EEPW论坛

--本实验。按下板上的四个key时。数码管显示得到的数据。
library ieee;
use ieee.std_logic_1164.all;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity KEYLED1 is
PORT ( key_data  : IN  STD_LOGIC_VECTOR(3 DOWNTO 0);
       LED7      : OUT STD_LOGIC_VECTOR(7 DOWNTO 0));
end KEYLED1 ;
 
 ARCHITECTURE behav OF KEYLED1 IS
 signal led_temp: std_logic_vector(3 downto 0);
 BEGIN
  PROCESS( key_data )
  BEGIN
  led_temp<= key_data ;
  CASE  led_temp  IS
   WHEN "1110" =>  LED7 <= "11111110";    --  1
   WHEN "1101" =>  LED7 <= "11111101";    --  2
   WHEN "1011" =>  LED7 <= "11111011";    --  3
   WHEN "0111" =>  LED7 <= "11110111";    --  4
   WHEN OTHERS =>  LED7 <= "11111111";
   --WHEN OTHERS =>  NULL ;
   END CASE ;
  END PROCESS ;
 END behav;