jk.vhd

VHDL子程序集,包括各种例程资料以及源码.

--******************************
--* JK Flip Flop (CASE .. IS)  *
--*       Filename : JK        *
--******************************

library IEEE;
use IEEE.std_logic_1164.all;

entity JK is
    port (
          J:     in STD_LOGIC;
          K:     in STD_LOGIC;
          CLK:   in STD_LOGIC;
          RESET: in STD_LOGIC;
          Q:     out STD_LOGIC;
          Q_Bar: out STD_LOGIC
         );
end JK;

architecture JK_arch of JK is
signal S:STD_LOGIC_VECTOR (1 downto 0);
signal Qout:STD_LOGIC;
begin
    S <= J & k;
Process (CLK,RESET,Qout)

begin
    if RESET = '1' then
       Qout <= '0';
    elsif CLK'event and CLK = '1' then
    case S is
       when "11"   => Qout <= not Qout;
       when "01"   => Qout <= '0';
       when "10"   => Qout <= '1';
       when others => null;
    end case;
    end if;
Q <= Qout;
Q_Bar <= not Qout;     
end process;
        
end JK_arch;