VHDL 3位7段显示

Question

我遇到来自http://langster1980.blogspot.com/2015/09/more-on-seven-segment-displays-and.html

的代码段问题

我的代码：

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.numeric_std.all;

entity main is
port ( 
    clock_in : in std_logic;
    Seven_Segment_Enable : out std_logic_vector(2 downto 0);
    Seven_Segment_Display : out std_logic_vector(7 downto 0) 
         );
end main;

architecture Behavioral of main is

signal refresh_count : integer := 0;
signal refresh_clk : std_logic := '1';

signal second_count : integer := 0;
signal second_clk : std_logic := '1';

signal digit_sel : unsigned(1 downto 0);
signal bcd : integer := 0;
signal Seven_Segment_Display_output : std_logic_vector (7 downto 0) := (others => '0');
signal bcd0, bcd1, bcd2 : integer := 0;

signal unit_count : integer := 0;
signal ten_count : integer := 0;
signal hundred_count : integer := 0;

begin

process(Clock_in)

begin

if(clock_in'event and clock_in='1') then 
refresh_count <= refresh_count+1;
second_count <= second_count+1;

if(second_count = 750000) then
second_clk <= not second_clk;
second_count <= 1;
end if;

if(refresh_count = 1200) then
refresh_clk <= not refresh_clk;
refresh_count <= 1;
end if;

end if;

end process; 

process(second_clk)

begin

if(second_clk'event and second_clk='1') then
  bcd0 <= 0;
  bcd1 <= 1;
  bcd2 <= 2;

end if;

end process;

process(refresh_clk)

begin

if(refresh_clk' event and refresh_clk='1') then
digit_sel <= digit_sel + 1;

end if;  

end process;

with digit_sel select
    bcd <= bcd0 when "00",
           bcd1 when "01",
           bcd2 when others;

with digit_sel select
    Seven_Segment_Enable <= "110" when "00",
                            "101" when "01",
                            "011" when others;
with bcd select

Seven_Segment_Display_output(7 downto 0) <= B"00000011" when 0,
     B"11110011" when 1,
     B"00100101" when 2,
     B"01100001" when 3,
     B"11010001" when 4,
     B"01001001" when 5,
     B"00001001" when 6,
     B"11100011" when 7,
     B"00000001" when 8,
     B"01000001" when 9,
     B"11111111" when others;

Seven_Segment_Display(7 downto 0) <= Seven_Segment_Display_output(7 downto 0);  

end Behavioral; 

我的问题是在显示屏上画画。 根据代码应绘制数字012，但我的结果是

（点击放大）

我不知道如何解决它。 你不知道该怎么办吗？

抱歉我的英语不好。