Cours:TP printempsM4209 TP 2 Corr

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Exercice 1

-- description du composant compteur/decompteur cascadable
library ieee;
use ieee.std_logic_1164.all;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity compteurbcd is port (
		clk :in std_logic;
		en : in std_logic;
		init : in std_logic;
--ud=1 up, ud=0 down
		ud : in std_logic;
		enout : out std_logic;
		s: out std_logic_vector(3 downto 0)
		);
end entity;
	
architecture behavior of compteurbcd is
	signal n : std_logic_vector(3 downto 0);
	begin
	increment : process(clk) begin
          if clk'event and clk='1' then
            if init ='1' then
              n <= (others => '0');
            elsif en='1' then
              if ud = '1' then  --up
                if n<9 then
                  n <= n + 1 ;
                else
                  n <= (others => '0');
                end if;
              else -- down
                if n>0 then 
                   n <= n - 1;
                else
                   n <= "1001";
                end if;
              end if;
            end if;	
          end if;
	end process;
-- gestion enout
   enout <= '1' when en='1' and ud='1' and n=9 else
	    '1' when en='1' and ud='0' and n=0 else
            '0';
   s <= n;
end behavior;