Verilog Code for Gray Counter

Gray code is one kind of binary number system where only one bit will change at a time. Today gray code is widely used in digital world. This will helpful for error correction and signal transmission. Gray counter is also useful in design and verification in VLSI domain. This code will generate gray code. Find out VHDL Code of Gray Counter here.

module gray_counter(clk, rst, out);
 input clk, rst;
 output reg [3:0] out;

 reg q0, q1, q2; 
 reg [3:0] count; 

 always @ (posedge clk)
 begin
  if (rst)
   count = 4'b0;
   out = 4'b0;
  else
   count = count + 1'b1;
   q2 = count[3] ^ count[2];
   q1 = count[2] ^ count[1];
   q0 = count[1] ^ count[0];
   out = {count[3], q2, q1, q0};
 end
endmodule