`timescale 1ns / 1ns module Top ( input sys_clk, input rst_n, output reg [3:0] led, output reg [3:0] key, output wire usb_serial_tx, input wire usb_serial_rx, output wire [35:3] test_io ); wire inclkpll_clk0out; inclkpll inclkpll_inst ( .clkin1 (sys_clk), .clkout0(inclkpll_clk0out) ); des_ttl_generator des_ttl_generator_inst ( .clk(sys_clk), .rst_n(rst_n), .addr(), .wr_data(0), .wr_en(0), .rd_data(), .signal_in(1), .ttloutput(test_io[3]) ); endmodule