一、  紀年的程序：
       閏年2月為29天，平年為28天。閏年的確定是年份的低兩位能被四整除為閏年（00年除外）當低兩位為00時，高兩位為400的整數倍為閏年，否則為平年。關于這個知識點具體請看：http://www.izizhuan.cn/mcu/2248.html
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity year is
  port(m,cr:in std_logic;
       mouth:in std_logic_vector(3 downto 0);
       s1,s0 ,runout:out std_logic;    
       YH1,YH0,YL1,YL0:out std_logic_vector(3 downto 0));
end year;
architecture mm of year is
 signal y11,y12,y01,y02:std_logic_vector(3 downto 0);
 signal data1,data0 :std_logic_vector(6 downto 0);
 signal run0,run1:std_logic_vector(2 downto 0);
 signal c0,c1,c2,c3,r1,r0,r:std_logic;
   begin
    process(m,cr) 
      begin
      --年低兩位      
         if m'event and m='1' then
                if y01=9 then y01<="0000";c0<='1';
                 else y01<=y01+1;c0<='0';
                end if;
                if data0=99 then data0<="0000000";
                 else data0<=data0+1;
                end if;
                if run0=3 then run0<="000";r0<='1';
                 else run0<=run0+1;r0<='0';
                end if;             
          end if;
          if c0'event and c0='1' then
                if y02=9 then y02<="0000";c1<='1';
                  else y02<=y02+1;c1<='0';
                end if;
           end if;
   --年高兩位。
         if c1'event and c1='1' then
               if data1=99 then data1<="0000000";
                  else data1<=data1+1;
               end if;
               if run1=3 then run1<="000";
                   else run1<=run1+1;
               end if;             
               if y11=9 then y11<="0000";c2<='1';
                  else y11<=y11+1;c2<='0';
               end if;
           end if;
           if c2'event and c2='1' then
                if y12=9 then y12<="0000";
                 else y12<=y12+1;
                end if;         
           end if;
           if run1/=0 and data0=0  then r1<='0';
                   else r1<='1';
           end if;
           r<=r0 and r1;
           if mouth=2  then
                 if r='1' then s1<='1';s0<='1';
                    else s1<='1'; s0<='0';
                  end if;
              elsif mouth=4 or mouth=6 or mouth=9 or mouth=11 then s1<='0';s0<='1';
              else s1<='0';s0<='0';
            end if;             
   end process; 
  YH1<=y12;YH0<=y11;YL1<=y02;YL0<=y01;runout<=r;
end; 
二、月份的程序，公歷。
 library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity mouth is
 port(day,cr,tm:in std_logic;
      m:out std_logic;
      mouth1,mouth0,mouth:out std_logic_vector(3 downto 0));
 end mouth;
architecture mm of mouth is
 signal m1,m0,data:std_logic_vector(3 downto 0);
 signal C,clk:std_logic;
 signal ss:std_logic_vector(1 downto 0);
  begin
    process(day,cr,tm)
      begin
        clk<=day or (not tm);
          if clk'event and clk='1' then
              if data=12 then data<="0001";m<='1';
                else data<=data+1;m<='0';
              end if;
          end if;
              if data<=9 then m1<="0000";m0<=data;
                elsif data=10 then m1<="0001";m0<="0000";
                elsif data=11 then m1<="0001";m0<="0001";
                elsif data=12 then m1<="0001";m0<="0010";
               end if;           
     end process;
     mouth1<=m1;mouth0<=m0; mouth<=data;
end;  
 三、日期，個月份的天數不相同，有2月28天（閏年29天），有30天有31天不等：
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity day is
 port(cp,cr,s0,s1:in std_logic;
