speakera.vhd

来自「用VHDL编写的播放器」· VHDL 代码 · 共 45 行

library ieee;
use ieee.std_logic_1164.all;

entity speakera is
  port( clk: in std_logic;
        tone: in integer range 0 to 16#7FF#;
         spks: out std_logic);
end;

architecture one of speakera is
   signal preclk :std_logic;
   signal fullspks: std_logic;
 begin
   divideclk: process(clk)
    variable count4: integer range 0 to 15;
      begin
         preclk<='0';
         if count4>11 then preclk<='1';count4:=0;
         elsif clk'event and clk='1' then count4:=count4+1;
         end if;
     end process;
   genspks: process(preclk ,tone)
     variable count11: integer range 0 to 16#7FF#;
  begin
    if preclk'event and preclk='1' then
       if count11=16#7FF# then
          count11:=tone;
          fullspks<='1';
       else count11:=count11+1;
          fullspks<='0'; end if;
    end if ;
  end process;
  delayspks:process(fullspks)
     variable count2: std_logic;
begin
    if  fullspks'event and fullspks='1' then 
       count2:= not count2;
      if count2='1' then spks<='1';
      else spks<='0'; end if;
    end if;
  end process;
end;