programmazione Arduino e bluetooth

ciao ragazzi

ho provato di
allora ho caricato questo programma in arduino:

#include <SoftwareSerial.h>     //IDE >= 1.0
//#include <NewSoftSerial.h>    //IDE <= 0023

const int rxPin = 2;
const int txPin = 3;
const int ledPin = 13;
byte btval = 0;

SoftwareSerial bluetooth(rxPin, txPin);  //IDE >= 1.0
//NewSoftSerial bluetooth(rxPin, txPin);   //IDE <= 0023

void setup() {
  
  Serial.begin(9600);
  bluetooth.begin(9600);

  pinMode(ledPin,OUTPUT);
}

  
void loop() {

  if (bluetooth.available()) {  
    btval = bluetooth.read();
    if (btval == 1) {
       digitalWrite(ledPin, HIGH);
    } else {
        digitalWrite(ledPin, LOW);
    }
  }
}

poi ho scollegato il cavo di usb di arduino e ho alimentato esternamente , e dopo ho collegato la mia chiavetta bt sul pc, e poi ho aperto serialmonitor e ho iniziato digitare (1) per attivare il led, solo che mi da questo errori che ti ho scritto sotto, cosa sono???

javascript:void(0);

java.io.IOException: No error in nativeDrain
at gnu.io.RXTXPort.nativeDrain(Native Method)
at gnu.io.RXTXPort$SerialOutputStream.flush(RXTXPort.java:1201)
at processing.app.Serial.write(Serial.java:470)
at processing.app.Serial.write(Serial.java:492)
at processing.app.SerialMonitor.send(SerialMonitor.java:197)
at processing.app.SerialMonitor.access$100(SerialMonitor.java:31)
at processing.app.SerialMonitor$3.actionPerformed(SerialMonitor.java:86)
at javax.swing.JTextField.fireActionPerformed(JTextField.java:492)
at javax.swing.JTextField.postActionEvent(JTextField.java:705)
at javax.swing.JTextField$NotifyAction.actionPerformed(JTextField.java:820)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1636)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2851)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2886)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2814)
at java.awt.Component.processEvent(Component.java:6040)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4630)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:704)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:969)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:841)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:668)
at java.awt.Component.dispatchEventImpl(Component.java:4502)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Window.dispatchEventImpl(Window.java:2475)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
java.io.IOException: No error in nativeDrain
at gnu.io.RXTXPort.nativeDrain(Native Method)
at gnu.io.RXTXPort$SerialOutputStream.flush(RXTXPort.java:1201)
at processing.app.Serial.write(Serial.java:470)
at processing.app.Serial.write(Serial.java:492)
at processing.app.SerialMonitor.send(SerialMonitor.java:197)
at processing.app.SerialMonitor.access$100(SerialMonitor.java:31)
at processing.app.SerialMonitor$3.actionPerformed(SerialMonitor.java:86)
at javax.swing.JTextField.fireActionPerformed(JTextField.java:492)
at javax.swing.JTextField.postActionEvent(JTextField.java:705)
at javax.swing.JTextField$NotifyAction.actionPerformed(JTextField.java:820)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1636)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2851)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2886)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2814)
at java.awt.Component.processEvent(Component.java:6040)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4630)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1848)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:704)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:969)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:841)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:668)
at java.awt.Component.dispatchEventImpl(Component.java:4502)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Window.dispatchEventImpl(Window.java:2475)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)