pluto_hdl_adi/library/common/ad_dds_2.v

// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
//
// In this HDL repository, there are many different and unique modules, consisting
// of various HDL (Verilog or VHDL) components. The individual modules are
// developed independently, and may be accompanied by separate and unique license
// terms.
//
// The user should read each of these license terms, and understand the
// freedoms and responsibilities that he or she has by using this source/core.
//
// This core is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE.
//
// Redistribution and use of source or resulting binaries, with or without modification
// of this file, are permitted under one of the following two license terms:
//
//   1. The GNU General Public License version 2 as published by the
//      Free Software Foundation, which can be found in the top level directory
//      of this repository (LICENSE_GPL2), and also online at:
//      <https://www.gnu.org/licenses/old-licenses/gpl-2.0.html>
//
// OR
//
//   2. An ADI specific BSD license, which can be found in the top level directory
//      of this repository (LICENSE_ADIBSD), and also on-line at:
//      https://github.com/analogdevicesinc/hdl/blob/master/LICENSE_ADIBSD
//      This will allow to generate bit files and not release the source code,
//      as long as it attaches to an ADI device.
//
// ***************************************************************************
// ***************************************************************************

`timescale 1ns/100ps

module ad_dds_2 #(

  // Range = 8-24
  parameter   DDS_DW = 16,
  // Range = 8-24
  parameter   PHASE_DW = 16,
  // Set 1 for CORDIC or 2 for Polynomial
  parameter   DDS_TYPE = 1,
  // Range = 8-24
  parameter   CORDIC_DW = 16,
  // Range = 8-24 ( make sure CORDIC_PHASE_DW < CORDIC_DW)
  parameter   CORDIC_PHASE_DW = 16
) (

  // interface

  input                   clk,
  input                   dds_format,
  input   [PHASE_DW-1:0]  dds_phase_0,
  input   [        15:0]  dds_scale_0,
  input   [PHASE_DW-1:0]  dds_phase_1,
  input   [        15:0]  dds_scale_1,
  output  [  DDS_DW-1:0]  dds_data
);

  // Local parameters

  localparam CORDIC = 1;
  localparam POLYNOMIAL = 2;

  // The width for Polynomial DDS is fixed (16)
  localparam DDS_D_DW = (DDS_TYPE == CORDIC) ? CORDIC_DW : 16;
  localparam DDS_P_DW = (DDS_TYPE == CORDIC) ? CORDIC_PHASE_DW : 16;
  // concatenation or truncation width
  localparam C_T_WIDTH = (DDS_D_DW > DDS_DW) ? (DDS_D_DW - DDS_DW) : (DDS_DW - DDS_D_DW);

  // internal registers

  reg     [  DDS_DW-1:0]  dds_data_width = 0;
  reg     [DDS_D_DW-1:0]  dds_data_rownd = 0;
  reg     [DDS_D_DW-1:0]  dds_data_int = 0;
  reg     [        15:0]  dds_scale_0_d = 0;
  reg     [        15:0]  dds_scale_1_d = 0;
  reg     [  DDS_DW-1:0]  dds_data_out = 0;

  // internal signals

  wire    [DDS_D_DW-1:0]  dds_data_0_s;
  wire    [DDS_D_DW-1:0]  dds_data_1_s;
  wire    [DDS_P_DW-1:0]  dds_phase_0_s;
  wire    [DDS_P_DW-1:0]  dds_phase_1_s;

  generate
    // dds channel output
    assign dds_data = dds_data_out;

    // output data format
    always @(posedge clk) begin
      dds_data_out[DDS_DW-1] <= dds_data_width[DDS_DW-1] ^ dds_format;
      dds_data_out[DDS_DW-2: 0] <= dds_data_width[DDS_DW-2: 0];
    end

    // set desired data width
    always @(posedge clk) begin
      if (DDS_DW < DDS_D_DW) begin // truncation
        // fair rownding
        dds_data_rownd <= dds_data_int + {(C_T_WIDTH){dds_data_int[DDS_D_DW-1]}};
        dds_data_width <= dds_data_rownd[DDS_D_DW-1:DDS_D_DW-DDS_DW];
      end else begin // concatenation
        dds_data_width <= dds_data_int << C_T_WIDTH;
      end
    end

    // dual tone
    always @(posedge clk) begin
      dds_data_int <= dds_data_0_s + dds_data_1_s;
    end

    always @(posedge clk) begin
      dds_scale_0_d <= dds_scale_0;
      dds_scale_1_d <= dds_scale_1;
    end

    // phase
    if (DDS_P_DW > PHASE_DW) begin
      assign dds_phase_0_s = {dds_phase_0,{DDS_P_DW-PHASE_DW{1'b0}}};
      assign dds_phase_1_s = {dds_phase_1,{DDS_P_DW-PHASE_DW{1'b0}}};
    end else begin
      assign dds_phase_0_s = dds_phase_0[(PHASE_DW-1):PHASE_DW-DDS_P_DW];
      assign dds_phase_1_s = dds_phase_1[(PHASE_DW-1):PHASE_DW-DDS_P_DW];
    end

    // dds-1

    ad_dds_1 #(
      .DDS_TYPE(DDS_TYPE),
      .DDS_D_DW(DDS_D_DW),
      .DDS_P_DW(DDS_P_DW)
    ) i_dds_1_0 (
      .clk (clk),
      .angle (dds_phase_0_s),
      .scale (dds_scale_0_d),
      .dds_data (dds_data_0_s));

    // dds-2

    ad_dds_1 #(
      .DDS_TYPE(DDS_TYPE),
      .DDS_D_DW(DDS_D_DW),
      .DDS_P_DW(DDS_P_DW)
    ) i_dds_1_1 (
      .clk (clk),
      .angle (dds_phase_1_s),
      .scale (dds_scale_1_d),
      .dds_data (dds_data_1_s));
  endgenerate

endmodule