      day:out std_logic;
      dayh,dayl:out std_logic_vector(3 downto 0));
 end day;
architecture mm of day is
 signal m1,m0:std_logic_vector(3 downto 0);
 signal data:std_logic_vector(4 downto 0);
 signal c:std_logic;
 signal ss:std_logic_vector(1 downto 0);
  begin
    process(cp,cr)
     variable CC:integer;
      begin      
         ss<=s1 & s0;
         case ss is
           when"00"=>CC:=31;
           when"01"=>CC:=30;
           when"10"=>CC:=28;
           when"11"=>CC:=29;
         end case;     
         if cp'event and cp='1' then
                if data=CC then data<="00001";m1<="0000";m0<="0001";c<='1';
                       else data<=data+1;m0<=m0+1;c<='0';
                             if m0=9 then m0<="0000";m1<=m1+1;
                             end if;               
                end if;
         end if;
        if cr='0' then  m1<="0000";m0<="0001";data<="00001";
        end if;
   end process; 
  dayl<=m0;day<=c;dayh<=m1;
end; 
四、時鐘部分，一天24小時
library ieee;
Use ieee.std_logic_1164.all;
Use ieee.std_logic_unsigned.all;
entity timer_day is
   port(cr,min,hor,cp:in std_logic;
        second,day,f500:out std_logic;
        secL,secH,minL,minH,hourL,hourH:out std_logic_vector(3 downto 0));       
end timer_day;
architecture dianzi of timer_day is
 signal display,t0,t1,t2:std_logic_vector(8 downto 0);
 signal c0,c1,c2,s0,s1,m0,m1,h0,h1,clk1,clk2,day0:std_logic;
 signal sq0,sq1,mq0,mq1,hq0,hq1,xs:std_logic_vector(3 downto 0);
begin
    process(cr,cp) --分頻開始
        begin
          if cp'event and cp='1' then
                if t0=499 then t0<="000000000";c0<='1';
                    else t0<=t0+1; c0<='0';
                end if;              
          end if;
          if c0'event and c0='1' then
                if t1=199 then t1<="000000000";c1<='1';
                     else t1<=t1+1;c1<='0';
                end if;              
          end if;
          if c1'event and c1='1' then
                if t2=199 then t2<="000000000";c2<='1';
                   else t2<=t2+1;c2<='0';
                 end if;              
          end if;
      end process;
 --分頻結束 --秒計時開始
     process(c2,cr,min)
         begin
            if c2'event and c2='1' then
                   if sq0=9 then sq0<="0000";s0<='1';
                       else sq0<=sq0+1;s0<='0';
                    end if;                
             end if;
             if s0'event and s0='1' then
                    if sq1=5 then sq1<="0000"; s1<='1';
                        else sq1<=sq1+1;s1<='0';
                    end if;                  
             end if;
             if cr='0' then sq0<="0000";sq1<="0000";
             end if;
             if min='0' then sq0<="0000";sq1<="0000";
             end if;
    end process;--秒計時結束.
    --分開始
    process(s1,min)
       begin
        clk1<=s1 or (not min);--分調整按鈕，按一下分加1同時將秒清0.     
        if  clk1'event and clk1='1' then
              if mq0=9 then mq0<="0000";m0<='1';
                 else mq0<=mq0+1; m0<='0';
               end if;             
         end if;
         if m0'event and m0='1' then
               if mq1=5 then mq1<="0000";m1<='1';
                   else mq1<=mq1+1;m1<='0';
               end if;            
          end if;
           if cr='0' then mq1<="0000";mq0<="0000";
            end if;--分結束
     end process;
    --小時開始
    process(m1,hor)
       begin
        clk2<=m1 or (not hor);--時調整按鈕，按一下小時加1.
