counter24.vhd

这是一个实现时分秒的时钟功能的源码

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

entity counter24 is
    port(clk:in std_logic;
         reset:in std_logic;
         din:in std_logic_vector(5 downto 0);
         dout:out std_logic_vector(5 downto 0));
end counter24;

architecture Behavioral of counter24 is
    signal count:std_logic_vector(5 downto 0);
begin
    dout<=count;
process(clk,reset,din)
begin
     if reset='0' then
         count<=din;
         
     elsif rising_edge(clk) then
         if count(3 downto 0)="1001" then
             count(3 downto 0)<="0000";
             count(5 downto 4)<=count(5 downto 4)+1;
         else
             count(3 downto 0)<=count(3 downto 0)+1;
         end if;
         if count="100011" then
              count<="000000";  
         end if;
       end if;
end process;
end Behavioral;