diff -N ReadoutTimestamp.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ ReadoutTimestamp.java	20 Mar 2013 00:09:42 -0000	1.1
@@ -0,0 +1,107 @@

+package org.lcsim.hps.readout.ecal;
+
+import java.util.ArrayList;
+import java.util.List;
+import org.lcsim.event.EventHeader;
+import org.lcsim.event.GenericObject;
+import org.lcsim.hps.recon.tracking.SimpleSvtReadout;
+
+/**
+ *
+ * @author Sho Uemura <[log in to unmask]>
+ * @version $Id: ReadoutTimestamp.java,v 1.1 2013/03/20 00:09:42 meeg Exp $
+ */
+public class ReadoutTimestamp implements GenericObject {
+
+    public static final String collectionName = "ReadoutTimestamps";
+    public static final int SYSTEM_TRIGGER = 0;
+    public static final int SYSTEM_TRACKER = 1;
+    public static final int SYSTEM_ECAL = 2;
+    private int system;
+    private double time;
+
+    public ReadoutTimestamp(int system, double time) {
+        this.system = system;
+        this.time = time;
+    }
+
+    public static void addTimestamp(TriggerableDriver triggerable, EventHeader event) {
+        ReadoutTimestamp timestamp = null;
+        if (TriggerDriver.class.isInstance(triggerable)) {
+            timestamp = new ReadoutTimestamp(SYSTEM_TRIGGER, triggerable.readoutDeltaT());
+        } else if (SimpleSvtReadout.class.isInstance(triggerable)) {
+            timestamp = new ReadoutTimestamp(SYSTEM_TRACKER, triggerable.readoutDeltaT());
+        } else if (EcalReadoutDriver.class.isInstance(triggerable)) {
+            timestamp = new ReadoutTimestamp(SYSTEM_ECAL, triggerable.readoutDeltaT());
+        }
+        addTimestamp(timestamp, event);
+    }
+
+    public static void addTimestamp(ReadoutTimestamp timestamp, EventHeader event) {
+        List<ReadoutTimestamp> timestamps;
+        if (event.hasCollection(ReadoutTimestamp.class, collectionName)) {
+            timestamps = event.get(ReadoutTimestamp.class, collectionName);
+        } else {
+            timestamps = new ArrayList<ReadoutTimestamp>();
+            event.put(collectionName, timestamps, ReadoutTimestamp.class, 0);
+        }
+        timestamps.add(timestamp);
+    }
+
+    public static double getTimestamp(int system, EventHeader event) {
+        if (event.hasCollection(GenericObject.class, collectionName)) {
+            List<GenericObject> timestamps = event.get(GenericObject.class, collectionName);
+            for (GenericObject timestamp : timestamps) {
+                if (timestamp.getIntVal(0) == system) {
+                    return timestamp.getDoubleVal(0);
+                }
+            }
+            return 0;
+        } else {
+            return 0;
+        }
+    }
+
+    @Override
+    public int getNInt() {
+        return 1;
+    }
+
+    @Override
+    public int getNFloat() {
+        return 0;
+    }
+
+    @Override
+    public int getNDouble() {
+        return 1;
+    }
+
+    @Override
+    public int getIntVal(int index) {
+        if (index == 0) {
+            return system;
+        } else {
+            throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    @Override
+    public float getFloatVal(int index) {
+        throw new ArrayIndexOutOfBoundsException();
+    }
+
+    @Override
+    public double getDoubleVal(int index) {
+        if (index == 0) {
+            return time;
+        } else {
+            throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    @Override
+    public boolean isFixedSize() {
+        return true;
+    }
+}

diff -u -r1.2 -r1.3
--- TriggerDriver.java	19 Mar 2013 22:24:07 -0000	1.2
+++ TriggerDriver.java	20 Mar 2013 00:09:42 -0000	1.3
@@ -4,6 +4,7 @@

 import java.io.IOException;
 import java.io.PrintStream;
 import java.io.PrintWriter;

+import java.util.ArrayList;

 import java.util.List;
 
 

