Hardware Design: SIE

Hardware Design: SIE Git Source Tree

1	//==========================================
2	// Function : Code Gray counter.
3	// Coder : Alex Claros F.
4	// Date : 15/May/2005.
5	//=======================================
6
7	`timescale 1ns/1ps
8
9	module vgafb_graycounter
10	#(parameter COUNTER_WIDTH = 2)
11
12	(output reg [COUNTER_WIDTH-1:0] GrayCount_out, //'Gray' code count output.
13
14	input wire Enable_in, //Count enable.
15	input wire Clear_in, //Count reset.
16
17	input wire Clk);
18
19	/////////Internal connections & variables///////
20	reg [COUNTER_WIDTH-1:0] BinaryCount;
21
22	/////////Code///////////////////////
23
24	always @ (posedge Clk)
25	if (Clear_in) begin
26	BinaryCount <= {COUNTER_WIDTH{1'b 0}} + 1; //Gray count begins @ '1' with
27	GrayCount_out <= {COUNTER_WIDTH{1'b 0}}; // first 'Enable_in'.
28	end
29	else if (Enable_in) begin
30	BinaryCount <= BinaryCount + 1;
31	GrayCount_out <= {BinaryCount[COUNTER_WIDTH-1],
32	BinaryCount[COUNTER_WIDTH-2:0] ^ BinaryCount[COUNTER_WIDTH-1:1]};
33	end
34
35	endmodule
36

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