cntm9999.vhd

一个至少4位的十进制计数器

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_arith.all;
entity cntm9999 is
port(dout:out std_logic_vector(6 downto 0);
     scan: out std_logic_vector(1 downto 0);
     clk:in std_logic;
     load:in std_logic;
     en: in std_logic;
     updn: in std_logic;
     co:out std_logic;
     d1:in std_logic_vector(3 downto 0);
     d2:in std_logic_vector(3 downto 0);
     d3:in std_logic_vector(3 downto 0);
     d4:in std_logic_vector(3 downto 0));
end;

architecture art of cntm9999 is
  signal co1: std_logic;
  signal co2: std_logic;
  signal co3: std_logic;
  signal data:std_logic_vector(3 downto 0);
  signal cnt4:std_logic_vector(1 downto 0);
  signal q1:std_logic_vector(3 downto 0);
  signal q2:std_logic_vector(3 downto 0);
  signal q3:std_logic_vector(3 downto 0);
  signal q4:std_logic_vector(3 downto 0);
  signal CLK10_1 : std_logic;
begin
------------------------------------------20分频
PROCESS(CLK)
VARIABLE COUNT:INTEGER RANGE 0 TO 9;
BEGIN
IF CLK'EVENT AND CLK='1' THEN
  IF COUNT=9 THEN
    CLK10_1<=NOT CLK10_1;
    COUNT:=0;
  ELSE
    COUNT:=COUNT+1;
  END IF;
END IF;
END PROCESS;
------------------9999进制加减计数器
------------------个位
process(CLK10_1,load)
begin
if load='1' then q1<=d1;
elsif rising_edge(CLK10_1) then
     if en='1' then
       if updn='1' then
           if q1="1001" then
              q1<="0000";co1<='1';
           else
              q1<=q1+1;co1<='0';
           end if;
        elsif updn='0' then
           if q1="0000" then
              q1<="1001";co1<='1';
           else
              q1<=q1-1;co1<='0';
           end if;
        end if;
     end if;
end if;
end process;
------------------十位
PROCESS(co1,load)
BEGIN
IF load='1' THEN
  Q2<=D2;
ELSIF (CO1'EVENT AND CO1='1') THEN
    if en='1' then
      IF UPDN='1' THEN
        IF Q2="1001" THEN
           Q2<="0000";CO2<='1';
        ELSE 
          Q2<=Q2+1;CO2<='0';
        END IF;
      ELSIF UPDN='0' THEN
        IF Q2="0000" THEN
          Q2<="1001";CO2<='1';
        ELSE 
          Q2<=Q2-1;CO2<='0';
        END IF;
      END IF;
    end if;
END IF;
END PROCESS;
------------------百位
process(co2,load)
begin
if load='1' then q3<=d3;   
elsif rising_edge(co2)  then
     if en='1' then
       if updn='1' then
           if q3="1001" then
              q3<="0000";co3<='1';
           else
              q3<=q3+1;co3<='0';
           end if;
        elsif updn='0' then
           if q3="0000" then
              q3<="1001";co3<='1';
           else
              q3<=q3-1;co3<='0';
           end if;
        end if;
     end if;
   end if;
end process;
------------------
process(co3,load)
begin
if load='1' then q4<=d4;
elsif  rising_edge(co3)  then
    if en='1' then
       if updn='1' then
           if q4="1001" then
              q4<="0000";co<='1';
           else
              q4<=q4+1;co<='0';
           end if;
        elsif updn='0' then
           if q4="0000" then
              q4<="1001";co<='1';
           else
              q4<=q4-1;co<='0';
           end if;
        end if;
   end if;
end if;
end process;

------------------4进制计数器
process(clk)
begin
if (clk'event and clk='1') then
   if (cnt4="11") then  
        cnt4<="00";
   else
         cnt4<=cnt4+'1';
   end if;
end if;
end process;
------------------数码管地址扫描
process(cnt4)
begin
case cnt4 is
when "00"=>scan<="00";data<=q1;
when "01"=>scan<="01";data<=q2;
when "10"=>scan<="10";data<=q3;
when "11"=>scan<="11";data<=q4;
when others=>null;
end case;
end process;
------------------8段译码
process(data)
begin
case data is    
   when "0000"=>dout<="0111111";            ----显示0 
   when "0001"=>dout<="0000110";            ----显示1
   when "0010"=>dout<="1011011";            ----显示2
   when "0011"=>dout<="1001111";            ----显示3
   when "0100"=>dout<="1100110";            ----显示4
   when "0101"=>dout<="1101101";            ----显示5
   when "0110"=>dout<="1111101";            ----显示6
   when "0111"=>dout<="0000111";            ----显示7
   when "1000"=>dout<="1111111";            ----显示8
   when "1001"=>dout<="1101111";            ----显示9
   when others=>null;
end case;
end process;
end;