; end process; --------------------------------- -- -- Output Segment registers -- --------------------------------- seg_out : process( rst, Clk) begin if rst = '1' then ClockDivider <= (others => '0'); WhichDigit <= "00"; Segments <= "00000000"; Digits <= "1111"; elsif Clk'Event and Clk = '0' then if ClockDivider = "11000011010011" then ClockDivider <= (others => '0'); case WhichDigit is -- note that everything is pipelined when "00" => Digits <= "1110"; Segments <= not( seg_reg0 ); when "01" => Digits <= "1101"; Segments <= not( seg_reg1 ); when "10" => Digits <= "1011"; Segments <= not( seg_reg2 ); when "11" => Digits <= "0111"; Segments <= not( seg_reg3 ); when others => null; end case; WhichDigit <= WhichDigit + 1; else ClockDivider <= ClockDivider + 1; end if; end if; end process; end rtl;
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