pluto_hdl_adi/library/ad463x_data_capture/ad463x_data_capture.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2021 (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
// The AD4630-24 device requires this module to capture data in master and
// echo clock mode, because the data is clocked by the BUSY/SCLKOUT line,
// independent from the SPI interface
module ad463x_data_capture #(
parameter DDR_EN = 0,
parameter NUM_OF_LANES = 2,
parameter DATA_WIDTH = 32
) (
input clk, // core clock of the SPIE
input csn, // CSN (chip select)
input echo_sclk, // BUSY/SCLKOUT
input [NUM_OF_LANES-1:0] data_in, // serial data lines
output [(NUM_OF_LANES * DATA_WIDTH)-1:0] m_axis_data, // parallel data lines
output m_axis_valid, // data validation
input m_axis_ready // NOTE: back pressure is ignored
);
reg csn_d;
wire reset;
always @(posedge clk) begin
csn_d <= csn;
end
// negative edge resets the shift registers
assign reset = ~csn & csn_d;
// CSN positive edge validates the output data
// WARNING: there isn't any buffering for data, if the sink module is not
// ready, the data will be discarded
assign m_axis_valid = csn & ~csn_d & m_axis_ready;
genvar i, j;
generate
if (DDR_EN) // Double Data Rate mode
begin
for (i=0; i<NUM_OF_LANES; i=i+1) begin
reg [DATA_WIDTH-1:0] data_shift_p;
reg [DATA_WIDTH-1:0] data_shift_n;
// shift register for positive edge
always @(negedge echo_sclk or posedge reset) begin
if (reset) begin
data_shift_n <= 0;
end else begin
data_shift_n <= {data_shift_n, data_in[i]};
end
end
// shift register for positive edge
always @(posedge echo_sclk or posedge reset) begin
if (reset) begin
data_shift_p <= 0;
end else begin
data_shift_p <= {data_shift_p, data_in[i]};
end
end
// DDR output logic - only the first 16 bits are forwarded
for (j=0; j<DATA_WIDTH/2; j=j+1) begin
assign m_axis_data[DATA_WIDTH*i+(j*2)+:2] = {data_shift_p[j], data_shift_n[j]};
end
end /* for loop */
end else begin // Single Data Rate mode
for (i=0; i<NUM_OF_LANES; i=i+1) begin
reg [DATA_WIDTH-1:0] data_shift_n;
// shift register for positive edge
always @(negedge echo_sclk or posedge reset) begin
if (reset) begin
data_shift_n <= 0;
end else begin
data_shift_n <= {data_shift_n, data_in[i]};
end
end
// SDR output logic
assign m_axis_data[DATA_WIDTH*i+:DATA_WIDTH] = data_shift_n;
end /* for loop */
end
endgenerate
endmodule