Subversion Repositories instruction_list_pipelined_processor_with_peripherals

library IEEE;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.math_real.all;

use ieee.std_logic_unsigned.all;

entity uartBrg is

  generic (

    DIVISOR: natural := 32000000/(16*9600) -- DIVISOR = 100,000,000 / (16 x BAUD_RATE)

    -- 2400 -> 2604

    -- 9600 -> 651

    -- 115200 -> 54

    -- 1562500 -> 4

    -- 2083333 -> 3

  );

  port (

    clk: in std_logic;                         -- clock

    reset: in std_logic;                      -- reset

         outp : out std_logic

  );

end uartBrg;

architecture Behavioral of uartBrg is

  constant COUNTER_BITS : natural := integer(ceil(log2(real(DIVISOR))));

  signal sample: std_logic; -- 1 clk spike at 16x baud rate

  signal sample_counter: std_logic_vector(COUNTER_BITS-1 downto 0) := (others=> '0'); -- should fit values in 0..DIVISOR-1

begin

  -- sample signal at 16x baud rate, 1 CLK spikes

  sample_process: process (clk,reset) is

  begin

    if reset = '1' then

      sample_counter <= (others => '0');

      sample <= '0';

    elsif rising_edge(clk) then

      if sample_counter = DIVISOR-1 then

        sample <= '1';

        sample_counter <= (others => '0');

      else

        sample <= '0';

        sample_counter <= sample_counter + 1;

      end if;

    end if;

  end process;

  outp <= sample;

end Behavioral;