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riffa/fpga/riffa_hdl/cross_domain_signal.v

63 lines
2.8 KiB
Verilog

// ----------------------------------------------------------------------
// Copyright (c) 2015, The Regents of the University of California All
// rights reserved.
//
// 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 Regents of the University of California
// 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 REGENTS OF THE
// UNIVERSITY OF CALIFORNIA BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, 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 CONTRACT, STRICT LIABILITY, OR
// TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
// USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
// DAMAGE.
// ----------------------------------------------------------------------
//----------------------------------------------------------------------------
// Filename: cross_domain_signal.v
// Version: 1.00.a
// Verilog Standard: Verilog-2001
// Description: Send a signal from clock domain A into clock domain B
// and get the signal back into clock domain A. Domain A can know roughly when
// the signal is received domain B.
// Author: Matt Jacobsen
// History: @mattj: Version 2.0
//-----------------------------------------------------------------------------
`timescale 1ns/1ns
module cross_domain_signal (
input CLK_A, // Clock for domain A
input CLK_A_SEND, // Signal from domain A to domain B
output CLK_A_RECV, // Signal from domain B received in domain A
input CLK_B, // Clock for domain B
output CLK_B_RECV, // Signal from domain A received in domain B
input CLK_B_SEND // Signal from domain B to domain A
);
// Sync level signals across domains.
syncff sigAtoB (.CLK(CLK_B), .IN_ASYNC(CLK_A_SEND), .OUT_SYNC(CLK_B_RECV));
syncff sigBtoA (.CLK(CLK_A), .IN_ASYNC(CLK_B_SEND), .OUT_SYNC(CLK_A_RECV));
endmodule