Here’s an example Verilog code to implement a 4-bit gray code counter circuit:
module gray_counter (output reg [3:0] count, input clk);
always @(posedge clk) begin
count <= count ^ (count >> 1);
end
endmodule
This code defines a module called “gray_counter” that implements a 4-bit gray code counter. The output “count” is a registered output that represents the current state of the counter. The input “clk” is the clock input that controls the counter operation.
The “always @(posedge clk)” block is a sequential logic block that updates the “count” output based on the clock signal. On every positive edge of the clock, the counter updates the current state of “count” by performing an exclusive OR operation between “count” and “count” shifted right by one bit. This generates the next gray code number in the sequence.
Note that this Verilog code assumes that the “count” output and the “clk” input are both 1-bit signals. If you want to use multi-bit signals, you would need to modify the code accordingly. Additionally, this code implements a rising-edge triggered counter. If you wanted to implement a falling-edge triggered counter, you would need to modify the code accordingly.