tonetaba.vhd

来自「总体演示程序DEMO_FPGA.rar」· VHDL 代码 · 共 32 行

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
ENTITY ToneTaba IS
    PORT ( Index :  IN INTEGER RANGE 0 TO 15;
           CODE  : OUT std_logic_vector(2 downto 0);
           HIGH  : OUT STD_LOGIC; 
           Tone  : OUT INTEGER RANGE 0 TO 16#7FF#  );
END;
ARCHITECTURE one OF ToneTaba IS
BEGIN
    Search : PROCESS(Index)
    BEGIN
        CASE Index IS              -- 译码电路，查表方式，控制音调的预置数
            WHEN 0  => Tone <= 2047; CODE <= "000"; HIGH <= '0';  
            WHEN 1  => Tone <= 773;  CODE <= "001"; HIGH <= '0';  
            WHEN 2  => Tone <= 912;  CODE <= "010"; HIGH <= '0';  
            WHEN 3  => Tone <= 1036; CODE <= "011"; HIGH <= '0';  
            WHEN 5  => Tone <= 1197; CODE <= "100"; HIGH <= '0';  
            WHEN 6  => Tone <= 1290; CODE <= "101"; HIGH <= '0';  
            WHEN 7  => Tone <= 1372; CODE <= "110"; HIGH <= '0';  
            WHEN 8  => Tone <= 1410; CODE <= "000"; HIGH <= '1';  
            WHEN 9  => Tone <= 1480; CODE <= "001"; HIGH <= '1';  
            WHEN 10 => Tone <= 1542; CODE <= "010"; HIGH <= '1';  
            WHEN 12 => Tone <= 1622; CODE <= "011"; HIGH <= '1';  
            WHEN 13 => Tone <= 1668; CODE <= "100"; HIGH <= '1';  
            WHEN 15 => Tone <= 1728; CODE <= "000"; HIGH <= '1';  
            WHEN OTHERS => NULL;
        END CASE;
    END PROCESS;
END;