diff --git a/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/MicaZMote.java b/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/MicaZMote.java
index 0819b616e..21ed157ce 100644
--- a/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/MicaZMote.java
+++ b/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/MicaZMote.java
@@ -44,6 +44,7 @@ import org.contikios.cooja.MoteType;
 import org.contikios.cooja.Simulation;
 import org.contikios.cooja.mote.memory.MemoryInterface;
 import org.contikios.cooja.motes.AbstractEmulatedMote;
+
 import avrora.arch.avr.AVRProperties;
 import avrora.core.LoadableProgram;
 import avrora.sim.AtmelInterpreter;
@@ -54,6 +55,8 @@ import avrora.sim.mcu.EEPROM;
 import avrora.sim.platform.MicaZ;
 import avrora.sim.platform.PlatformFactory;
 
+import org.contikios.cooja.avrmote.interfaces.MicaClock;
+
 /**
  * @author Joakim Eriksson, Fredrik Osterlind
  */
@@ -74,6 +77,10 @@ public class MicaZMote extends AbstractEmulatedMote implements Mote {
 
   private EEPROM eeprom = null;
   
+  private long executed = 0;
+  private long skipped = 0;
+  
+  
   /* Stack monitoring variables */
   private boolean stopNextInstruction = false;
 
@@ -184,6 +191,10 @@ public class MicaZMote extends AbstractEmulatedMote implements Mote {
   private long cyclesExecuted = 0;
   private long cyclesUntil = 0;
   public void execute(long t) {
+    MicaClock clock = ((MicaClock) (myMoteInterfaceHandler.getClock()));
+    double deviation = clock.getDeviation();
+    long drift = clock.getDrift();
+    
     /* Wait until mote boots */
     if (myMoteInterfaceHandler.getClock().getTime() < 0) {
       scheduleNextWakeup(t - myMoteInterfaceHandler.getClock().getTime());
@@ -196,13 +207,22 @@ public class MicaZMote extends AbstractEmulatedMote implements Mote {
     } 
 
     /* TODO Poll mote interfaces? */
-
+    
+    /* skip if necessary */
+    if (((1-deviation) * executed) > skipped) {
+      skipped += 1;
+      scheduleNextWakeup(t + Simulation.MILLISECOND);
+    }
+    
     /* Execute one millisecond */
     cyclesUntil += NR_CYCLES_PER_MSEC;
     while (cyclesExecuted < cyclesUntil) {
       cyclesExecuted += interpreter.step();
     }
 
+     /* book keeping */
+    executed += 1;
+    
     /* TODO Poll mote interfaces? */
 
     /* Schedule wakeup every millisecond */
diff --git a/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/interfaces/MicaClock.java b/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/interfaces/MicaClock.java
index 468e07a73..569e08dfd 100644
--- a/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/interfaces/MicaClock.java
+++ b/tools/cooja/apps/avrora/src/org/contikios/cooja/avrmote/interfaces/MicaClock.java
@@ -54,10 +54,12 @@ public class MicaClock extends Clock {
   private MicaZMote myMote;
 
   private long timeDrift; /* Microseconds */
+  private double deviation;
   
   public MicaClock(Mote mote) {
     simulation = mote.getSimulation();
     myMote = (MicaZMote) mote;
+    deviation = 1.0;
   }
 
   public void setTime(long newTime) {
@@ -68,6 +70,15 @@ public class MicaClock extends Clock {
     return simulation.getSimulationTime() + timeDrift;
   }
 
+  public double getDeviation() {
+    return deviation;
+  }
+
+  public void setDeviation(double deviation) {
+    assert (deviation>0.0) && (deviation<=1.0);
+    this.deviation = deviation;
+  }
+
   public void setDrift(long drift) {
     timeDrift = drift;
   }
@@ -75,19 +86,4 @@ public class MicaClock extends Clock {
   public long getDrift() {
     return timeDrift;
   }
-
-  public JPanel getInterfaceVisualizer() {
-    return null;
-  }
-
-  public void releaseInterfaceVisualizer(JPanel panel) {
-  }
-
-  public Collection<Element> getConfigXML() {
-    return null;
-  }
-
-  public void setConfigXML(Collection<Element> configXML, boolean visAvailable) {
-  }
-
 }
diff --git a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/MspMote.java b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/MspMote.java
index 403376583..b22fbc145 100644
--- a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/MspMote.java
+++ b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/MspMote.java
@@ -78,6 +78,8 @@ import se.sics.mspsim.util.MapEntry;
 import se.sics.mspsim.util.MapTable;
 import se.sics.mspsim.profiler.SimpleProfiler;
 
