frequency_div.vhdl

相位差测试

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity fdiv is
   Generic (  rate : integer :=10  );
   Port    (  f_in : In  std_logic;
	     f_out : Out std_logic );
end;
architecture behavioral of fdiv is
   signal cnt : integer range 0 to rate := 0;
   signal clk : std_logic:='0';
begin
   process (f_in)
   begin
      if f_in'event and f_in = '1' then
	 if cnt /= rate then
	    cnt <= cnt + 1;
	 else
	    cnt <= 1;
	    clk<=not clk;
	 end if;
      end if;
   end process;
f_out <= clk;
end behavioral;