pluto_hdl_adi/library/common/util_pulse_gen.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
// 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.
//
// Redistribution and use in source and binary forms,
// with or without modification of this file, are permitted under the terms of either
// (at the option of the user):
//
// 1. The GNU General Public License version 2 as published by the
// Free Software Foundation, which can be found in the top level directory, or at:
// https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html
//
// OR
//
// 2. An ADI specific BSD license as noted in the top level directory, or on-line at:
// https://github.com/analogdevicesinc/hdl/blob/dev/LICENSE
//
// ***************************************************************************
// ***************************************************************************
`timescale 1ns/1ps
module util_pulse_gen #(
parameter PULSE_WIDTH = 7,
parameter PULSE_PERIOD = 100000000)( // t_period * clk_freq
input clk,
input rstn,
input [31:0] pulse_period,
input pulse_period_en,
output reg pulse
);
// internal registers
reg [(PULSE_WIDTH-1):0] pulse_width_cnt = {PULSE_WIDTH{1'b1}};
reg [31:0] pulse_period_cnt = 32'h0;
reg [31:0] pulse_period_d = 32'b0;
wire end_of_period_s;
// flop the desired period
always @(posedge clk) begin
pulse_period_d <= (pulse_period_en) ? pulse_period : PULSE_PERIOD;
end
// a free running pulse generator
always @(posedge clk) begin
if (rstn == 1'b0) begin
pulse_period_cnt <= 32'h0;
end else begin
pulse_period_cnt <= (pulse_period_cnt < pulse_period_d) ? (pulse_period_cnt + 1) : 32'b0;
end
end
assign end_of_period_s = (pulse_period_cnt == (pulse_period_d - 1)) ? 1'b1 : 1'b0;
// generate pulse with a specified width
always @(posedge clk) begin
if (rstn == 1'b0) begin
pulse_width_cnt <= 0;
pulse <= 0;
end else begin
pulse_width_cnt <= (pulse == 1'b1) ? pulse_width_cnt + 1 : {PULSE_WIDTH{1'h0}};
if(end_of_period_s == 1'b1) begin
pulse <= 1'b1;
end else if(pulse_width_cnt == {PULSE_WIDTH{1'b1}}) begin
pulse <= 1'b0;
end
end
end
endmodule