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[/] [w11/] [tags/] [w11a_V0.7/] [rtl/] [vlib/] [xlib/] [dcm_sfs_gsim.vhd] - Rev 36
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-- $Id: dcm_sfs_gsim.vhd 649 2015-02-21 21:10:16Z mueller $ -- -- Copyright 2010-2011 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: dcm_sfs - sim -- Description: DCM for simple frequency synthesis -- simple vhdl model, without Xilinx UNISIM primitives -- -- Dependencies: - -- Test bench: - -- Target Devices: generic Spartan-3A,-3E -- Tool versions: xst 12.1-14.7; ghdl 0.29-0.31 -- -- Revision History: -- Date Rev Version Comment -- 2011-11-17 426 1.0.1 rename dcm_sp_sfs -> dcm_sfs -- 2010-11-12 338 1.0 Initial version ------------------------------------------------------------------------------ library ieee; use ieee.std_logic_1164.all; use work.slvtypes.all; entity dcm_sfs is -- DCM for simple frequency synthesis generic ( CLKFX_DIVIDE : positive := 1; -- FX clock divide (1-32) CLKFX_MULTIPLY : positive := 1; -- FX clock multiply (2-32) (1->no DCM) CLKIN_PERIOD : real := 20.0); -- CLKIN period (def is 20.0 ns) port ( CLKIN : in slbit; -- clock input CLKFX : out slbit; -- clock output (synthesized freq.) LOCKED : out slbit -- dcm locked ); end dcm_sfs; architecture sim of dcm_sfs is signal CLK_DIVPULSE : slbit := '0'; signal CLKOUT_PERIOD : time := 0 ns; signal R_CLKOUT : slbit := '0'; signal R_LOCKED : slbit := '0'; begin proc_clkin : process (CLKIN) variable t_lastclkin : time := 0 ns; variable t_lastperiod : time := 0 ns; variable t_period : time := 0 ns; variable nclkin : integer := 1; begin if CLKIN'event then if CLKIN = '1' then -- if CLKIN rising edge if t_lastclkin > 0 ns then t_lastperiod := t_period; t_period := now - t_lastclkin; CLKOUT_PERIOD <= (t_period * CLKFX_DIVIDE) / CLKFX_MULTIPLY; if t_lastperiod > 0 ns and abs(t_period-t_lastperiod) > 1 ps then report "dcm_sp_sfs: CLKIN unstable" severity warning; end if; end if; t_lastclkin := now; if t_period > 0 ns then nclkin := nclkin - 1; if nclkin <= 0 then nclkin := CLKFX_DIVIDE; CLK_DIVPULSE <= '1'; R_LOCKED <= '1'; end if; end if; else -- if CLKIN falling edge CLK_DIVPULSE <= '0'; end if; end if; end process proc_clkin; proc_clkout : process variable t_lastclkin : time := 0 ns; variable t_lastperiod : time := 0 ns; variable t_period : time := 0 ns; variable nclkin : integer := 1; begin loop wait until CLK_DIVPULSE = '1'; for i in 1 to CLKFX_MULTIPLY loop R_CLKOUT <= '1'; wait for CLKOUT_PERIOD/2; R_CLKOUT <= '0'; if i /= CLKFX_MULTIPLY then wait for CLKOUT_PERIOD/2; end if; end loop; -- i end loop; end process proc_clkout; CLKFX <= R_CLKOUT; LOCKED <= R_LOCKED; end sim;
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