project3.vhd

用VHDL语言实现一个10秒倒计时电路

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;

entity project3 is
port(ctrl:in std_logic;
     row,col:out std_logic_vector(7 downto 0);
     clk:in std_logic;
     alarm:out std_logic);
end;

architecture behave of project3 is
constant U1:integer:=49999;               
constant U2:integer:=24999999;           
signal col0,col1,col2,col3,col4,col5,col6,col7: std_logic_vector(7 downto 0);
signal count:std_logic_vector( 3 downto 0);
signal clk1,clk2:std_logic;
signal ctrl_c: integer range 0 to 2;
signal cou1:std_logic;
begin

process(clk)                
variable count1:integer range 0 to U1;
variable count2:integer range 0 to U2; 
begin
 if(clk'event and clk='0') then
   if(count1=U1) then
     clk1<=not clk1;
     count1:=0;
   else 
     count1:=count1+1;
   end if;
   if(count2=U2) then
     clk2<=not clk2;
     count2:=0;
   else
     count2:=count2+1;
   end if;
 end if;
end process;

process(clk1,ctrl)
 variable cou: integer range 0 to 4;   
  begin
  if(ctrl='1')  then
    if(clk1'event and clk1='0') then
       if(cou=4) then
         cou1<='1';
       else
         cou:=cou+1;
       end if;
      end if;
  else
    cou:=0; 
    cou1<='0';
  end if;
  if( cou1'event and cou1='1' ) then
    if(ctrl_c=2)  then   
      ctrl_c<=0;
    else
      ctrl_c<=ctrl_c+1;
    end if;
  end if;
end process;



process(clk2,ctrl_c)                
begin 
  if(ctrl_c=0)  then   
    if(count="1010")  then
      count<="0000";
    end if;
  elsif (ctrl_c=1) then
       if(clk2'event and clk2='0') then
         if(count="1001") then
           alarm<='1';
         else 
           count<=count+1;
           alarm<='0';
           col7<="00000000";
         end if;
       end if;
  elsif(ctrl_c=2) then
        alarm<='0';
        count<="1010";
  end if;
    case count is                   
      when "0000"=>   --9
        col0<="00000000";
        col1<="01110010";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01111110"; 
        col7<="00000000";
      when "0001"=>  --8
        col0<="00000000";
        col1<="01111110";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01111110"; 
        col7<="00000000";
      when "0010"=> --7
        col0<="00000000";
        col1<="01000000";
        col2<="01000000";
        col3<="01000000";
        col4<="01000000";
        col5<="01000000";
        col6<="01111110";
        col7<="00000000";
      when "0011"=> --6
        col0<="00000000";
        col1<="01111110";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01011110";
        col7<="00000000";
      when "0100"=>  --5
        col0<="00000000";
        col1<="01110010";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01011110";
        col7<="00000000";
      when "0101"=>  --4
        col0<="00000000";
        col1<="01110000";
        col2<="00010000";
        col3<="00010000";
        col4<="01111110";
        col5<="00010000";
        col6<="00010000";
        col7<="00000000";
      when "0110"=> --3
        col0<="00000000";
        col1<="01010010";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01111110";
        col7<="00000000";
      when "0111"=> --2
        col0<="00000000";
        col1<="01011110";
        col2<="01010010";
        col3<="01010010";
        col4<="01010010";
        col5<="01010010";
        col6<="01110010";
        col7<="00000000"; 
      when "1000"=> --1
        col0<="00000000";
        col1<="00000000";
        col2<="00000000";
        col3<="01111110";
        col4<="00000000";
        col5<="00000000";
        col6<="00000000";
        col7<="00000000"; 
      when "1001"=>  --0
        col0<="00000000";
        col1<="01111110";
        col2<="01000010";
        col3<="01000010";
        col4<="01000010";
        col5<="01000010";
        col6<="01111110";
        col7<="00000001"; 
    when others=>    --0'
        col0<="00000000";
        col1<="01111110";
        col2<="01000010";
        col3<="01000010";
        col4<="01000010";
        col5<="01000010";
        col6<="01111110";
        col7<="00000000"; 
       
      end case ;

end process;


process(clk1,count)                           
 variable count3:integer range 0 to 7;
 begin 
 if(clk1'event and clk1='0') then
   case count3 is
     when 0=>
       row<=col0;
       col<="01111111";
     when 1=>
       row<=col1;
       col<="10111111";
     when 2=>
       row<=col2;
       col<="11011111";
     when 3=>
       row<=col3;
       col<="11101111";
     when 4=>
       row<=col4;
       col<="11110111";
     when 5=>
       row<=col5;
       col<="11111011";
     when 6=>
       row<=col6;
       col<="11111101";
     when 7=>
       row<=col7;
       col<="11111110";
     end case;
   count3:=count3+1;
 end if;
end process;
end ;