@@ -20,7 +21,7 @@

  * Applies SVT trigger latency and sends trigger signal to SVT
  *
  * @author Sho Uemura <[log in to unmask]>

- * @version $Id: TriggerDriver.java,v 1.2 2013/03/19 22:24:07 meeg Exp $

+ * @version $Id: TriggerDriver.java,v 1.3 2013/03/20 00:09:42 meeg Exp $

  */
 public abstract class TriggerDriver extends TriggerableDriver {
 

@@ -34,6 +35,7 @@

     private static boolean triggerBit = false;
     private String lcioFile = null;
     LCIOWriter lcioWriter = null;

+    private static final List<TriggerableDriver> triggerables = new ArrayList<TriggerableDriver>();

 
     public TriggerDriver() {
         latency = 50.0;

@@ -96,6 +98,9 @@

 
         if (ClockSingleton.getClock() - lastTrigger > deadTime && triggerDecision(event)) {
             sendTrigger();

+            for (TriggerableDriver triggerable : triggerables) {
+                ReadoutTimestamp.addTimestamp(triggerable, event);
+            }

             triggerBit = true;
             lastTrigger = ClockSingleton.getClock();
             numTriggers++;

@@ -129,6 +134,22 @@

         checkTrigger(event);
     }
 

+    protected static boolean sendTrigger() {
+        for (TriggerableDriver triggerable : triggerables) {
+            if (!triggerable.isLive()) {
+                return false;
+            }
+        }
+        for (TriggerableDriver triggerable : triggerables) {
+            triggerable.addTrigger();
+        }
+        return true;
+    }
+
+    public static void addTriggerable(TriggerableDriver triggerable) {
+        triggerables.add(triggerable);
+    }
+

     @Override
     protected void processTrigger(EventHeader event) {
         if (outputStream != null) {

diff -u -r1.2 -r1.3
--- EcalReadoutDriver.java	19 Mar 2013 22:24:07 -0000	1.2
+++ EcalReadoutDriver.java	20 Mar 2013 00:09:42 -0000	1.3
@@ -12,7 +12,7 @@

  * Performs readout of ECal hits.
  *
  * @author Sho Uemura <[log in to unmask]>

- * @version $Id: EcalReadoutDriver.java,v 1.2 2013/03/19 22:24:07 meeg Exp $

+ * @version $Id: EcalReadoutDriver.java,v 1.3 2013/03/20 00:09:42 meeg Exp $

  */
 public abstract class EcalReadoutDriver<T> extends TriggerableDriver {
 

@@ -145,6 +145,14 @@

     protected void processTrigger(EventHeader event) {
     }
 

+    @Override
+    public double readoutDeltaT() {
+        double triggerTime = ClockSingleton.getTime() + latency;
+        int cycle = (int) Math.floor((triggerTime - readoutOffset + ClockSingleton.getDt()) / readoutPeriod);
+        double readoutTime = cycle * readoutPeriod + readoutOffset - ClockSingleton.getDt();
+        return readoutTime;
+    }
+

     //initialize buffers
     protected abstract void initReadout();
 }

\ No newline at end of file

diff -u -r1.1 -r1.2
--- TriggerableDriver.java	19 Mar 2013 22:24:07 -0000	1.1
+++ TriggerableDriver.java	20 Mar 2013 00:09:42 -0000	1.2
@@ -1,8 +1,6 @@

 package org.lcsim.hps.readout.ecal;
 

-import java.util.ArrayList;

 import java.util.LinkedList;

-import java.util.List;

 import java.util.Queue;
 import org.lcsim.event.EventHeader;
 import org.lcsim.hps.util.ClockSingleton;

@@ -12,13 +10,12 @@

  * A driver that accepts triggers from TriggerDriver.
  * To implement, write your own processTrigger(), and call checkTrigger() somewhere in process().
  * You might want to set your own default latency in your constructor.

- * nextReadoutTime() and isLive() are meant to be overridden if you're doing something unusual.

+ * readoutDeltaT() and isLive() are meant to be overridden if you're doing something unusual.

