module blinky ( input clki, output led0, output led1, output led2, output led3 ); //`include "ps7.vh" BUFGCTRL clk_gb ( .I0(clki), .CE0(1'b1), .CE1(1'b0), .S0(1'b1), .S1(1'b0), .IGNORE0(1'b0), .IGNORE1(1'b0), .O(clk) ); localparam BITS = 4; localparam LOG2DELAY = 23; reg [BITS+LOG2DELAY-1:0] counter = 0; reg [BITS-1:0] outcnt; always @(posedge clk) begin counter <= counter + 1; outcnt <= counter >> LOG2DELAY; end assign {led0, led1, led2, led3} = outcnt /*^ (outcnt >> 1)*/; endmodule