clock.vhd

该程序实现一个数字钟

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity clock is
 port(clk:in std_logic;
      clr:in std_logic;
      en:in std_logic;
      mode:in std_logic;
      inc:in std_logic;
      seg7:out std_logic_vector(6 downto 0);
      scan:out std_logic_vector(5 downto 0) 
     );
end clock;

architecture one of clock is
signal state:std_logic_vector(1 downto 0);
signal qhh,qhl,qmh,qml,qsh,qsl:std_logic_vector(3 downto 0);
signal data:std_logic_vector(3 downto 0);
signal cnt:integer range 0 to 5;
signal clk1khz,clk1hz,clk2hz:std_logic;
signal blink:std_logic_vector(2 downto 0);
signal inc_reg:std_logic;
signal sec,min:integer range 0 to 59;
signal hour:integer range 0 to 23;
begin

process(clk)
variable count:integer range 0 to 24999;
begin
 if clk'event and clk='1' then
   if count=24999 then
      clk1khz<=not clk1khz;
      count:=0;
   else 
      count:=count+1;
   end if;
 end if;
end process;

process(clk1khz)
variable count:integer range 0 to 499;
begin
 if clk1khz'event and clk1khz='1'then
   if count=499 then
     clk1hz<=not clk1hz;
     count:=0;
   else
     count:=count+1;
   end if;
end if;
end process;

process(clk1khz)
variable count:integer range 0 to 249;
begin
 if clk1khz'event and clk1khz='1'then
   if count=249 then
     clk2hz<=not clk2hz;
     count:=0;
   else
     count:=count+1;
   end if;
end if;
end process;

process(mode,clr)
 begin
 if clr='1'then
  state<="00";
 elsif mode'event and mode='0'then
   state<=state+1;
 end if;
end process;

process(clk1hz,state,en,clr,hour,sec,min)
begin
 if en='1'then
   hour<=hour;
   min<=min;
   sec<=sec;
 elsif clr='1'then
   hour<=0;
   min<=0;
   sec<=0;
 elsif clk1hz'event and clk1hz='1'then
  case state is
  when"00"=>if sec=59 then sec<=0;
             if min=59 then min<=0;
              if hour=23 then hour<=0;
              else hour<=hour+1;end if;
             else min<=min+1;end if;
            else sec<=sec+1;
            end if;
  when"01"=>if inc='1'then
             if inc_reg='0'then inc_reg<='1';
              if hour=23 then
                   hour<=0;
              else hour<=hour+1;
              end if;
             end if;
            else inc_reg<='0';
            end if;
  when"10"=>if inc='1'then
             if inc_reg='0'then inc_reg<='1';
              if min=59 then
                   min<=0;
              else min<=min+1;
              end if;
             end if;
            else inc_reg<='0';
            end if;
 when"11"=>if inc='1'then
             if inc_reg='0'then inc_reg<='1';
              if sec=59 then
                   sec<=0;
              else sec<=sec+1;
              end if;
             end if;
            else inc_reg<='0';
            end if;
 end case;
end if;
end process;

process(state,clk2hz)
 begin
  case state is
    when"00"=>blink<="000";
    when"01"=>blink<=(2=>clk2hz,others=>'0');
    when"10"=>blink<=(1=>clk2hz,others=>'0');
    when"11"=>blink<=(0=>clk2hz,others=>'0');
  end case;
end process;

process(sec)
 begin
  case sec is
   when 0|10|20|30|40|50=>qsl<="0000";
   when 1|11|21|31|41|51=>qsl<="0001";
   when 2|12|22|32|42|52=>qsl<="0010";
   when 3|13|23|33|43|53=>qsl<="0011";
   when 4|14|24|34|44|54=>qsl<="0100";
   when 5|15|25|35|45|55=>qsl<="0101";
   when 6|16|26|36|46|56=>qsl<="0110";
   when 7|17|27|37|47|57=>qsl<="0111";
   when 8|18|28|38|48|58=>qsl<="1000";
   when 9|19|29|39|49|59=>qsl<="1001";
   when others=>null;
  end case;
  case sec is
   when 0|1|2|3|4|5|6|7|8|9=>qsh<="0000";
   when 10|11|12|13|14|15|16|17|18|19=>qsh<="0001";
   when 20|21|22|23|24|25|26|27|28|29=>qsh<="0010";
   when 30|31|32|33|34|35|36|37|38|39=>qsh<="0011";
   when 40|41|42|43|44|45|46|47|48|49=>qsh<="0100";
   when 50|51|52|53|54|55|56|57|58|59=>qsh<="0101";
  end case;
 end process;

