Subversion Repositories simple_fm_receiver

-- ------------------------------------------------------------------------
-- Copyright (C) 2004 Arif Endro Nugroho
-- All rights reserved.
-- 
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
-- 
-- 1. Redistributions of source code must retain the above copyright
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-- 2. Redistributions in binary form must reproduce the above copyright
--    notice, this list of conditions and the following disclaimer in the
--    documentation and/or other materials provided with the distribution.
-- 
-- THIS SOFTWARE IS PROVIDED BY ARIF ENDRO NUGROHO "AS IS" AND ANY EXPRESS
-- OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
-- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-- DISCLAIMED. IN NO EVENT SHALL ARIF ENDRO NUGROHO BE LIABLE FOR ANY
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-- ------------------------------------------------------------------------
 
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
 
entity fm is
 port (
  CLK                     : in  bit;
  RESET                   : in  bit;
  FMIN                    : in  bit_vector (07 downto 0);
  DMOUT                   : out bit_vector (11 downto 0)
  );
end fm;
 
architecture structural of fm is
 component nco
  port (
       clock              : in  bit;
       clear              : in  bit;
       input_nco          : in  bit_vector (17 downto 0);
       offset             : in  bit_vector (17 downto 0);
       output_nco         : out bit_vector (07 downto 0)
       );
 end component;
 component loop_filter
  port (
       input_loop         : in  bit_vector (07 downto 0);
       clock              : in  bit;
       output_loop        : out bit_vector (11 downto 0);
       clear              : in  bit
       );
 end component;
 component phase_detector
  port (
       clock              : in  bit;
       signal_input       : in  bit_vector (07 downto 0);
       signal_nco         : in  bit_vector (07 downto 0);
       phase_output       : out bit_vector (07 downto 0)
       );
 end component;
 component fir
  port (
       clock              : in  bit;
       clear              : in  bit;
       fir_in             : in  bit_vector (11 downto 0);
       dmout              : out bit_vector (11 downto 0)
       );
 end component;
-- internal signal
signal loop_out           : bit_vector (11 downto 0);
signal input_nco          : bit_vector (17 downto 0);
signal offset             : bit_vector (17 downto 0);
signal output_nco         : bit_vector (07 downto 0);
signal phase_output       : bit_vector (07 downto 0);
 
begin
-- offset values 1/16 equ B"000100000000000000" <18,0,u>
offset (17) <= '0' ;
offset (16) <= '0' ;
offset (15) <= '0' ;
offset (14) <= '1' ;
offset (13) <= '0' ;
offset (12) <= '0' ;
offset (11) <= '0' ;
offset (10) <= '0' ;
offset (9)  <= '0' ;
offset (8)  <= '0' ;
offset (7)  <= '0' ;
offset (6)  <= '0' ;
offset (5)  <= '0' ;
offset (4)  <= '0' ;
offset (3)  <= '0' ;
offset (2)  <= '0' ;
offset (1)  <= '0' ;
offset (0)  <= '0' ;
 
-- The constant that have big effect on the PLL loop.
-- This constant have big effect on system response, high values. (e.g 1/16),
-- will make the system have fast response time (e.g. quickly change state).
-- Otherwise if low values applied to this (e.g 1/32) will make the system
-- little slow response time but have smooth look's. Change it's as you like
-- to see the effect's. ^_^
 
input_nco (17) <= loop_out(11); -- 1
input_nco (16) <= loop_out(11); -- 1/2
input_nco (15) <= loop_out(11); -- 1/4
input_nco (14) <= loop_out(11); -- 1/8
input_nco (13) <= loop_out(11); -- 1/16
input_nco (12) <= loop_out(11); -- 1/32
input_nco (11) <= loop_out(10); -- 1/64
input_nco (10) <= loop_out(09); -- 1/128
input_nco (09) <= loop_out(08); -- 1/256
input_nco (08) <= loop_out(07); -- 1/512
input_nco (07) <= loop_out(06); -- 1/1024
input_nco (06) <= loop_out(05);
input_nco (05) <= loop_out(04);
input_nco (04) <= loop_out(03);
input_nco (03) <= loop_out(02);
input_nco (02) <= loop_out(01);
input_nco (01) <= loop_out(00);
input_nco (00) <= loop_out(11);
 
-- end divider 
mynco : nco 
    port map (
    clock                      => CLK,
    clear                      => RESET,
    input_nco                  => input_nco,
    offset                     => offset,
    output_nco ( 7 downto 0)   => output_nco
    );
myfir : fir 
    port map (
    clock                      => CLK,
    clear                      => RESET,
    fir_in                     => loop_out,
    dmout (11 downto 0)        => DMOUT
    );
myphase : phase_detector 
    port map (
    clock                      => CLK,
    signal_input               => FMIN,
    signal_nco                 => output_nco,
    phase_output ( 7 downto 0) => phase_output
    );
myloop : loop_filter 
    port map (
    input_loop                 => phase_output,
    clock                      => CLK,
    output_loop (11 downto 0)  => loop_out,
    clear                      => RESET
    );
end structural;