msecond.vhd

读取4*4键盘的键值

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;
entity msecond is
port(
		clk, reset,set    : in	std_logic;
		ensec             : out	std_logic;
		daout             : out  std_logic_vector (7 downto 0));
END entity msecond ;

architecture fun of msecond  IS
signal count: std_logic_vector( 7 downto 0);
begin
daout <= count;

process ( clk , reset ,set ) 
begin   
if (reset='1') then
count <= "00000000";
elsif (set='0')then
    if (clk'event and clk='1') then
     if (count(3 downto 0)="1001") then
            if (count <"10100000") then
                 if (count="10011001") then
                 ensec <='1'; 
                  count<="00000000";           				          		           	   		
           	   		else
           	   		   count<=count+7; 
           	   		end if;
             else 
              count<="00000000";
             end if;
     elsif (count < "10100000") then 
        count <= count+1;
        ensec <='0';               
        else 
        count<="00000000";                  
        end if; 
      end if;          
end if;
end process;
end fun;