写一个流水灯 FPGA Verilog程序

Sure! Here's an example of a Verilog code for a simple 4-bit LED sequence on an FPGA:

module led_sequence (
  input wire clk,
  output wire [3:0] led
);

reg [3:0] counter = 4'b0000;
reg [3:0] pattern = 4'b0001;

always @(posedge clk) begin
  counter <= counter + 1;
  
  case (counter)
    4'd0: pattern <= 4'b0001;
    4'd1: pattern <= 4'b0010;
    4'd2: pattern <= 4'b0100;
    4'd3: pattern <= 4'b1000;
    default: pattern <= 4'b0001;
  endcase
end

assign led = pattern;

endmodule

In this code, we have a 4-bit counter that increments on every positive edge of the clock signal. Based on the value of the counter, we assign a specific pattern to the `led` output. The LED sequence starts with `0001`, then shifts to `0010`, `0100`, and finally `1000`. After reaching `1000`, it loops back to `0001` again.

Please note that this is a basic example, and you might need to adjust it based on your specific FPGA board and requirements.