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////////////////////////////////////////////////////////////////////////////////

//

// Filename:    xoddr.v

//

// Project:     CMod S6 System on a Chip, ZipCPU demonstration project

//

// Purpose:     When outputting a clock, Xilinx recommends using the ODDR

//              primitive to insure the clock's stability.  This is a simple

//      wrapper around that primitive, although it does cost one delay.

//      For the QSPI, this helps to make certain that as much of the logic

//      delay as possible has been removed from the path--to get the full

//      80MHz speed of our clock.  (The QSPI device on the S6 can run at 108MHz,

//      here, we will run it at 80MHz.)

//

// Creator:     Dan Gisselquist, Ph.D.

//              Gisselquist Technology, LLC

//

////////////////////////////////////////////////////////////////////////////////

//

// Copyright (C) 2015-2017, Gisselquist Technology, LLC

//

// This program is free software (firmware): you can redistribute it and/or

// modify it under the terms of  the GNU General Public License as published

// by the Free Software Foundation, either version 3 of the License, or (at

// your option) any later version.

//

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with this program.  (It's in the $(ROOT)/doc directory.  Run make with no

// target there if the PDF file isn't present.)  If not, see

// <http://www.gnu.org/licenses/> for a copy.

//

// License:     GPL, v3, as defined and found on www.gnu.org,

//              http://www.gnu.org/licenses/gpl.html

//

//

////////////////////////////////////////////////////////////////////////////////

//

//

module  xoddr(i_clk, i_v, o_pin);

        input   [1:0]    i_clk;

        input   [1:0]    i_v;

        output          o_pin;

        wire    w_internal;

        reg     last;

        ODDR2 #(

                .DDR_ALIGNMENT("C0"),

                .INIT(1'b1),

                .SRTYPE("ASYNC")

        ) ODDRi(

                .Q(o_pin),

                .CE(1'b1),

                .C0(i_clk[0]),

                .D0(i_v[0]),     // Negative clock edge (goes first)

                .C1(i_clk[1]),

                .D1(i_v[1]),    // Positive clock edge

                .R(1'b0),

                .S(1'b0));

endmodule