pluto_hdl_adi/projects/m2k/common/m2k_spi.v

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// ***************************************************************************
// ***************************************************************************
// Copyright 2014 - 2017 (c) Analog Devices, Inc. All rights reserved.
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//
// 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.
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//
// 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):
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//
// 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
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//
// ***************************************************************************
// ***************************************************************************
`timescale 1ns/100ps
module m2k_spi (
// 4-wire
input ad9963_csn,
input adf4360_cs,
input spi_clk,
input spi_mosi,
output spi_miso,
// 3-wire
inout spi_sdio);
// internal registers
reg [ 5:0] spi_count = 'd0;
reg spi_rd_wr_n = 'd0;
reg spi_enable = 'd0;
// check on rising edge and change on falling edge
always @(posedge spi_clk or posedge ad9963_csn) begin
if (ad9963_csn == 1'b1) begin
spi_count <= 6'd0;
spi_rd_wr_n <= 1'd0;
end else begin
spi_count <= spi_count + 1'b1;
if (spi_count == 6'd0) begin
spi_rd_wr_n <= spi_mosi;
end
end
end
always @(negedge spi_clk or posedge ad9963_csn) begin
if (ad9963_csn == 1'b1) begin
spi_enable <= 1'b0;
end else begin
if ((spi_count == 6'd16) && (ad9963_csn == 1'b0)) begin
spi_enable <= spi_rd_wr_n;
end
end
end
// io buffers
assign spi_miso = spi_sdio;
assign spi_sdio = (spi_enable == 1'b1) ? 1'bz : spi_mosi;
endmodule
// ***************************************************************************
// ***************************************************************************