cd.vhd

来自「设计并调试好一个16*16 LED点阵组成的彩灯图案」· VHDL 代码 · 共 40 行

library ieee;
use ieee.std_logic_arith.all;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity cd is
port(clk:in std_logic;
ah:in std_logic_vector(3 downto 0);
qq:out std_logic_vector(15 downto 0));
end cd;
architecture behav of cd is
constant w:integer :=15;
signal q:std_logic_vector(15 downto 0);
begin
process(clk)
variable flag:bit_vector(2 downto 0) :="000";
variable jp1:std_logic :='0';
begin

		if clk'event and clk='1' then
			if flag="000" then
				q<='1' & q(w downto 1);                
				if q(1)='1' and ah="1111" then                             
					flag:="001";
				end if;
			elsif flag="001" then                               
				q<=q(w-1 downto 0) & '0';
				if q(14)='0'  and ah="0000" then
					flag:="010";
				end if;
			elsif flag="010" then                            
				q<="0000000000000000";
         			flag:="000";
			end if;
		end if;
qq<=q;
	end process;
end behav;