Subversion Repositories openmsp430

//----------------------------------------------------------------------------

// Copyright (C) 2009 , Olivier Girard

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions

// are met:

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * 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.

//     * Neither the name of the authors nor the names of its contributors

//       may be used to endorse or promote products derived from this software

//       without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

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// OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

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//

//----------------------------------------------------------------------------

//

// *File Name: omsp_sync_cell.v

// 

// *Module Description:

//                       Generic synchronizer for the openMSP430

//

// *Author(s):

//              - Olivier Girard,    olgirard@gmail.com

//

//----------------------------------------------------------------------------

// $Rev: 103 $

// $LastChangedBy: olivier.girard $

// $LastChangedDate: 2011-03-05 15:44:48 +0100 (Sat, 05 Mar 2011) $

//----------------------------------------------------------------------------

module  omsp_sync_cell (

// OUTPUTs

    data_out,                      // Synchronized data output

// INPUTs

    clk,                           // Receiving clock

    data_in,                       // Asynchronous data input

    rst                            // Receiving reset (active high)

);

// OUTPUTs

//=========

output              data_out;      // Synchronized data output

// INPUTs

//=========

input               clk;          // Receiving clock

input               data_in;      // Asynchronous data input

input               rst;          // Receiving reset (active high)

//=============================================================================

// 1)  SYNCHRONIZER

//=============================================================================

reg  [1:0] data_sync;

always @(posedge clk or posedge rst)

  if (rst) data_sync <=  2'b00;

  else     data_sync <=  {data_sync[0], data_in};

assign     data_out   =   data_sync[1];

endmodule // omsp_sync_cell