fp.vhd

这是一个通过外部按键来控制发光二极管发光的程序

--分频模块,改变N值,可以得到不同频率的时钟
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY fp IS
GENERIC (N:integer);
PORT(clk:IN STD_LOGIC;--全局时钟,25M
  clkout:OUT STD_LOGIC);
END fp;

ARCHITECTURE rtl OF fp IS
signal count:integer range 0 to N-1;
signal clkout1:std_logic;
begin

 process(clk)
 begin 
	if(clk'event and clk='1') then
	  if(count=N-1)then
		 count<=0;
	  else	
		 count<=count+1;
	  end if;
	end if;
 end process;

 process(clk,count)
  begin	
     if(clk'event and clk='1') then
		if (count<(integer(N/2))) then
			clkout1<='0';
		else
			clkout1<='1';
		end if;
	end if;
 end process;
clkout<=clkout1;
end rtl;