daqlink_7s_sync_block.vhd

--////////////////////////////////////////////////////////////////////////////////
--//   ____  ____ 
--//  /   /\/   / 
--// /___/  \  /    Vendor: Xilinx 
--// \   \   \/     Version : 2.7
--//  \   \         Application : 7 Series FPGAs Transceivers Wizard 
--//  /   /         Filename :daqlink_7s_sync_block.vhd
--// /___/   /\     
--// \   \  /  \ 
--//  \___\/\___\ 
--//
--//
--
-- Description: Used on signals crossing from one clock domain to
--              another, this is a flip-flop pair, with both flops
--              placed together with RLOCs into the same slice.  Thus
--              the routing delay between the two is minimum to safe-
--              guard against metastability issues.
--                     
--
-- Module DAQLINK_7S_sync_block
-- Generated by Xilinx 7 Series FPGAs Transceivers Wizard
-- 
-- 
-- (c) Copyright 2010-2012 Xilinx, Inc. All rights reserved.
-- 
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library ieee;
use ieee.std_logic_1164.all;

library unisim;
use unisim.vcomponents.all;

entity daqlink_7s_sync_block is
  generic (
    INITIALISE : bit_vector(1 downto 0) := "00"
  );
  port (
    clk         : in  std_logic;          -- clock to be sync'ed to
    data_in     : in  std_logic;          -- Data to be 'synced'
    data_out    : out std_logic           -- synced data
    );

end daqlink_7s_sync_block;


architecture structural of daqlink_7s_sync_block is


  -- Internal Signals
  signal data_sync1 : std_logic;

  -- These attributes will stop Vivado translating the desired flip-flops into an
  -- SRL based shift register.
  attribute ASYNC_REG                   : string;
  attribute ASYNC_REG of data_sync      : label is "TRUE";
  attribute ASYNC_REG of data_sync_reg  : label is "TRUE";

 -- These attributes will stop timing errors being reported on the target flip-flop during back annotated SDF simulation.
  attribute MSGON                      : string;
  attribute MSGON of data_sync         : label is "FALSE";
  attribute MSGON of data_sync_reg     : label is "FALSE";

  -- These attributes will stop XST translating the desired flip-flops into an
  -- SRL based shift register.
  attribute shreg_extract                   : string;
  attribute shreg_extract of data_sync      : label is "no";
  attribute shreg_extract of data_sync_reg  : label is "no";

  
begin

  data_sync : FD
  generic map (
    INIT  => INITIALISE(0)
  )
  port map (
    C     => clk,
    D     => data_in,
    Q     => data_sync1
  );


  data_sync_reg : FD
  generic map (
    INIT  => INITIALISE(1)
  )
  port map (
    C     => clk,
    D     => data_sync1,
    Q     => data_out
  );


end structural;