fen2pin.vhd

用VHDL实现的DDS

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity fen2pin is port
(
   clk :in std_logic;
   sel :out std_logic;
   nsel: out std_logic
);
end fen2pin;
architecture behave of fen2pin is
   signal  half :std_logic;
 begin 
   process(clk)
      begin
     if(clk'event and clk='1')then
      half<= not half;
      end if;
     end process;
   sel<=half;
   nsel<=not half;
end behave;