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-- $Id: s6_cmt_sfs_unisim.vhd 649 2015-02-21 21:10:16Z mueller $

--

-- Copyright 2013- by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>

--

-- This program is free software; you may redistribute and/or modify it under

-- the terms of the GNU General Public License as published by the Free

-- Software Foundation, either version 2, or at your option any later version.

--

-- This program is distributed in the hope that it will be useful, but

-- WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

-- for complete details.

--

------------------------------------------------------------------------------

-- Module Name:    s6_cmt_sfs - syn

-- Description:    Spartan-6 CMT for simple frequency synthesis

--                 Direct instantiation of Xilinx UNISIM primitives

--

-- Dependencies:   -

-- Test bench:     -

-- Target Devices: generic Spartan-6

-- Tool versions:  xst 14.5-14.7; ghdl 0.29-0.31

--

-- Revision History: 

-- Date         Rev Version  Comment

-- 2013-10-05   537   1.0    Initial version (derived from s7_cmt_sfs)

------------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

library unisim;

use unisim.vcomponents.ALL;

use work.slvtypes.all;

entity s6_cmt_sfs is                    -- Spartan-6 CMT for simple freq. synth.

  generic (

    VCO_DIVIDE : positive := 1;         -- vco clock divide

    VCO_MULTIPLY : positive := 1;       -- vco clock multiply 

    OUT_DIVIDE : positive := 1;         -- output divide

    CLKIN_PERIOD : real := 10.0;        -- CLKIN period (def is 10.0 ns)

    CLKIN_JITTER : real := 0.01;        -- CLKIN jitter (def is 10 ps)

    STARTUP_WAIT : boolean := false;    -- hold FPGA startup till LOCKED

    GEN_TYPE : string := "PLL");        -- PLL or DCM

  port (

    CLKIN : in slbit;                   -- clock input

    CLKFX : out slbit;                  -- clock output (synthesized freq.) 

    LOCKED : out slbit                  -- pll/dcm locked

  );

end s6_cmt_sfs;

architecture syn of s6_cmt_sfs is

begin

  assert GEN_TYPE = "PLL" or GEN_TYPE = "DCM"

    report "assert(GEN_TYPE='PLL' or GEN_TYPE='DCM')"

    severity failure;

  NOGEN: if VCO_DIVIDE=1 and VCO_MULTIPLY=1 and OUT_DIVIDE=1 generate

    CLKFX  <= CLKIN;

    LOCKED <= '1';

  end generate NOGEN;

  USEPLL: if GEN_TYPE = "PLL" and

             not(VCO_DIVIDE=1 and VCO_MULTIPLY=1 and OUT_DIVIDE=1) generate

    signal CLKFBOUT         : slbit;

    signal CLKOUT0          : slbit;

    signal CLKOUT1_UNUSED   : slbit;

    signal CLKOUT2_UNUSED   : slbit;

    signal CLKOUT3_UNUSED   : slbit;

    signal CLKOUT4_UNUSED   : slbit;

    signal CLKOUT5_UNUSED   : slbit;

  begin

    PLL : pll_base

      generic map (

        BANDWIDTH            => "OPTIMIZED",

        CLK_FEEDBACK         => "CLKFBOUT",

        COMPENSATION         => "INTERNAL",

        DIVCLK_DIVIDE        => VCO_DIVIDE,

        CLKFBOUT_MULT        => VCO_MULTIPLY,

        CLKFBOUT_PHASE       => 0.000,

        CLKOUT0_DIVIDE       => OUT_DIVIDE,

        CLKOUT0_PHASE        => 0.000,

        CLKOUT0_DUTY_CYCLE   => 0.500,

        CLKIN_PERIOD         => CLKIN_PERIOD,

        REF_JITTER           => CLKIN_JITTER)

      port map (

        CLKFBOUT            => CLKFBOUT,

        CLKOUT0             => CLKOUT0,

        CLKOUT1             => CLKOUT1_UNUSED,

        CLKOUT2             => CLKOUT2_UNUSED,

        CLKOUT3             => CLKOUT3_UNUSED,

        CLKOUT4             => CLKOUT4_UNUSED,

        CLKOUT5             => CLKOUT5_UNUSED,

        CLKFBIN             => CLKFBOUT,

        CLKIN               => CLKIN,

        LOCKED              => LOCKED,

        RST                 => '0'

      );

    BUFG_CLKOUT : bufg

      port map (

        I => CLKOUT0,

        O => CLKFX

      );

  end generate USEPLL;

  USEDCM: if GEN_TYPE = "DCM" and

             not(VCO_DIVIDE=1 and VCO_MULTIPLY=1 and OUT_DIVIDE=1)  generate

    signal CLKOUT0          : slbit;

  begin

    DCM : dcm_sp

      generic map (

        CLK_FEEDBACK       => "NONE",

        CLKFX_DIVIDE       => VCO_DIVIDE,

        CLKFX_MULTIPLY     => VCO_MULTIPLY,

        CLKIN_DIVIDE_BY_2  => false,

        CLKIN_PERIOD       => CLKIN_PERIOD,

        CLKOUT_PHASE_SHIFT => "NONE",

        DESKEW_ADJUST      => "SYSTEM_SYNCHRONOUS",

        DSS_MODE           => "NONE",

        STARTUP_WAIT       => STARTUP_WAIT)

      port map (

        CLKIN   => CLKIN,

        CLKFX   => CLKOUT0,

        LOCKED  => LOCKED

      );

    BUFG_CLKOUT : bufg

      port map (

        I => CLKOUT0,

        O => CLKFX

      );

  end generate USEDCM;

end syn;