pluto_hdl_adi/library/common/ad_edge_detect.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2013(c) Analog Devices, Inc.
//
// 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 Analog Devices, Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
// - The use of this software may or may not infringe the patent rights
// of one or more patent holders. This license does not release you
// from the requirement that you obtain separate licenses from these
// patent holders to use this software.
// - Use of the software either in source or binary form, must be run
// on or directly connected to an Analog Devices Inc. component.
//
// THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED.
//
// IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY
// RIGHTS, 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.
// ***************************************************************************
// ***************************************************************************
// ***************************************************************************
// ***************************************************************************
// A simple edge detector circuit
`timescale 1ns/100ps
module ad_edge_detect #(
parameter EDGE = 0) (
input clk,
input rst,
input in,
output reg out);
localparam POS_EDGE = 0;
localparam NEG_EDGE = 1;
localparam ANY_EDGE = 2;
reg ff_m1 = 0;
reg ff_m2 = 0;
always @(posedge clk) begin
if (rst == 1) begin
ff_m1 <= 0;
ff_m2 <= 0;
end else begin
ff_m1 <= in;
ff_m2 <= ff_m1;
end
end
always @(posedge clk) begin
if (rst == 1) begin
out <= 1'b0;
end else begin
if (EDGE == POS_EDGE) begin
out <= ff_m1 & ~ff_m2;
end else if (EDGE == NEG_EDGE) begin
out <= ~ff_m1 & ff_m2;
end else begin
out <= ff_m1 ^ ff_m2;
end
end
end
endmodule