process(min)
 begin
  case min is
   when 0|10|20|30|40|50=>qml<="0000";
   when 1|11|21|31|41|51=>qml<="0001";
   when 2|12|22|32|42|52=>qml<="0010";
   when 3|13|23|33|43|53=>qml<="0011";
   when 4|14|24|34|44|54=>qml<="0100";
   when 5|15|25|35|45|55=>qml<="0101";
   when 6|16|26|36|46|56=>qml<="0110";
   when 7|17|27|37|47|57=>qml<="0111";
   when 8|18|28|38|48|58=>qml<="1000";
   when 9|19|29|39|49|59=>qml<="1001";
   when others=>null;
  end case;
  case min is
   when 0|1|2|3|4|5|6|7|8|9=>qmh<="0000";
   when 10|11|12|13|14|15|16|17|18|19=>qmh<="0001";
   when 20|21|22|23|24|25|26|27|28|29=>qmh<="0010";
   when 30|31|32|33|34|35|36|37|38|39=>qmh<="0011";
   when 40|41|42|43|44|45|46|47|48|49=>qmh<="0100";
   when 50|51|52|53|54|55|56|57|58|59=>qmh<="0101";
  end case;
 end process;

process(hour)
 begin
  case hour is
   when 0|10|20=>qhl<="0000";
   when 1|11|21=>qhl<="0001";
   when 2|12|22=>qhl<="0010";
   when 3|13|23=>qhl<="0011";
   when 4|14=>qhl<="0100";
   when 5|15=>qhl<="0101";
   when 6|16=>qhl<="0110";
   when 7|17=>qhl<="0111";
   when 8|18=>qhl<="1000";
   when 9|19=>qhl<="1001";
   when others=>null;
  end case;
 case hour is
   when 0|1|2|3|4|5|6|7|8|9=>qhh<="0000";
   when 10|11|12|13|14|15|16|17|18|19=>qhh<="0001";
   when 20|21|22|23=>qhh<="0010";
   when others=>null;
 end case;
end process;

process (clk1khz)
 begin
  if clk1khz'event and clk1khz='1' then
    if cnt=5 then cnt<=0;
    else cnt<=cnt+1;
    end if;
  end if;
end process;

process(cnt,qhh,qhl,qmh,qml,qsh,qsl,blink)
 begin
 case cnt is
  when 0=>data<=qsl or (blink(0)&blink(0)&blink(0)&blink(0));scan<="111110";
  when 1=>data<=qsh or (blink(0)&blink(0)&blink(0)&blink(0));scan<="111101";
  when 2=>data<=qml or (blink(1)&blink(1)&blink(1)&blink(1));scan<="111011";
  when 3=>data<=qmh or (blink(1)&blink(1)&blink(1)&blink(1));scan<="110111";
  when 4=>data<=qhl or (blink(2)&blink(2)&blink(2)&blink(2));scan<="101111";
  when 5=>data<=qhh or (blink(2)&blink(2)&blink(2)&blink(2));scan<="011111";
  when others=>null;
 end case;
end process;

process(data)
 begin
  case data is
   WHEN"0000"=>seg7<="1000000";
   WHEN"0001"=>seg7<="1111001";
   WHEN"0010"=>seg7<="0100100";
   WHEN"0011"=>seg7<="0110000";
   WHEN"0100"=>seg7<="0011001";
   WHEN"0101"=>seg7<="0010010";
   WHEN"0110"=>seg7<="0000010";
   WHEN"0111"=>seg7<="1111000";
   WHEN"1000"=>seg7<="0000000";
   WHEN"1001"=>seg7<="0010000";
   WHEN others=>seg7<="0000000";
 end case;
end process;
end one;