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wfjm.w11/rtl/vlib/simlib/simclk.vhd
Walter F.J. Mueller cbd8ce3468 - interim release w11a_V0.56 (untagged)
- re-organized handling of board and derived clocks in test benches
- added message filter definitions for some designs (.mfset files)
- added Cypress EZ-USB FX2 controller (USB interface)
- added firmware for EZ-USB FX2 supporting jtag access and data transfer
- FPGA configure over USB now supported directly in make build flow
- added test systems for USB testing and rlink over USB verification
- no functional change of w11a CPU core or any pre-existing test systems
- Note: Carefully read the disclaimer about usage of USB VID/PID numbers
        in the file README_USB-VID-PID.txt. You'll be responsible for any
        misuse of the defaults provided with the project sources !!
2013-01-02 21:06:53 +00:00

74 lines
2.3 KiB
VHDL

-- $Id: simclk.vhd 444 2011-12-25 10:04:58Z mueller $
--
-- Copyright 2007-2011 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: simclk - sim
-- Description: Clock generator for test benches
--
-- Dependencies: -
-- Test bench: -
-- Target Devices: generic
-- Tool versions: xst 8.2, 9.1, 9.2, 13.1; ghdl 0.18-0.29
--
-- Revision History:
-- Date Rev Version Comment
-- 2011-12-23 444 2.0 remove CLK_CYCLE output port
-- 2011-11-18 427 1.0.3 now numeric_std clean
-- 2008-03-24 129 1.0.2 CLK_CYCLE now 31 bits
-- 2007-10-12 88 1.0.1 avoid ieee.std_logic_unsigned, use cast to unsigned
-- 2007-08-10 72 1.0 Initial version
------------------------------------------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
use work.slvtypes.all;
entity simclk is -- test bench clock generator
generic (
PERIOD : time := 20 ns; -- clock period
OFFSET : time := 200 ns); -- clock offset (first up transition)
port (
CLK : out slbit; -- clock
CLK_STOP : in slbit -- clock stop trigger
);
end entity simclk;
architecture sim of simclk is
begin
proc_clk: process
constant clock_halfperiod : time := PERIOD/2;
begin
CLK <= '0';
wait for OFFSET;
clk_loop: loop
CLK <= '1';
wait for clock_halfperiod;
CLK <= '0';
wait for PERIOD-clock_halfperiod;
exit clk_loop when CLK_STOP = '1';
end loop;
CLK <= '1'; -- final clock cycle for clk_sim
wait for clock_halfperiod;
CLK <= '0';
wait for PERIOD-clock_halfperiod;
wait; -- endless wait, simulator will stop
end process proc_clk;
end sim;