display.vhd

用层次化设计完成倒计时装置 输入：16位二进制倒计时起始数字、倒计时起始数字的输入使能信号、 倒计时开始信号、复位信号、1MHz时钟信号、10Hz时钟信号。 输出：数码管数据信号及宣统信号

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

entity display is
port(
	clk: in std_logic;
	data: in std_logic_vector (15 downto 0);
	s_over: in std_logic;
	sel: out std_logic_vector (5 downto 0);
	leds: out std_logic_vector (7 downto 0);
	over: out std_logic
	);
end display;

architecture behaver of display is
	signal templeds: std_logic_vector (3 downto 0);	-- 8 led lamp ctl
begin
	process (clk,s_over)	-- overflow flag
	begin
--		if s_over'event and s_over='1' then
--			over
--			if reset='0'
--		if clk'event and clk='1' then
			if s_over='1' then
				over<='1';
			else
				over<='0';
			end if;
--		end if;
	end process;

	process (clk)			-- sel controler
		variable tempi: integer range 0 to 5;
	begin
		if clk'event and clk='1' then
			if tempi<3 then		-- use 4bits
				tempi:=tempi+1;
			else
				tempi:=0;
			end if;
		end if;
		case tempi is
			when 0 => sel<="011111";	templeds<=data(7 downto 4);		-- 101111
			when 1 => sel<="101111";	templeds<=data(11 downto 8);	-- 110111
			when 2 => sel<="110111";	templeds<=data(15 downto 12);	-- 111011
			when 3 => sel<="111011";	templeds<=data(3 downto 0);		-- 011111
			when 4 => sel<="111101";
			when 5 => sel<="111110";
			when others => sel<="111111";
		end case;
	end process;
	
	process (clk)		-- for displaying on 8_leds
	begin
		if clk'event and clk='1' then
			case templeds is
				when "0000" => leds(7 downto 0)<="00111111";
				when "0001" => leds(7 downto 0)<="00000110";
				when "0010" => leds(7 downto 0)<="01011011";
				when "0011" => leds(7 downto 0)<="01001111";
				when "0100" => leds(7 downto 0)<="01100110";
				when "0101" => leds(7 downto 0)<="01101101";
				when "0110" => leds(7 downto 0)<="01111101";
				when "0111" => leds(7 downto 0)<="00000111";
				when "1000" => leds(7 downto 0)<="01111111";
				when "1001" => leds(7 downto 0)<="01101111";
				when "1010" => leds(7 downto 0)<="01110111";
				when "1011" => leds(7 downto 0)<="01111100";
				when "1100" => leds(7 downto 0)<="00111001";
				when "1101" => leds(7 downto 0)<="01011110";
				when "1110" => leds(7 downto 0)<="01111001";
				when "1111" => leds(7 downto 0)<="01110001";
				when others => leds(7 downto 0)<="10000000";
			end case;
		end if;
	end process;
end behaver;