+import org.contikios.cooja.mspmote.interfaces.MspClock;
+
 /**
  * @author Fredrik Osterlind
  */
@@ -288,13 +290,22 @@ public abstract class MspMote extends AbstractEmulatedMote implements Mote, Watc
 
   private long lastExecute = -1; /* Last time mote executed */
   private long nextExecute;
+  
+  private long executed = 0;
+  private long skipped = 0;
+  
   public void execute(long time) {
     execute(time, EXECUTE_DURATION_US);
   }
+
   public void execute(long t, int duration) {
+    MspClock clock = ((MspClock) (myMoteInterfaceHandler.getClock()));
+    double deviation = clock.getDeviation();
+    long drift = clock.getDrift();
+
     /* Wait until mote boots */
-    if (!booted && myMoteInterfaceHandler.getClock().getTime() < 0) {
-      scheduleNextWakeup(t - myMoteInterfaceHandler.getClock().getTime());
+    if (!booted && clock.getTime() < 0) {
+      scheduleNextWakeup(t - clock.getTime());
       return;
     }
     booted = true;
@@ -313,12 +324,17 @@ public abstract class MspMote extends AbstractEmulatedMote implements Mote, Watc
       throw new RuntimeException("Bad event ordering: " + lastExecute + " < " + t);
     }
 
+    if (((1-deviation) * executed) > skipped) {
+      lastExecute = lastExecute + duration; // (t+duration) - (t-lastExecute);
+      nextExecute = t+duration;
+      skipped += duration;
+      scheduleNextWakeup(nextExecute);
+    }
+    
     /* Execute MSPSim-based mote */
     /* TODO Try-catch overhead */
     try {
-      nextExecute =
-        t + duration +
-        myCpu.stepMicros(t - lastExecute, duration);
+      nextExecute = myCpu.stepMicros(Math.max(0, t-lastExecute), duration) + t + duration;
       lastExecute = t;
     } catch (EmulationException e) {
       String trace = e.getMessage() + "\n\n" + getStackTrace();
@@ -330,7 +346,9 @@ public abstract class MspMote extends AbstractEmulatedMote implements Mote, Watc
     if (nextExecute < t) {
       throw new RuntimeException(t + ": MSPSim requested early wakeup: " + nextExecute);
     }
+
     /*logger.debug(t + ": Schedule next wakeup at " + nextExecute);*/
+    executed += duration; 
     scheduleNextWakeup(nextExecute);
 
     if (stopNextInstruction) {
diff --git a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspClock.java b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspClock.java
index c66352e98..10aacffad 100644
--- a/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspClock.java
+++ b/tools/cooja/apps/mspsim/src/org/contikios/cooja/mspmote/interfaces/MspClock.java
@@ -52,9 +52,11 @@ public class MspClock extends Clock {
   private Simulation simulation;
   
   private long timeDrift; /* Microseconds */
+  private double deviation;
 
   public MspClock(Mote mote) {
     simulation = mote.getSimulation();
+    deviation = 1.0;
   }
 
   public void setTime(long newTime) {
@@ -72,20 +74,13 @@ public class MspClock extends Clock {
   public long getDrift() {
     return timeDrift;
   }
-
-  public JPanel getInterfaceVisualizer() {
-    /* TODO Show current CPU speed */
-    return null;
+  
+  public void setDeviation(double deviation) {
+    assert (deviation>0.0) && (deviation<=1.0);
+    this.deviation = deviation;
   }
 
-  public void releaseInterfaceVisualizer(JPanel panel) {
+  public double getDeviation() {
+    return deviation;
   }
-
-  public Collection<Element> getConfigXML() {
-    return null;
-  }
-
-  public void setConfigXML(Collection<Element> configXML, boolean visAvailable) {
-  }
-
 }
diff --git a/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiClock.java b/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiClock.java
index 127a7a3a7..b033ef06d 100644
--- a/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiClock.java
+++ b/tools/cooja/java/org/contikios/cooja/contikimote/interfaces/ContikiClock.java
@@ -114,6 +114,14 @@ public class ContikiClock extends Clock implements ContikiMoteInterface, PolledB
   public long getTime() {
     return moteTime;
   }
+  
+  public void setDeviation(double deviation) {
+    logger.fatal("Can't change deviation");;
+  }
+
+  public double getDeviation() {
+  	return 1.0;
+  }
 
