module wokwi( output a,b,     // top level module must be named "wokwi"
    input CLK, x, y,          // declarations can be on one line
    output OUT,
    );

    servo_test tester(        // instantiate module
        .mclk  (CLK),
        .led   (a),
        .servo (OUT)
    );
    
endmodule

module servo_test (
   input  mclk,
   output led,
   output servo
   );
   
   reg [14:0] counter;
   reg        servo_reg;

   reg [10:0] control = 0;
   reg        toggle  = 1;


   always @(posedge mclk)
   begin

      // servo algorithm

      counter <= counter + 1;

      if (counter == 'd19999)    // count to 20 ms using 1 MHz clock
         counter <= 0;
         
//    if (counter < ('d1460         ))   // close to center in wokwi, may be different in real life
      if (counter < ('d460 + control))   //                    __________
         servo_reg <= 1;                 //  generate pulse __|          |_______
      else                               // that starts when counter == 0
         servo_reg <= 0;                 // and ends when counter == (control + 460)
         
      
      // test algorithm                  // this can be omitted
      if (control == 'd2000)             // sweep value of control between 0 and 2000
         toggle <= 0;
      if (control == 0)
         toggle <= 1;
      
      if (counter == 0)
      begin
         if (toggle == 0)
            control <= control - 10;
         else
            control <= control + 10;
      end

   end

   assign led   = toggle;                // outputs the value of toggle to the LED
   assign servo = servo_reg;             // output control signal to servo

endmodule