clock.vhd

基于Quartus II FPGA/CPLD数字系统设计实例（VHDL源代码文件）

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity clock is
port(clk:in std_logic;-----时钟输入 20mhz
     clr:in std_logic;-----清零信号
     en:in std_logic;------暂停信号
     mode:in std_logic;----控制信号，用于选择模式
     inc:in std_logic;-----置数信号
     seg7:out std_logic_vector(6 downto 0);-----数码管显示信号
     scan:out std_logic_vector(5 downto 0));---数码管扫描信号
end;
architecture one of clock is
    signal state:std_logic_vector(1 downto 0);------定义四种状态
	signal qhh,qhl,qmh,qml,qsh,qsl:std_logic_vector(3 downto 0);---小时、分、秒的高位和低位
	signal data:std_logic_vector(3 downto 0);
	signal cnt:integer range 0 to 5;-------------扫描数码管的计数器
	signal clk1khz,clk1hz,clk2hz:std_logic;------1khz、1hz、2hz的分频信号
	signal blink:std_logic_vector(2 downto 0);---闪烁信号
	signal inc_reg:std_logic;
	signal sec,min:integer range 0 to 59;
	signal hour:integer range 0 to 23;
begin
----------------------------------1khz分频，用于扫描数码管地址
process(clk)
variable count:integer range 0 to 0;
begin
if clk'event and clk='1' then 
  if count=0 then clk1khz<=not clk1khz;count:=0;
  else count:=count+1;
  end if;
end if;
end process;
------------------------------------1Hz分频，用于计时
process(clk1khz)
variable count:integer range 0 to 1;
begin
if clk1khz'event and clk1khz='1' then 
  if count=1 then clk1hz<=not clk1hz;count:=0;
  else count:=count+1;
  end if;
end if;
end process;
--------------------------------------2Hz分频，用于数码管闪烁
process(clk1khz)
variable count:integer range 0 to 0;
begin
if clk1khz'event and clk1khz='1' then 
  if count=0 then clk2hz<=not clk2hz;count:=0;
  else count:=count+1;
  end if;
end if;
end process;
-----------------------------模式转换
process(mode,clr)
begin
if clr='1' then
    state<="00";
elsif mode'event and mode='1' then
	state<=state+1;
end if;
end process;
-------------------------状态控制
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;--------------------------模式0，正常计时
		             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 ---------------------------模式1，设定小时时间
	               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 ---------------------------模式2，设定分钟时间
	               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 ---------------------------模式3，设定秒钟时间
	               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;
-----------------------------当进行时间设定时，令数码管闪烁---------
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;
---------------------------秒计数的十进制转BCD码--------
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";
	when others=>null;
end case;
end process;
---------------------------分计数的十进制转BCD码---------
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";
	when others=>null;
end case;
end process;
---------------------------小时计数的十进制转BCD码---------
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;
----------------------------------------数码管动态扫描计数----------------------
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;
-------------------------------------数码管动态扫描-----------
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<="000001";
	when 1=> data<=qsh or (blink(0)&blink(0)&blink(0)&blink(0));scan<="000010";
	when 2=> data<=qml or (blink(1)&blink(1)&blink(1)&blink(1));scan<="000100";
	when 3=> data<=qmh or (blink(1)&blink(1)&blink(1)&blink(1));scan<="001000";
	when 4=> data<=qhl or (blink(2)&blink(2)&blink(2)&blink(2));scan<="010000";
	when 5=> data<=qhh or (blink(2)&blink(2)&blink(2)&blink(2));scan<="100000";
	when others=>null;
end case;
end process;  
-----------------------------------------七段译码--------------------
process(data)
begin
case data is
    when"0000"=>seg7<="1111110";
	when"0001"=>seg7<="0110000";
	when"0010"=>seg7<="1101101";
	when"0011"=>seg7<="1111001";
	when"0100"=>seg7<="0110011";
	when"0101"=>seg7<="1011011";
	when"0110"=>seg7<="1011111";
	when"0111"=>seg7<="1110000";
	when"1000"=>seg7<="1111111";
	when"1001"=>seg7<="1111011";
    when others=>seg7<="0000000";
end case;
end process;
end;