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[/] [vg_z80_sbc/] [trunk/] [rtl/] [gray_counter.v] - Rev 3
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//========================================== // Function : Code Gray counter. // Coder : Alex Claros F. // Date : 15/May/2005. //======================================= `timescale 1ns/1ps module GrayCounter #(parameter COUNTER_WIDTH = 2) (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
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