cnt8.vhd

DE2板上的hello程序,实现在8个七段译码器上循环显示hello

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;


entity cnt8 is               --对输入进行转换,能使下一个7段译码器的输入等到改变
	port
		( 
         add8 : in  std_logic_vector(2 downto 0);
	     cout : out std_logic_vector(2 downto 0)
		);
end cnt8;


architecture bhav of cnt8 is
	
	signal cqi : std_logic_vector(2 downto 0);
	
	begin
		process(add8)			
			begin
				case add8 is
					when "000" => cqi<="111";       --O  -> 无
					when "111" => cqi<="110";       --无 -> 无
					when "110" => cqi<="101";       --无 -> 无
					when "101" => cqi<="100";       --无 -> H
					when "100" => cqi<="011";       --H  -> E
					when "011" => cqi<="010";       --E  -> L
					when "010" => cqi<="001";       --L  -> L
					when "001" => cqi<="000";       --L  -> O
					when others => NULL;
				end case;
				
			cout <= cqi;
		end process;
end bhav;