        if clk2'event and clk2='1' then day<=day0;
              if hq0=9 then hq0<="0000";h0<='1';
                 else hq0<=hq0+1;h0<='0';
              end if;            
         end if;
         if h0'event and h0='1' then
               if hq1=5 then hq1<="0000";h1<='1';
                   else hq1<=hq1+1;h1<='0';
               end if;             
          end if;
         if  hq1=2 and hq0=3 then day0<='1';
         else day0<='0';
         end if;
         if hq1=2 and hq0=4 then
             hq0<="0000";hq1<="0000";
         end if;
          if cr='0' then hq0<="0000";hq1<="0000";
            end if;--小時結束
     end process;
      secL<=sq0;secH<=sq1;minL<=mq0;minH<=mq1;hourL<=hq0;hourH<=hq1;
      second<=c2;f500<=c0;
end ;
五、顯示部分
      顯示部分如果顯示的數碼管數量有限而顯示的內容又較多，這時應給顯示的內容分組，比如說萬年歷，可以把年月日分為一組，把時分秒分為一組，如果有天氣情況可分為一組，這樣先分組，再顯示實現起來就比較清晰。
一）分組（分兩組），八秒顯示一組，實際中可視情況而定。
library ieee;
Use ieee.std_logic_1164.all;
Use ieee.std_logic_unsigned.all;
entity xuan_dis is
   port(second,yH,yL,tm,Hd,min,hor:in std_logic;
        yH0,yH1,yL0,yL1,mthH,mthL,dH,dL:in std_logic_vector(3 downto 0);
        hH,hL,minH,minL,sH,sL:in std_logic_vector(3 downto 0);
        dis0,dis1,dis2,dis3,dis4,dis5:out std_logic_vector(3 downto 0));
end xuan_dis;
architecture play of xuan_dis is
signal timer:std_logic_vector(3 downto 0);
signal dis:std_logic_vector(5 downto 0);
signal Tnian,TyueD,Tshi:std_logic;
begin
    process(second,yH,yL,tm,Hd,min,hor)
       begin
        dis<=yH&yL&tm&Hd&min&hor;
          if second'event and second='1' then
             timer<=timer+1;
          end if;
          Tnian<=yH and yL;TyueD<=tm and Hd;Tshi<=min and hor;
        if dis="111111" then            
                      if timer>=0 and timer<8 then    dis5<=yL1;dis4<=yL0;dis3<=mthH;dis2<=mthL;dis1<=dH;dis0<=dL;                          
                             else   dis5<=hH;dis4<=hL;dis3<=minH;dis2<=minL;dis1<=sH;dis0<=sL;
                      end if;    
             else
                if Tnian='0' then dis5<=yH1;dis4<=yH0;dis3<=yL1;dis2<=yL0;end if;
                if TyueD='0' then dis5<=mthH;dis4<=mthL;dis3<=dH;dis2<=dL;end if; 
                if Tshi='0' then dis5<=hH;dis4<=hL;dis3<=minH;dis2<=minL;end if;
          end if;     
     end process;
end ;
二）顯示
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity xianshi is
 port(cp:in std_logic;
      p0,p1,p2,p3,p4,p5:in std_logic_vector(3 downto 0);     
      q:out std_logic_vector(6 downto 0);
      w0,w1,w2,w3,w4,w5:out std_logic);
end xianshi;
architecture xianshi of xianshi is
signal timer:std_logic_vector(8 downto 0);
signal xs:std_logic_vector(3 downto 0);
begin
  process(cp)
   begin
  --時間顯示計時
      if cp'event and cp='1' then
           if timer<496 then timer<=timer+1;
              else timer<="000000000";
           end if;
      end if;
   --秒顯示
       if timer>0 and timer<82 then xs<=p0;w0<='0';
                 else w0<='1';
       end if;
       if timer>83 and timer<164 then xs<=p1;w1<='0';
                 else w1<='1';
       end if;
   --分顯示
       if timer>165 and timer<247 then xs<=p2;w2<='0';
                 else w2<='1';
       end if;
       if timer>248 and timer<320 then xs<=p3;w3<='0';
                 else w3<='1';
       end if;
  --時顯示
       if timer>321 and timer<403 then xs<=p4;w4<='0';
                 else w4<='1';
       end if;
       if timer>405 and timer<496 then xs<=p5;w5<='0';
                 else w5<='1';
       end if;
   end process;
process(xs)
      begin
         case xs is
              when "0000"=>q<="0000001";
              when "0001"=>q<="1001111";
              when "0010"=>q<="0010010";
              when "0011"=>q<="0000110";
              when "0100"=>q<="1001100";
              when "0101"=>q<="0100100";
              when "0110"=>q<="0100000";
              when "0111"=>q<="0001111";
              when "1000"=>q<="0000000";
              when "1001"=>q<="0000100";
              when others=>q<="0000001";
          end case;
      end process;--顯示結束
end;