asm_led.vhd

本程序是一个用VHDL编写的数码管扫描显示控制器的设计与实现的程序

Library IEEE; 
--Declaration of using STD_LOGIC_1164 package          
Use IEEE.std_logic_1164.all; 
Use IEEE.std_logic_unsigned.all;
use ieee.std_logic_arith.all;
entity asm_led is
port(
clk: in STD_LOGIC;
reset: in STD_LOGIC;
 c:inout std_logic_vector(3 downto 0);
catn: out STD_LOGIC_VECTOR(5 downto 0);
d:out std_logic_vector(6 downto 0));
    
end asm_led;
architecture  lightarch of asm_led is
signal x:std_logic_vector(5 downto 0):="111111";
component transform                     
 Port( ai:in std_logic_vector(3 downto 0);   
  b:out std_logic_vector(6 downto 0));   
  End component transform;
begin
u1: transform port map(c,d);
process (clk,reset)
begin
if (reset='1') then
catn<="111111";
elsif (clk'event and clk='1')then
case x is 
when"111111"=>x<="111110";c<="0000";
when"111110"=>x<="111101";c<="0001";
when"111101"=>x<="111011";c<="0010";
when"111011"=>x<="110111";c<="0011";
when"110111"=>x<="101111";c<="0100";
when"101111"=>x<="011111";c<="0101";
when"011111"=>x<="111110";c<="0000";
when others=>x<="111110";c<="0000";
end case ;
end if;
catn<=x;
end process;
end;