clock.vhd

基于fpga数字钟系统

library ieee;
use ieee.std_logic_1164.all; 
use ieee.std_logic_unsigned.all;
entity clock is
  port(clk,set,s1,s2,s3:in std_logic;
       second1,second2,minite1,minite2,hour1,hour2:out std_logic_vector(3 downto 0);
      cout:out std_logic);
end entity;
architecture one of clock is
begin 
  process(clk,set,s1,s2,s3)
 variable msecond1,msecond2,mminite1,mminite2,mhour11,mhour22:std_logic_vector(3 downto 0);
 begin 
    if clk'event and clk='1' then
       
       if set='0' then      -----启动校验
         --if s1='0'  
          --then msecond1:=msecond1+1;
           --if msecond1="1010"
             -- then msecond1:="0000";
                 --msecond2:=msecond2+1;
                  -- if msecond2="0110" then msecond2:="0000";
                  --end if;
           --end if;
          --end if;    --------秒校验
         if s2='0' then 
                mminite1:=mminite1+1;
                     if mminite1="1010"
                        then mminite1:="0000";
                             mminite2:=mminite2+1;
                            if mminite2="0110" 
                               then mminite2:="0000";
                            end if;
                     end if;
                  end if;     ---------分校验
       if s3='0' then 
               mhour11:=mhour11+1;
                    if mhour11="1010" then
                          mhour11:="0000";
                              if mhour22<"0010" then
                                      mhour22:=mhour22+1;
                              end if;
                    elsif mhour22="0010" and mhour11="0100" then
                                 mhour22:="0000";
                                 mhour11:="0000";
                                  
                    end if;
                                   
     
         end if;-------时校验
        elsif s1='0' then
            msecond1:="0000"; msecond2:="0000";
            mminite1:="0000"; mminite2:="0000";
            mhour11:="0000";  mhour22:="0000";
            
      else  msecond1:=msecond1+1;-----正常计时工作
      if msecond1="1010"
        then msecond1:="0000";
             msecond2:=msecond2+1;
            if msecond2="0110"
                 then msecond2:="0000";
                       cout<='1';--f
                      mminite1:=mminite1+1;
                     if mminite1="1010"
                        then mminite1:="0000";
                             mminite2:=mminite2+1;
                            if mminite2="0110" 
                               then mminite2:="0000";
                                    mhour11:=mhour11+1;
                                       if mhour11="1010" then
                                              mhour11:="0000";
                                             if mhour22<"0010" then
                                                mhour22:=mhour22+1;
                                               end if;
                                        elsif mhour22="0010" and mhour11="0100" then
                                           mhour22:="0000";
                                              mhour11:="0000";
                                  
                                         end if;
                                   
                                                                                                  
end if;                                   
end if;
end if;
end if;
            
end if;
end if;
second1<=msecond1;
second2<=msecond2;
minite1<=mminite1;
minite2<=mminite2;
hour1<=mhour11;
hour2<=mhour22;
end process;
--process(s1)
--begin
--if si='0' then
    
end architecture one;