conta_up

-- Contador de década sobe e desce
-- Entradas: clk (clock), reset;
-- Saída: q (Vetor 4 posições tipo BCD)
-- Autores: João Vitor e Marcos Meira
-- 02/08/2017

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;

entity conta_up is
  port (
    clk:in bit;
    reset: in bit;
     carry_out: out bit;
    q: out std_logic_vector(3 downto 0)
    );
end conta_up;

architecture arquitetura of conta_up is
begin
    process(clk,reset)
    variable qtemp: std_logic_vector(3 downto 0);
    begin
        if reset='1' then
        qtemp:="0000";

        else
            if clk'event and clk='1' then

                    if qtemp<9 then     ---
                    qtemp:=qtemp+1;      ---
                    carry_out <= '0';       ---
                    else                        ---     CONTADOR CRESCENTE
                    qtemp:="0000";       ---
                    carry_out <= '1';       ---
                    end if;                 ---


            end if;
        q<=qtemp;
        end if;
    end process;
end arquitetura;