pluto_hdl_adi/library/common/ad_edge_detect.v

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// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
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// Each core or library found in this collection may have its own licensing terms. 
// The user should keep this in in mind while exploring these cores. 
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// 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