clk_and_modify.vhd

用VHDL语言实现一个能显示时、分、秒的时钟：可分别进行时和分的手动校正；12小时、24小时计时制可选

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

entity clk_and_modify is
port(
     clk1Mh:in std_logic; 
     reset:in std_logic;
     choose:in std_logic;  
     modify_min_hour,div_choose_state:in std_logic; 
     alarm:out std_logic;        
     sec_one:out integer range 0 to 9; 
     sec_ten:out integer range 0 to 5;
     min_one:out integer range 0 to 9; 
     min_ten:out integer range 0 to 5;
     hour_one:out integer range 0 to 9;     
     hour_ten:out integer range 0 to 2;
     
     alarm_modify:in std_logic;
     ch_state:out std_logic
     );
end;

architecture arch of clk_and_modify is
  signal sec_l,min_l,hour_l,min_l_alarm,hour_l_alarm:integer range 0 to 9;
  signal sec_h,min_h,min_h_alarm: integer range 0 to 5;   
  signal hour_h,hour_h_alarm: integer range 0 to 2;
  signal choose_state :  std_logic; 
  begin
  p1:process(clk1Mh,reset)                                
     begin 
     if reset='1' then                      --有复位信号就全清0
        sec_l<=0;sec_h<=0;
        min_l<=0;min_h<=0;
        hour_l<=0;hour_h<=0;   

     elsif rising_edge(clk1Mh)then
          if(choose='0') then              --choose键未拨上去则正常计时
             if sec_l<9 then
                   sec_l<=sec_l+1;--alarm<='0';
             elsif(sec_l=9 and sec_h<5 )then
                   sec_l<=0;sec_h<=sec_h+1;--alarm<='0';
             elsif(sec_l=9 and sec_h=5) then        --秒加到60则变为0，分加1
                   sec_l<=0;sec_h<=0;
                if min_l<9 then
                   min_l<=min_l+1;--alarm<='0';
                elsif(min_l=9 and min_h<5 )then
                   min_l<=0;min_h<=min_h+1;--alarm<='0';
                elsif(min_l=9 and min_h=5) then
                   min_l<=0;min_h<=0;--alarm<='1'; --分加到60则变为0，时加1，报时信号为1
                    if(hour_l=3 and hour_h=2 )then
                       hour_l<=0;hour_h<=0;
                    elsif(hour_l<3 and hour_h=2)then
                       hour_l<=hour_l+1;
                    elsif(hour_l=9 and hour_h<2) then 
                       hour_l<=0;hour_h<=hour_h+1;
                    elsif(hour_l<9 and hour_h<2) then 
                       hour_l<=hour_l+1;
                    else null;
                    end if;
                else null;
                end if;
             else null;
             end if;  

          elsif(modify_min_hour='1')then--choose拨上时若modify_min_hour也按下，则通过choose_state来判断时和分哪个量增加
         
              case choose_state is
                   when '1' => if min_l<9 then           --分钟调整
                                  min_l<=min_l+1;
                               elsif(min_l=9 and min_h<5) then
                                  min_l<=0; min_h<=min_h+1;
                               elsif(min_l=9 and min_h=5 )then
                                  min_l<=0;min_h<=0;
                               else null;
                               end if;
                   when '0' => if(hour_l=3 and hour_h=2 )then --小时调整
                                  hour_l<=0;  hour_h<=0;
                               elsif(hour_l<3 and hour_h=2)then
                                  hour_l<=hour_l+1;
                               elsif(hour_l=9 and hour_h<2) then 
                                  hour_l<=0;hour_h<=hour_h+1;
                               elsif(hour_l<9 and hour_h<2) then 
                                  hour_l<=hour_l+1;
                               else null;
                               end if;
                   when others=> null;
              end case;             
          else null;   
          end if;        

          if alarm_modify='0' then            --设定闹钟，选择该被输出的信号
             sec_one<=sec_l;
             sec_ten<=sec_h;                  --时钟输出
             min_one<=min_l;
             min_ten<=min_h;
             hour_one<=hour_l;
             hour_ten<=hour_h; 
          else
             
             if modify_min_hour='1' then
                --choose_state<='1';
                case choose_state is
                   when '1' =>if min_l_alarm<9 then
                                 min_l_alarm<=min_l_alarm+1;
                              elsif(min_l_alarm=9 and min_h_alarm<5) then
                                 min_l_alarm<=0; min_h_alarm<=min_h_alarm+1;
                              elsif(min_l_alarm=9 and min_h_alarm=5 )then
                                 min_l_alarm<=0;min_h_alarm<=0;
                              else null;
                              end if;
                   when '0' =>if(hour_l_alarm=3 and hour_h_alarm=2 )then
                                  hour_l_alarm<=0;  hour_h_alarm<=0;
                                elsif(hour_l_alarm<3 and hour_h_alarm=2)then
                                  hour_l_alarm<=hour_l_alarm+1;
                                elsif(hour_l_alarm=9 and hour_h_alarm<2) then 
                                  hour_l_alarm<=0;hour_h_alarm<=hour_h_alarm+1;
                                elsif(hour_l_alarm<9 and hour_h_alarm<2) then 
                                  hour_l_alarm<=hour_l_alarm+1;
                                else null;
                                end if;
                   when others=> null;
                end case;   
             else null;
             end if;
          
             min_one<=min_l_alarm;          --闹钟输出
             min_ten<=min_h_alarm;
             hour_one<=hour_l_alarm;
             hour_ten<=hour_h_alarm;                        
          end if;                   
     else null;
     end if;     

     if( sec_l=1 and sec_h=0 and min_l=0 and min_h=0 and choose='0')
         or(sec_l=2 and sec_h=0 and min_l=0 and min_h=0 and choose='0')
         
or(sec_l=1 and sec_h=0 and min_l=min_l_alarm and min_h=min_h_alarm and hour_l=hour_l_alarm and hour_h=hour_h_alarm)
or(sec_l=2 and sec_h=0 and min_l=min_l_alarm and min_h=min_h_alarm and hour_l=hour_l_alarm and hour_h=hour_h_alarm)         
or(sec_l=3 and sec_h=0 and min_l=min_l_alarm and min_h=min_h_alarm and hour_l=hour_l_alarm and hour_h=hour_h_alarm)
or(sec_l=4 and sec_h=0 and min_l=min_l_alarm and min_h=min_h_alarm and hour_l=hour_l_alarm and hour_h=hour_h_alarm)
or(sec_l=5 and sec_h=0 and min_l=min_l_alarm and min_h=min_h_alarm and hour_l=hour_l_alarm and hour_h=hour_h_alarm) then
         alarm<='1';            --整点，定点报时
     else alarm<='0';
     end if; 
     ch_state<=choose_state;
     end process;

     p2: process(div_choose_state)                      --选择时、分
             begin
                if(div_choose_state'event and div_choose_state='1') then 
                 choose_state<=not choose_state;        
                end if;
     end process;
 end;