--文件名：TLC7524.VHD
--功能：產生156.25KHz的正弦波。
--最后修改日期：2004.3.18。
library ieee;
use ieee.std_logic_arith.all;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
entity TLC7524 is
port( clk :in std_logic; --系統時鐘
rst :in std_logic; --復位信號
data_out:out std_logic_vector(7 downto 0)); --波形數據
end TLC7524;
architecture behav of TLC7524 is
signal b:integer range 0 to 63; --地址計數器
signal q:integer range 0 to 4; --計數器
signal d:integer range 0 to 255; --波形數據寄存器
begin
process(clk) --此進程通過對系統時鐘的分頻，完成的地址計數器的循環計數
begin
if rst='1' then b<=0; --復位時，對地址寄存器清零
elsif clk'event and clk='1' then
if q=4 then q<=0; --此IF語句完成對系統時鐘的5分頻
if b=63 then b<=0; --此IF語句完成對地址的循環計數
else b<=b+1;
end if;
else q<=q+1;
end if;
end if;
end process;
process(b) --此進程存儲了正弦波64個采樣點的波形數據
begin
case b is
when 00=> d<=255 ; when 01=> d<=254 ;when 02=> d<=252 ;when 03=> d<=249 ;
when 04=> d<=245 ; when 05=> d<=239 ;when 06=> d<=233 ;when 07=> d<=225 ;
when 08=> d<=217 ; when 09=> d<=207 ;when 10=> d<=197 ;when 11=> d<=186 ;
when 12=> d<=174 ; when 13=> d<=162 ;when 14=> d<=150 ;when 15=> d<=137 ;
when 16=> d<=124 ; when 17=> d<=112 ;when 18=> d<= 99 ;when 19=> d<= 87 ;
when 20=> d<= 75 ; when 21=> d<= 64 ;when 22=> d<= 53 ;when 23=> d<= 43 ;
when 24=> d<= 34 ; when 25=> d<= 26 ;when 26=> d<= 19 ;when 27=> d<= 13 ;
when 28=> d<= 8 ; when 29=> d<= 4 ;when 30=> d<= 1 ;when 31=> d<= 0 ;
when 32=> d<= 0 ; when 33=> d<= 1 ;when 34=> d<= 4 ;when 35=> d<= 8 ;
when 36=> d<= 13 ; when 37=> d<= 19 ;when 38=> d<= 26 ;when 39=> d<= 34 ;
when 40=> d<= 43 ; when 41=> d<= 53 ;when 42=> d<= 64 ;when 43=> d<= 75 ;
when 44=> d<= 87 ; when 45=> d<= 99 ;when 46=> d<=112 ;when 47=> d<=124 ;
when 48=> d<=137 ; when 49=> d<=150 ;when 50=> d<=162 ;when 51=> d<=174 ;
when 52=> d<=186 ; when 53=> d<=197 ;when 54=> d<=207 ;when 55=> d<=217 ;
when 56=> d<=225 ; when 57=> d<=233 ;when 58=> d<=239 ;when 59=> d<=245 ;
when 60=> d<=249 ; when 61=> d<=252 ;when 62=> d<=254 ;when 63=> d<=255 ;
when others=> null;
end case;
end process;
data_out<=conv_std_logic_vector(d,8); --正弦波波形數據輸出
end behav;
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