private void notify_Clicked(object sender, EventArgs e)
 {
     if (SelectCharacteristic != null)
     {
         if (notify_btn.Text.ToLower() == "notify")
         {
             isnotify        = true;
             notify_btn.Text = "Stop Notify";
             SelectCharacteristic.NotifyEvent += SelectCharacteristic_NotifyEvent;
             SelectCharacteristic.Notify();
         }
         else
         {
             isnotify        = false;
             notify_btn.Text = "Notify";
             SelectCharacteristic.StopNotify();
             SelectCharacteristic.NotifyEvent -= SelectCharacteristic_NotifyEvent;
         }
     }
 }