   public void doActionsBeforeTick() {
     /* Update time */
@@ -161,5 +169,4 @@ public class ContikiClock extends Clock implements ContikiMoteInterface, PolledB
 
   public void setConfigXML(Collection<Element> configXML, boolean visAvailable) {
   }
-
 }
diff --git a/tools/cooja/java/org/contikios/cooja/interfaces/Clock.java b/tools/cooja/java/org/contikios/cooja/interfaces/Clock.java
index faefaddfc..58ec05fa5 100644
--- a/tools/cooja/java/org/contikios/cooja/interfaces/Clock.java
+++ b/tools/cooja/java/org/contikios/cooja/interfaces/Clock.java
@@ -30,7 +30,19 @@
 
 package org.contikios.cooja.interfaces;
 
+import java.awt.GridLayout;
+import java.awt.event.MouseAdapter;
+import java.awt.event.MouseEvent;
+import java.util.ArrayList;
+import java.util.Collection;
+
+import javax.swing.JButton;
+import javax.swing.JLabel;
+import javax.swing.JPanel;
+import javax.swing.JTextField;
+
 import org.contikios.cooja.*;
+import org.jdom.Element;
 
 /**
  * Represents a mote's internal clock. Notice that the overall
@@ -39,10 +51,10 @@ import org.contikios.cooja.*;
  * This observable never notifies.
  *
  * @author Fredrik Osterlind
+ *         Andreas Löscher
  */
 @ClassDescription("Clock")
 public abstract class Clock extends MoteInterface {
-
   /**
    * Set mote's time to given time.
    *
@@ -76,4 +88,88 @@ public abstract class Clock extends MoteInterface {
    */
   public abstract long getDrift();
 
+
+  /**
+   * The clock deviation is a factor that represents with how much speed the
+   * mote progresses through the simulation in relation to the simulation speed.
+   *
+   * A value of 1.0 results in the mote being simulated with the same speed
+   * as the simulation. A value of 0.5 results in the mote being simulation
+   * at half of the simulation speed.
+   *
+   *  @param deviation Deviation factor
+   */
+  public abstract void setDeviation(double deviation);
+
+  /**
+   * Get deviation factor
+   */
+  public abstract double getDeviation();
+  
+  @Override
+  public JPanel getInterfaceVisualizer() {
+    JPanel panel = new JPanel();
+    GridLayout layout = new GridLayout(0,2);
+    
+    /* elements */
+    final JLabel timeLabel = new JLabel("Time (ms)");
+    final JTextField timeField = new JTextField(String.valueOf(getTime() / 1000));
+    final JLabel deviationLabel = new JLabel("Deviation Factor");
+    final JTextField deviationField = new JTextField(String.valueOf(getDeviation()));
+    final JButton readButton = new JButton("Read Clock Values");
+    final JButton updateButton = new JButton("Write Clock Values");
+    /* set layout */
+    panel.setLayout(layout);
+    /* add components */
+    panel.add(timeLabel);
+    panel.add(timeField);
+    panel.add(deviationLabel);
+    panel.add(deviationField);
+    panel.add(readButton);
+    panel.add(updateButton);
+    
+    readButton.addMouseListener(new MouseAdapter() {      
+      @Override
+      public void mouseClicked(MouseEvent ev) {
+        if (ev.getButton()==1) {
+          timeField.setText(String.valueOf(getTime() / 1000));
+          deviationField.setText(String.valueOf(getDeviation()));
+        }
+      }
+    });
+    
+    updateButton.addMouseListener(new MouseAdapter() {      
+      @Override
+      public void mouseClicked(MouseEvent ev) {
+        if (ev.getButton()==1) {
+          setTime(Long.parseLong(timeField.getText()) * 1000);
+          setDeviation(Double.parseDouble(deviationField.getText()));
+        }
+      }
+    });
+    
+    return panel;
+  }
+  
+  @Override
+  public void releaseInterfaceVisualizer(JPanel panel) {
+  }
+ 
+  @Override
+  public Collection<Element> getConfigXML() {
+    ArrayList<Element> config = new ArrayList<Element>();
+    Element element = new Element("deviation");
+    element.setText(String.valueOf(getDeviation()));
+    config.add(element);
+    return config;
+  }
+
+  @Override
+  public void setConfigXML(Collection<Element> configXML, boolean visAvailable) {
+    for (Element element : configXML) {
+      if (element.getName().equals("deviation")) {
+        setDeviation(Double.parseDouble(element.getText()));
+      }
+    }
+  }
 }