CrossDomainSyncGen.vhd
68 lines
| 2.1 KiB
| text/x-vhdl
|
VhdlLexer
| r223 | ------------------------------------------------------------------------------ | |||
| -- This file is a part of the LPP VHDL IP LIBRARY | ||||
| -- Copyright (C) 2009 - 2013, Laboratory of Plasmas Physic - CNRS | ||||
| -- | ||||
| -- This program is free software; you can redistribute it and/or modify | ||||
| -- it under the terms of the GNU General Public License as published by | ||||
| -- the Free Software Foundation; either version 3 of the License, 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 more details. | ||||
| -- | ||||
| -- You should have received a copy of the GNU General Public License | ||||
| -- along with this program; if not, write to the Free Software | ||||
| -- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | ||||
| ------------------------------------------------------------------------------ | ||||
| -- Author : Alexis Jeandet | ||||
| -- Mail : alexis.jeandet@member.fsf.org | ||||
| ------------------------------------------------------------------------------ | ||||
| -- | ||||
| -- This module implements the SyncSignal generator explained in: | ||||
| -- Data Transfer between Asynchronous Clock Domains without Pain | ||||
| -- from Markus Schutti, Markus Pfaff, Richard Hagelauer | ||||
| -- http://www-micrel.deis.unibo.it/~benini/files/SNUG/paper9_final.pdf | ||||
| -- see page 4 | ||||
| -- | ||||
| -- | ||||
| library IEEE; | ||||
| use IEEE.STD_LOGIC_1164.ALL; | ||||
| entity CrossDomainSyncGen is | ||||
| Port ( | ||||
| reset : in STD_LOGIC; | ||||
| ClockS : in STD_LOGIC; | ||||
| ClockF : in STD_LOGIC; | ||||
| SyncSignal : out STD_LOGIC | ||||
| ); | ||||
| end CrossDomainSyncGen; | ||||
| architecture AR_CrossDomainSyncGen of CrossDomainSyncGen is | ||||
| signal FFSYNC : std_logic_vector(2 downto 0); | ||||
| begin | ||||
| SyncSignal <= FFSYNC(2); | ||||
| process(reset,ClockF) | ||||
| begin | ||||
| if reset = '0' then | ||||
| FFSYNC <= (others => '0'); | ||||
| elsif ClockF'event and ClockF = '1' then | ||||
| FFSYNC(0) <= ClockS; | ||||
| FFSYNC(1) <= FFSYNC(0); | ||||
| FFSYNC(2) <= FFSYNC(1); | ||||
| end if; | ||||
| end process; | ||||
| end AR_CrossDomainSyncGen; | ||||
