library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity clock is
    Port ( seg : out std_logic_vector(7 downto 0);
	     a : out std_logic_vector(3 downto 0);--用于選通三極管
	   clk : in std_logic);
end clock;

architecture Behavioral of clock is
signal divcounter: std_logic_vector(27 downto 0);
signal divclk:std_logic;
signal sec_counter1:std_logic_vector(3 downto 0);
signal sec_counter2:std_logic_vector(3 downto 0);
signal min_counter1:std_logic_vector(3 downto 0);
signal min_counter2:std_logic_vector(3 downto 0);


signal scan	: std_logic_vector(8 downto 0);
signal scan_clk: std_logic_vector(1 downto 0);
signal SecSeg1,MinSeg1,SecSeg2,MinSeg2	: std_logic_vector(7 downto 0); 

begin
	--將原始時鐘信號分頻得到1s為周期的時鐘信號divclk
	DIV_CLOCK:process(clk)
	begin
		if clk='1' and clk'event then
			if(divcounter>=X"17D783F")then	
				divcounter<=X"0000000";
				divclk<=not divclk;
			else
				divcounter<=divcounter+'1';
			end if;
		end if;
	end process;
	
	--完成秒和分的計數
	CLOCK:process(divclk)
	begin
		if divclk'event and divclk='1' then
			if(sec_counter1>=X"9") then	
				sec_counter1<=X"0";
				if(sec_counter2>=X"5")then
					sec_counter2<=X"0";
					if(min_counter1>=X"9")then
						min_counter1<=X"0";
						if(min_counter2>=X"5")then
							min_counter2<=X"0";
						else
							min_counter2<=min_counter2+'1';
						end if;
					else
						min_counter1<=min_counter1+'1';
					end if;			
				else
					sec_counter2<=sec_counter2+'1';
				end if;
			else
				sec_counter1<=sec_counter1+'1';
			end if;
		end if;
	end process;

	--產生掃描信號
	SCAN_COUNTER:process(clk)
	begin
		if (clk'event and clk='1') then
			scan<=scan+1;		
		end if;
	end process;
	scan_clk<=scan(8 downto 7);

	--在掃描信號的作用下，輪流選通各個數碼管
	OUT_PUT:process(scan_clk)
	begin
		case scan_clk is
			when "00"=>
				seg<=SecSeg1;
				a<="0001";
			when "01"=>
				seg<=SecSeg2;
				a<="0010";
			when "10"=>
				seg<=MinSeg1;
				a<="0100";
			when "11"=>
				seg<=MinSeg2;
				a<="1000";
			when others=>seg<="11111111";a<="0000";
		end case;
	end process;

	--秒個位驅動數碼管
	SECOND_COUNTER1:process(sec_counter1)
	begin
	  case sec_counter1 is
		when "0000" =>SecSeg1<="00000011";--0
		when "0001" =>SecSeg1<="10011111";--1
		when "0010" =>SecSeg1<="00100101";--2
		when "0011" =>SecSeg1<="00001101";--3
		when "0100" =>SecSeg1<="10011001";--4
		when "0101" =>SecSeg1<="01001001";--5
		when "0110" =>SecSeg1<="01000001";--6
		when "0111" =>SecSeg1<="00011111";--7
		when "1000" =>SecSeg1<="00000001";--8
		when "1001" =>SecSeg1<="00001001";--9
		when others =>SecSeg1<="11111111";
	  end case;
	end process;

	--秒十位驅動數碼管
	SECOND_COUNTER2:process(sec_counter2)
	begin
	  case sec_counter2 is
	    	when "0000" =>SecSeg2<="00000011";--0
	   	when "0001" =>SecSeg2<="10011111";--1
	    	when "0010" =>SecSeg2<="00100101";--2
	    	when "0011" =>SecSeg2<="00001101";--3
	    	when "0100" =>SecSeg2<="10011001";--4
	    	when "0101" =>SecSeg2<="01001001";--5
		when others =>SecSeg2<="11111111";
	  end case;
	end process;

	--隔秒顯示一次分秒之間的點
	DOT_DISPLAY:process(divclk)
	begin  
	 if divclk'event and divclk='1' then
	 	MinSeg1(0)<=not MinSeg1(0);
	 end if;
	end process;

	--分鐘個位驅動數碼管
	MINUTE_COUNTER1:process(min_counter1)
	begin
	  case min_counter1 is
	    	when "0000" =>MinSeg1(7 downto 1)<="0000001";--0
		when "0001" =>MinSeg1(7 downto 1)<="1001111";--1
	    	when "0010" =>MinSeg1(7 downto 1)<="0010010";--2
	    	when "0011" =>MinSeg1(7 downto 1)<="0000110";--3
	    	when "0100" =>MinSeg1(7 downto 1)<="1001100";--4
	    	when "0101" =>MinSeg1(7 downto 1)<="0100100";--5
		when "0110" =>MinSeg1(7 downto 1)<="0100000";--6
	    	when "0111" =>MinSeg1(7 downto 1)<="0001111";--7
	    	when "1000" =>MinSeg1(7 downto 1)<="0000000";--8
	    	when "1001" =>MinSeg1(7 downto 1)<="0000100";--9
		when others =>MinSeg1(7 downto 1)<="1111111";
	  end case;
	end process; 
					
	--分鐘十位驅動數碼管
	MINUTE_COUNTER2:process(min_counter2)
	begin
	  case min_counter2 is
	    	when "0000" =>MinSeg2<="00000011";--0
	 	when "0001" =>MinSeg2<="10011111";--1
	    	when "0010" =>MinSeg2<="00100101";--2
	    	when "0011" =>MinSeg2<="00001101";--3
	    	when "0100" =>MinSeg2<="10011001";--4
	    	when "0101" =>MinSeg2<="01001001";--5
		when others =>MinSeg2<="11111111";
	  end case;
	end process;

end Behavioral;