show.vhd

1、 南北和东西方向各有一组绿、黄、红灯

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

entity show is
	port(		clk	 : in std_logic;
				time1:  in std_logic_vector(5 downto 0);
                time2 : in std_logic_vector(5 downto 0);
				sel : out std_logic_vector(1 to 4);
				show:out std_logic_vector(0 to 6));
end show;

architecture a of show is
	signal i : std_logic_vector(3 downto 0);
	signal sel1 : std_logic_vector(1 to 4);
begin
	process(clk)                          
	begin 
		if (clk'event and clk='1')then            ---片选信号：时分复用
			case sel1 is
				when "0111"=>
					sel1<="1110";
					i<="00"&time1(5 downto 4);
                when "1110"=>
                    sel1<="1101";
                    i<=time1(3 downto 0);
                when "1101"=>
                    sel1<="1011";
                    i<="00"&time2(5 downto 4);
				when "1011"=>
					sel1<="0111";
					i<=time2(3 downto 0);
                when others=>
                    sel1<="0111";
			end case;
		end if;
	end process;

	sel<=sel1;
	show <=         "1110011" when i="1001" else
					"1111111" when i="1000" else
					"1110000" when i="0111" else
					"0011111" when i="0110" else
					"1011011" when i="0101" else
					"0110011" when i="0100" else
					"1111001" when i="0011" else
					"1101101" when i="0010" else
					"0110000" when i="0001" else
					"1111110";
end;