pluto_hdl_adi/library/common/ad_dds.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2018 (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
// single channel dds (dual tone)
module ad_dds #(
parameter DISABLE = 0,
// range 8-24
parameter DDS_DW = 16,
// range 8-16 (FIX ME)
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,
// the clock radtio between the device clock(sample rate) and the dac_core clock
// 2^N, 1<N<6
parameter CLK_RATIO = 1) (
// interface
input clk,
input dac_dds_format,
input dac_data_sync,
input dac_valid,
input [ 15:0] tone_1_scale,
input [ 15:0] tone_2_scale,
input [ 15:0] tone_1_init_offset,
input [ 15:0] tone_2_init_offset,
input [ PHASE_DW-1:0] tone_1_freq_word,
input [ PHASE_DW-1:0] tone_2_freq_word,
output reg [DDS_DW*CLK_RATIO-1:0] dac_dds_data
);
wire [DDS_DW*CLK_RATIO-1:0] dac_dds_data_s;
reg dac_data_sync_m = 1'd0;
always @(posedge clk) begin
dac_dds_data <= dac_dds_data_s;
end
genvar i;
generate
if (DISABLE == 1) begin
assign dac_dds_data_s = {(DDS_DW*CLK_RATIO-1){1'b0}};
end else begin
// enable dds
reg [PHASE_DW-1:0] dac_dds_phase_0[1:CLK_RATIO];
reg [PHASE_DW-1:0] dac_dds_phase_1[1:CLK_RATIO];
reg [PHASE_DW-1:0] dac_dds_phase_0_m[1:CLK_RATIO];
reg [PHASE_DW-1:0] dac_dds_phase_1_m[1:CLK_RATIO];
reg [PHASE_DW-1:0] dac_dds_incr_0 = 'd0;
reg [PHASE_DW-1:0] dac_dds_incr_1 = 'd0;
reg [CLK_RATIO :1] sync_min_pulse_m = 'd0;
// For scenarios where the synchronization signal comes from an external
// source and it is high for a longer period of time, the phase
// accumulator stages must be reset, in order to avoid a noise like
// signal caused by sending all the summed outputs of each DDS stage.
// There is a minimum synchronization pulse width of n clock cycles,
// that is required to synchronize all phase accumulator stages.
// Where n is equal to the CLK_RATIO.
always @(posedge clk) begin
dac_data_sync_m <= dac_data_sync;
sync_min_pulse_m[1] <= dac_data_sync_m & !dac_data_sync |
sync_min_pulse_m[1] & !sync_min_pulse_m[CLK_RATIO];
end
for (i=1; i < CLK_RATIO; i=i+1) begin: sync_delay
always @(posedge clk) begin
sync_min_pulse_m[i+1] <= sync_min_pulse_m[i];
end
end
always @(posedge clk) begin
dac_dds_incr_0 <= tone_1_freq_word * CLK_RATIO;
dac_dds_incr_1 <= tone_2_freq_word * CLK_RATIO;
end
// phase accumulator
for (i=1; i <= CLK_RATIO; i=i+1) begin: dds_phase
always @(posedge clk) begin
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if (dac_data_sync == 1'b1) begin
dac_dds_phase_0[i] <= 'd0;
dac_dds_phase_1[i] <= 'd0;
end else if (sync_min_pulse_m[1] == 1'b1) begin
if (i == 1) begin
dac_dds_phase_0[1] <= tone_1_init_offset;
dac_dds_phase_1[1] <= tone_2_init_offset;
end else if (CLK_RATIO > 1)begin
dac_dds_phase_0[i] <= dac_dds_phase_0[i-1] + tone_1_freq_word;
dac_dds_phase_1[i] <= dac_dds_phase_1[i-1] + tone_2_freq_word;
end
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end else if (dac_valid == 1'b1) begin
dac_dds_phase_0[i] <= dac_dds_phase_0[i] + dac_dds_incr_0;
dac_dds_phase_1[i] <= dac_dds_phase_1[i] + dac_dds_incr_1;
end
if (dac_data_sync == 1'b1 || sync_min_pulse_m[1]) begin
dac_dds_phase_0_m[i] <= 'd0;
dac_dds_phase_1_m[i] <= 'd0;
end else begin
dac_dds_phase_0_m[i] <= dac_dds_phase_0[i];
dac_dds_phase_1_m[i] <= dac_dds_phase_1[i];
end
end
// phase to amplitude convertor
ad_dds_2 #(
.DDS_DW (DDS_DW),
.PHASE_DW (PHASE_DW),
.DDS_TYPE (DDS_TYPE),
.CORDIC_DW (CORDIC_DW),
.CORDIC_PHASE_DW (CORDIC_PHASE_DW))
i_dds_2 (
.clk (clk),
.dds_format (dac_dds_format),
.dds_phase_0 (dac_dds_phase_0_m[i]),
.dds_scale_0 (tone_1_scale),
.dds_phase_1 (dac_dds_phase_1_m[i]),
.dds_scale_1 (tone_2_scale),
.dds_data (dac_dds_data_s[(DDS_DW*i)-1:DDS_DW*(i-1)]));
end
end
endgenerate
endmodule