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//======================================================================
//
// novena_dcm_spartan6.v
// ---------------------
// Wrapper file for Xilinx-specific DCM_SP primitive and supporting
// vendor-specific stuff. This wrapper can be used to get rid of
// "Clocking Wizard" IP core and associated coregen pain.
//
//
// Author: Pavel Shatov
// Copyright (c) 2015, NORDUnet A/S All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// - Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// - Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
// be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
// IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
// TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
//======================================================================
`timescale 1ns / 1ps
module novena_dcm_spartan6
(
input wire clk_in_p,
input wire clk_in_n,
input wire reset_in,
output wire gclk_out,
output wire gclk_missing_out,
output wire clk_out,
output wire clk_valid_out
);
//
// Parameters
//
parameter CLK_OUT_MUL = 2; // multiply factor for output clock frequency (2..32)
parameter CLK_OUT_DIV = 2; // divide factor for output clock frequency (1..32)
//
// IBUFGDS
//
/* Xilinx-specific primitive to handle LVDS input signal. */
(* BUFFER_TYPE="NONE" *)
wire clk_in;
IBUFGDS IBUFGDS_gclk
(
.I(clk_in_p),
.IB(clk_in_n),
.O(clk_in)
);
//
// DCM_SP
//
/* Xilinx-specific primitive. */
wire dcm_clk_0; // primary (1:1) output
wire dcm_clk_feedback; // PLL feedback path
wire dcm_clk_fx; // synthesized frequency
wire dcm_locked_int; // locked flag
wire [ 7: 0] dcm_status_int; // status of DCM
DCM_SP #
(
.STARTUP_WAIT ("FALSE"),
.DESKEW_ADJUST ("SYSTEM_SYNCHRONOUS"),
.CLK_FEEDBACK ("1X"),
.PHASE_SHIFT (0),
.CLKOUT_PHASE_SHIFT ("NONE"),
.CLKIN_PERIOD (20.0), // 50 MHz => 20 ns
.CLKIN_DIVIDE_BY_2 ("FALSE"),
.CLKDV_DIVIDE (5.000),
.CLKFX_MULTIPLY (CLK_OUT_MUL),
.CLKFX_DIVIDE (CLK_OUT_DIV)
)
DCM_SP_inst
(
.RST (reset_in),
.CLKIN (gclk_out),
.CLKFB (dcm_clk_feedback),
.CLKDV (),
.CLK0 (dcm_clk_0),
.CLK90 (),
.CLK180 (),
.CLK270 (),
.CLK2X (),
.CLK2X180 (),
.CLKFX (dcm_clk_fx),
.CLKFX180 (),
.PSCLK (1'b0),
.PSEN (1'b0),
.PSINCDEC (1'b0),
.PSDONE (),
.LOCKED (dcm_locked_int),
.STATUS (dcm_status_int),
.DSSEN (1'b0)
);
//
// Mapping
//
assign gclk_out = clk_in;
assign gclk_missing_out = dcm_status_int[1];
assign clk_valid_out = dcm_locked_int & ((dcm_status_int[2:1] == 2'b00) ? 1'b1 : 1'b0);
//
// Feedback Path
//
/* DCM_SP requires BUFG primitive in its feedback path. */
BUFG BUFG_feedback
(
.I (dcm_clk_0),
.O (dcm_clk_feedback)
);
//
// Output Buffer
//
/* Connect system clock to global clocking network. */
BUFG BUFG_output
(
.I (dcm_clk_fx),
.O (clk_out)
);
endmodule
|
