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