pluto_hdl_adi/library/axi_ad7616/axi_ad7616_pif.v

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// ***************************************************************************
// ***************************************************************************
// 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
2018-03-14 14:45:47 +00:00
// 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 axi_ad7616_pif #(
parameter UP_ADDRESS_WIDTH = 14) (
// physical interface
output cs_n,
output [15:0] db_o,
input [15:0] db_i,
output db_t,
output rd_n,
output wr_n,
// FIFO interface
output [15:0] adc_data,
output adc_valid,
output reg adc_sync,
// end of convertion
input end_of_conv,
input [ 4:0] burst_length,
// register access
input clk,
input rstn,
input rd_req,
input wr_req,
input [15:0] wr_data,
output reg [15:0] rd_data,
output reg rd_valid);
// state registers
localparam [ 2:0] IDLE = 3'h0,
CS_LOW = 3'h1,
CNTRL0_LOW = 3'h2,
CNTRL0_HIGH = 3'h3,
CNTRL1_LOW = 3'h4,
CNTRL1_HIGH = 3'h5,
CS_HIGH = 3'h6;
// internal registers
reg [ 2:0] transfer_state = 3'h0;
reg [ 2:0] transfer_state_next = 3'h0;
reg [ 1:0] width_counter = 2'h0;
reg [ 4:0] burst_counter = 5'h0;
reg wr_req_d = 1'h0;
reg rd_req_d = 1'h0;
reg rd_conv_d = 1'h0;
reg xfer_req_d = 1'h0;
reg rd_valid_d = 1'h0;
// internal wires
wire start_transfer_s;
wire rd_valid_s;
// FSM state register
always @(posedge clk) begin
if (rstn == 1'b0) begin
transfer_state <= 3'h0;
end else begin
transfer_state <= transfer_state_next;
end
end
// counters to control the RD_N and WR_N lines
assign start_transfer_s = end_of_conv | rd_req | wr_req;
always @(posedge clk) begin
if (rstn == 1'b0) begin
width_counter <= 2'h0;
end else begin
if((transfer_state == CNTRL0_LOW) || (transfer_state == CNTRL0_HIGH) ||
(transfer_state == CNTRL1_LOW) || (transfer_state == CNTRL1_HIGH))
width_counter <= width_counter + 1;
else
width_counter <= 2'h0;
end
end
always @(posedge clk) begin
if (rstn == 1'b0) begin
burst_counter <= 2'h0;
end else begin
if (transfer_state == CS_HIGH)
burst_counter <= burst_counter + 1;
else if (transfer_state == IDLE)
burst_counter <= 5'h0;
end
end
always @(negedge clk) begin
if (transfer_state == IDLE) begin
wr_req_d <= wr_req;
rd_req_d <= rd_req;
rd_conv_d <= end_of_conv;
end
end
// FSM next state logic
always @(*) begin
case (transfer_state)
IDLE : begin
transfer_state_next <= (start_transfer_s == 1'b1) ? CS_LOW : IDLE;
end
CS_LOW : begin
transfer_state_next <= CNTRL0_LOW;
end
CNTRL0_LOW : begin
transfer_state_next <= (width_counter != 2'b11) ? CNTRL0_LOW : CNTRL0_HIGH;
end
CNTRL0_HIGH : begin
transfer_state_next <= (width_counter != 2'b11) ? CNTRL0_HIGH :
((wr_req_d == 1'b1) || (rd_req_d == 1'b1)) ? CS_HIGH : CNTRL1_LOW;
end
CNTRL1_LOW : begin
transfer_state_next <= (width_counter != 2'b11) ? CNTRL1_LOW : CNTRL1_HIGH;
end
CNTRL1_HIGH : begin
transfer_state_next <= (width_counter != 2'b11) ? CNTRL1_HIGH : CS_HIGH;
end
CS_HIGH : begin
transfer_state_next <= (burst_length == burst_counter) ? IDLE : CNTRL0_LOW;
end
default : begin
transfer_state_next <= IDLE;
end
endcase
end
// data valid for the register access and m_axis interface
assign rd_valid_s = (((transfer_state == CNTRL0_HIGH) || (transfer_state == CNTRL1_HIGH)) &&
((rd_req_d == 1'b1) || (rd_conv_d == 1'b1))) ? 1'b1 : 1'b0;
// FSM output logic
assign db_o = wr_data;
always @(posedge clk) begin
rd_data <= (rd_valid_s & ~rd_valid_d) ? db_i : rd_data;
rd_valid_d <= rd_valid_s;
rd_valid <= rd_valid_s & ~rd_valid_d;
end
assign adc_valid = rd_valid;
assign adc_data = rd_data;
assign cs_n = (transfer_state == IDLE) ? 1'b1 : 1'b0;
assign db_t = ~wr_req_d;
assign rd_n = (((transfer_state == CNTRL0_LOW) && ((rd_conv_d == 1'b1) || rd_req_d == 1'b1)) ||
(transfer_state == CNTRL1_LOW)) ? 1'b0 : 1'b1;
assign wr_n = ((transfer_state == CNTRL0_LOW) && (wr_req_d == 1'b1)) ? 1'b0 : 1'b1;
// sync will be asserted at the first valid data right after the convertion start
always @(posedge clk) begin
if (end_of_conv == 1'b1) begin
adc_sync <= 1'b1;
end else if (rd_valid == 1'b1) begin
adc_sync <= 1'b0;
end
end
endmodule