speakera.vhd

来自「VHDL实现唱歌的功能」· VHDL 代码 · 共 45 行

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity speakera is
	port(clk :in std_logic;
		 tone :in std_logic_vector(10 downto 0);
		 spks :out std_logic
		 );
end;
architecture one of speakera is
	signal preclk,fullspks :std_logic;
		begin
			divideclk:process(clk)
				variable count4 :std_logic_vector(3 downto 0);
			begin
				preclk<='0';
				if count4>11 then 
					preclk<='1';
					count4:="0000";
				elsif rising_edge(clk) then count4:=count4+1;
				end if;
			end process;
		    genspks:process(preclk,tone)
				variable count11:std_logic_vector(10 downto 0);
			begin
				if rising_edge(preclk) 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 rising_edge(fullspks) then count2:=not count2;
					if count2='1' then spks<='1';
					else spks<='0';
					end if;
				end if;
			end process;
		end;