dec_7seg.vhd

library IEEE use IEEE.STD_LOGIC_1164.all use IEEE.STD_LOGIC_ARITH.all use IEEE.STD_LOGIC_UNSIG

library IEEE;
use  IEEE.STD_LOGIC_1164.all;
use  IEEE.STD_LOGIC_ARITH.all;
use  IEEE.STD_LOGIC_UNSIGNED.all;

ENTITY dec_7seg IS
	PORT(hex_digit		: IN	STD_LOGIC_VECTOR(3 downto 0);
		 segment_a, segment_b, segment_c, segment_d, segment_e, 
		 segment_f, segment_g : out std_logic);
END dec_7seg;

ARCHITECTURE a OF dec_7seg IS
	SIGNAL segment_data : STD_LOGIC_VECTOR(6 DOWNTO 0);
BEGIN
PROCESS  (Hex_digit)
-- HEX to 7 Segment Decoder for LED Display
BEGIN
CASE Hex_digit IS
        WHEN "0000" =>
            segment_data <= "1111110";
        WHEN "0001" =>
            segment_data <= "0110000";
        WHEN "0010" =>
            segment_data <= "1101101";
        WHEN "0011" =>
            segment_data <= "1111001";
        WHEN "0100" =>
            segment_data <= "0110011";
        WHEN "0101" =>
            segment_data <= "1011011";
        WHEN "0110" =>
            segment_data <= "1011111";
        WHEN "0111" =>
            segment_data <= "1110000";
        WHEN "1000" =>
            segment_data <= "1111111";
        WHEN "1001" =>
            segment_data <= "1111011"; 
        WHEN "1010" =>
            segment_data <= "1110111";
        WHEN "1011" =>
            segment_data <= "0011111"; 
        WHEN "1100" =>
            segment_data <= "1001110"; 
        WHEN "1101" =>
            segment_data <= "0111101"; 
        WHEN "1110" =>
            segment_data <= "1001111"; 
        WHEN "1111" =>
            segment_data <= "1000111"; 
	   WHEN OTHERS =>
            segment_data <= "0111110";
END CASE;
END PROCESS;

-- extract segment data and LED driver is inverted
segment_a <= NOT segment_data(6);
segment_b <= NOT segment_data(5);
segment_c <= NOT segment_data(4);
segment_d <= NOT segment_data(3);
segment_e <= NOT segment_data(2);
segment_f <= NOT segment_data(1);
segment_g <= NOT segment_data(0);

END a;