PS2.vhd

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity PS2 is port(     PS2C: in STD_LOGIC;
                        PS2D: in STD_LOGIC;
                        AN : out STD_LOGIC_VECTOR (3 DOWNTO 0);
                        LED : out STD_LOGIC_VECTOR (7 DOWNTO 0);
                        SEG : out STD_LOGIC_VECTOR (6 DOWNTO 0));
end PS2;

architecture BEHAVIORAL of PS2 is
    begin
    MAIN: process(PS2C)
    variable State : STD_LOGIC_VECTOR(3 DOWNTO 0) := "0000";
    variable Data : STD_LOGIC_VECTOR(7 DOWNTO 0) := "00000000";
    begin
        AN(3 DOWNTO 0) <= "1110";
        if falling_edge(PS2C) then
            if State = "0000" then
                if PS2D = '0' then --start
                    State := State + 1;
                    Data(7 DOWNTO 0) := "00000000";
                end if;
            elsif State = "0001" then --D0
                Data(0) := PS2D;
                State := State + 1;
            elsif State = "0010" then --D1
                Data(1) := PS2D;
                State := State + 1;
            elsif State = "0011" then --D2
                Data(2) := PS2D;
                State := State + 1;
            elsif State = "0100" then --D3
                Data(3) := PS2D;
                State := State + 1;
            elsif State = "0101" then --D4
                Data(4) := PS2D;
                State := State + 1;
            elsif State = "0110" then --D5
                Data(5) := PS2D;
                State := State + 1;
            elsif State = "0111" then --D6
                Data(6) := PS2D;
                State := State + 1;
            elsif State = "1000" then --D7
                Data(7) := PS2D;
                State := State + 1;
            elsif State = "1001" then --Parity
                State := State + 1;
            elsif State = "1010" then --stop
                State := "0000";
            end if;
            case Data is
                when "00011100" =>  SEG(6 DOWNTO 0) <= "0000010";     --A
                when "00110010" =>  SEG(6 DOWNTO 0) <= "0000100";     --B
                when "00100001" =>  SEG(6 DOWNTO 0) <= "0110001";     --C
                when "00100011" =>  SEG(6 DOWNTO 0) <= "1000010";     --D
                when "00100100" =>  SEG(6 DOWNTO 0) <= "0110000";     --E
                when "00101011" =>  SEG(6 DOWNTO 0) <= "0111000";     --F
                when "01000101" =>  SEG(6 DOWNTO 0) <= "0000001";     --0
                when "00010110" =>  SEG(6 DOWNTO 0) <= "1001111";   --1
                when "00011110" =>  SEG(6 DOWNTO 0) <= "0010010";     --2
                when "00100110" =>  SEG(6 DOWNTO 0) <= "0000110";     --3
                when "00100101" =>  SEG(6 DOWNTO 0) <= "1001100";     --4
                when "00101110" =>  SEG(6 DOWNTO 0) <= "0100100";     --5
                when "00110110" =>  SEG(6 DOWNTO 0) <= "0100000";   --6
                when "00111101" =>  SEG(6 DOWNTO 0) <= "0001111";   --7
                when "00111110" =>  SEG(6 DOWNTO 0) <= "0000000";   --8
                when "01000110" =>  SEG(6 DOWNTO 0) <= "0000100";   --9
                when others =>      SEG(6 DOWNTO 0) <= "1111111";   -- any other key
            end case;
            LED(7 DOWNTO 0) <= Data;
        end if;
    end process;
end BEHAVIORAL;