Aviso: Este post fue migrado desde mi blog viejo de mis tiempos de universitario. Cabe resaltar que, por solicitud del profesor que impartió la clase, el código aquí mostrado tiene fallos intencionales.

Control de acceso con contraseña, utilizando FPGA Spartan 3E y Nexys 2

Código

library IEEE;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_1164.ALL;

use IEEE.NUMERIC_STD.ALL;

entity contador is
port (
clk: in std_logic;
btnUp: in std_logic;
btnDown: in std_logic;
btnReset: in std_logic;
vrgzaUp: in std_logic;
vrgzaDown: in std_logic;
an: out std_logic_vector(3 downto 0);
seg: out std_logic_vector(6 downto 0);
dp: out std_logic
);
end contador;

architecture Behavioral of contador is
type estados is (sumar,neutral,restar);
signal pre,fut: estados;

signal mult: std_logic_vector(1 downto 0):="00";

signal N: std_logic_vector (3 downto 0):="0000";
signal a: std_logic_vector(3 downto 0):="0000";
signal b: std_logic_vector(3 downto 0):="0000";
signal c: std_logic_vector(3 downto 0):="0000";
signal d: std_logic_vector(3 downto 0):="0000";
signal pulsoDisp: std_logic;
signal pulsoVrgza: std_logic;
signal contador1: integer range 0 to 100000 := 0;

begin
dp<='1';
 with N select
 seg<="0000001" when "0000",
    "1001111" when "0001",
    "0010010" when "0010",
    "0000110" when "0011",
    "1001100" when "0100",
    "0100000" when "0110",
    "0001111" when "0111",
    "0000000" when "1000",
    "0000100" when "1001",
  "1111111" when others;

  
 divisorFrecuencia: process (clk)
 begin
 if rising_edge(clk) then
  if contador1=100000 then
   pulsoDisp <= not pulsoDisp;
   contador1<=0;
  else
   contador1<=contador1 + 1;
  end if; 
  
 end if;
 end process divisorFrecuencia;

 
 pro1: process (pulsoDisp)
 variable control: std_logic:='0';
 variable contint: integer range 0 to 10;
 begin
 if rising_edge(plusoDisp) then
 contint:= contint+1;
 if contint=10 then
  if (vrgzaUp='0' and vrgzaDown='0') then
   a<=a;
 elsif (vrgzaUp='0' and vrgzaDown='1') then
 
  end if;
 end process pro2;

end Behavioral;