cnt10.vhd

led 跑马灯

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity cnt10 is
port(	clrn,clk,en : in std_logic;
		led7s: out std_logic_vector(6 downto 0)
	);
end cnt10;
architecture a of cnt10 is
signal tmp : std_logic_vector(3 downto 0);
begin
process( clk,clrn,tmp)
begin
	if  clrn ='0' then tmp<="0000";
	elsif (clk'event and clk='1') then
		if en='1' then
	if tmp<7 then tmp<=tmp + 1;
	else tmp<="0000";
	end if;
   end if;
  end if;
case tmp is
	when "0001"=> led7s<="0000001";
	when "0010"=> led7s<="0000010";
	when "0011"=> led7s<="0000100";
	when "0100"=> led7s<="0001000";
	when "0101"=> led7s<="0010000";
	when "0110"=> led7s<="0100000";
	when "0111"=> led7s<="1000000";
	when others => led7s<="0000000";
end case;
end process;
end a;