graycounter.v

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//==========================================// Function : Code Gray counter.// Coder : Alex Claros F.// Date : 15/May/2005.//=======================================

`timescale 1ns/1ps

module GrayCounter  #(parameter COUNTER_WIDTH = 4) 

(output reg [COUNTER_WIDTH-1:0] GrayCount_out, //'Gray' code count output. 

input wire Enable_in, //Count enable.  input wire Clear_in, //Count reset. 

input wire Clk);

  /////////Internal connections & variables///////  reg [COUNTER_WIDTH-1:0] BinaryCount;

  /////////Code/////////////////////// 

always @ (posedge Clk)  if (Clear_in) begin  BinaryCount <= {COUNTER_WIDTH{1'b 0}} + 1; //Gray count begins @'1' with  GrayCount_out <= {COUNTER_WIDTH{1'b 0}}; // first 'Enable_in'.  end  else if (Enable_in) begin  BinaryCount <= BinaryCount + 1;  GrayCount_out <= {BinaryCount[COUNTER_WIDTH-1],  BinaryCount[COUNTER_WIDTH-2:0] ^ BinaryCount[COUNTER_WIDTH-1:1]};  end 

endmodule