trashernet/bench/pll0.vhd

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-- -------------------------------------------------------------------------- --
-- TRASHERNET - A Trashy Ethernet Stack for FPGAs --
-- -------------------------------------------------------------------------- --
-- pll0.vhd : Simulates the PLL component present in some demo designs
-- -------------------------------------------------------------------------- --
-- Author : Markus Koch <markus@notsyncing.net>
-- Contributors : None
-- License : Mozilla Public License (MPL) Version 2
-- -------------------------------------------------------------------------- --
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity pll0 is
port(
CLK : in std_logic;
CLKOP : out std_logic;
LOCK : out std_logic
);
end entity pll0;
architecture bench of pll0 is
begin
clock_driver : process
constant period : time := 7.1429 ns; -- 140 MHz configured clock
begin
CLKOP <= '0';
LOCK <= '0';
wait until CLK'event;
wait for 12 ns;
LOCK <= '1';
loop
CLKOP <= '0';
wait for period / 2;
CLKOP <= '1';
wait for period / 2;
end loop;
end process clock_driver;
end architecture bench;