--- /dev/null
+//////////////////////////////////////////////////////////////////////
+//// ////
+//// eth_clockgen.v ////
+//// ////
+//// This file is part of the Ethernet IP core project ////
+//// http://www.opencores.org/projects/ethmac/ ////
+//// ////
+//// Author(s): ////
+//// - Igor Mohor (igorM@opencores.org) ////
+//// ////
+//// All additional information is avaliable in the Readme.txt ////
+//// file. ////
+//// ////
+//////////////////////////////////////////////////////////////////////
+//// ////
+//// Copyright (C) 2001 Authors ////
+//// ////
+//// This source file may be used and distributed without ////
+//// restriction provided that this copyright statement is not ////
+//// removed from the file and that any derivative work contains ////
+//// the original copyright notice and the associated disclaimer. ////
+//// ////
+//// This source file is free software; you can redistribute it ////
+//// and/or modify it under the terms of the GNU Lesser General ////
+//// Public License as published by the Free Software Foundation; ////
+//// either version 2.1 of the License, or (at your option) any ////
+//// later version. ////
+//// ////
+//// This source 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. See the GNU Lesser General Public License for more ////
+//// details. ////
+//// ////
+//// You should have received a copy of the GNU Lesser General ////
+//// Public License along with this source; if not, download it ////
+//// from http://www.opencores.org/lgpl.shtml ////
+//// ////
+//////////////////////////////////////////////////////////////////////
+//
+// CVS Revision History
+//
+// $Log: eth_clockgen.v,v $
+// Revision 1.1 2007-03-20 17:50:56 sithglan
+// add shit
+//
+// Revision 1.4 2005/02/21 12:48:05 igorm
+// Warning fixes.
+//
+// Revision 1.3 2002/01/23 10:28:16 mohor
+// Link in the header changed.
+//
+// Revision 1.2 2001/10/19 08:43:51 mohor
+// eth_timescale.v changed to timescale.v This is done because of the
+// simulation of the few cores in a one joined project.
+//
+// Revision 1.1 2001/08/06 14:44:29 mohor
+// A define FPGA added to select between Artisan RAM (for ASIC) and Block Ram (For Virtex).
+// Include files fixed to contain no path.
+// File names and module names changed ta have a eth_ prologue in the name.
+// File eth_timescale.v is used to define timescale
+// All pin names on the top module are changed to contain _I, _O or _OE at the end.
+// Bidirectional signal MDIO is changed to three signals (Mdc_O, Mdi_I, Mdo_O
+// and Mdo_OE. The bidirectional signal must be created on the top level. This
+// is done due to the ASIC tools.
+//
+// Revision 1.1 2001/07/30 21:23:42 mohor
+// Directory structure changed. Files checked and joind together.
+//
+// Revision 1.3 2001/06/01 22:28:55 mohor
+// This files (MIIM) are fully working. They were thoroughly tested. The testbench is not updated.
+//
+//
+
+`include "timescale.v"
+
+module eth_clockgen(Clk, Reset, Divider, MdcEn, MdcEn_n, Mdc);
+
+parameter Tp=1;
+
+input Clk; // Input clock (Host clock)
+input Reset; // Reset signal
+input [7:0] Divider; // Divider (input clock will be divided by the Divider[7:0])
+
+output Mdc; // Output clock
+output MdcEn; // Enable signal is asserted for one Clk period before Mdc rises.
+output MdcEn_n; // Enable signal is asserted for one Clk period before Mdc falls.
+
+reg Mdc;
+reg [7:0] Counter;
+
+wire CountEq0;
+wire [7:0] CounterPreset;
+wire [7:0] TempDivider;
+
+
+assign TempDivider[7:0] = (Divider[7:0]<2)? 8'h02 : Divider[7:0]; // If smaller than 2
+assign CounterPreset[7:0] = (TempDivider[7:0]>>1) - 1'b1; // We are counting half of period
+
+
+// Counter counts half period
+always @ (posedge Clk or posedge Reset)
+begin
+ if(Reset)
+ Counter[7:0] <= #Tp 8'h1;
+ else
+ begin
+ if(CountEq0)
+ begin
+ Counter[7:0] <= #Tp CounterPreset[7:0];
+ end
+ else
+ Counter[7:0] <= #Tp Counter - 8'h1;
+ end
+end
+
+
+// Mdc is asserted every other half period
+always @ (posedge Clk or posedge Reset)
+begin
+ if(Reset)
+ Mdc <= #Tp 1'b0;
+ else
+ begin
+ if(CountEq0)
+ Mdc <= #Tp ~Mdc;
+ end
+end
+
+
+assign CountEq0 = Counter == 8'h0;
+assign MdcEn = CountEq0 & ~Mdc;
+assign MdcEn_n = CountEq0 & Mdc;
+
+endmodule
+
+
projects / raggedstone / blobdiff