  * @author Sho Uemura <[log in to unmask]>

- * @version $Id: TriggerableDriver.java,v 1.1 2013/03/19 22:24:07 meeg Exp $

+ * @version $Id: TriggerableDriver.java,v 1.2 2013/03/20 00:09:42 meeg Exp $

  */
 public abstract class TriggerableDriver extends Driver {
 

-    private static final List<TriggerableDriver> triggerables = new ArrayList<TriggerableDriver>();

     private Queue<Double> triggerTimestamps = new LinkedList<Double>();
     protected double latency = 0.0; // [ns]
 

@@ -28,10 +25,10 @@

 
     /**
      * 

-     * @return next time checkTrigger() will be called

+     * @return time reference for hits written by this driver in response to a trigger

      */

-    public double nextReadoutTime() {
-        return ClockSingleton.getTime() + ClockSingleton.getDt();

+    public double readoutDeltaT() {
+        return ClockSingleton.getTime() + latency;

     }
 
     @Override

@@ -55,20 +52,4 @@

     public boolean isLive() {
         return true;
     }

-
-    protected static boolean sendTrigger() {
-        for (TriggerableDriver triggerable : triggerables) {
-            if (!triggerable.isLive()) {
-                return false;
-            }
-        }
-        for (TriggerableDriver triggerable : triggerables) {
-            triggerable.addTrigger();
-        }
-        return true;
-    }
-
-    public static void addTriggerable(TriggerableDriver triggerable) {
-        triggerables.add(triggerable);
-    }

 }

diff -u -r1.9 -r1.10
--- SimpleSvtReadout.java	19 Mar 2013 22:24:07 -0000	1.9
+++ SimpleSvtReadout.java	20 Mar 2013 00:09:43 -0000	1.10
@@ -28,7 +28,7 @@

 /**
  * 
  * @author Omar Moreno <[log in to unmask]>

- * @version $Id: SimpleSvtReadout.java,v 1.9 2013/03/19 22:24:07 meeg Exp $

+ * @version $Id: SimpleSvtReadout.java,v 1.10 2013/03/20 00:09:43 meeg Exp $

  */
 public class SimpleSvtReadout extends TriggerableDriver {
 

@@ -321,6 +321,14 @@

         }
     }
 

+    @Override
+    public double readoutDeltaT() {
+        double triggerTime = ClockSingleton.getTime() + latency;
+        int cycle = (int) Math.floor((triggerTime - readoutOffset + ClockSingleton.getDt()) / Apv25Constants.SAMPLING_INTERVAL);
+        double readoutTime = cycle * Apv25Constants.SAMPLING_INTERVAL + readoutOffset - ClockSingleton.getDt();
+        return readoutTime;
+    }
+

     private class APV25Pipeline extends RingBuffer {
 
         private int _trigger_latency = (int) Math.floor(270 / Apv25Constants.SAMPLING_INTERVAL);

diff -N HitTimePrintDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ HitTimePrintDriver.java	20 Mar 2013 00:09:43 -0000	1.1
@@ -0,0 +1,31 @@

+package org.lcsim.hps.users.meeg;
+
+import java.util.List;
+import org.lcsim.event.CalorimeterHit;
+import org.lcsim.event.EventHeader;
+import org.lcsim.event.TrackerHit;
+import org.lcsim.hps.readout.ecal.ReadoutTimestamp;
+import org.lcsim.util.Driver;
+
+/**
+ *
+ * @author Sho Uemura <[log in to unmask]>
+ * @version $Id: HitTimePrintDriver.java,v 1.1 2013/03/20 00:09:43 meeg Exp $
+ */
+public class HitTimePrintDriver extends Driver {
+
+    @Override
+    protected void process(EventHeader event) {
+
+        List<TrackerHit> trackerHits = event.get(TrackerHit.class, "StripClusterer_SiTrackerHitStrip1D");
+        List<CalorimeterHit> ecalHits = event.get(CalorimeterHit.class, "EcalCalHits");
+
+        System.out.println("Event with ECal timestamp " + ReadoutTimestamp.getTimestamp(ReadoutTimestamp.SYSTEM_ECAL, event) + ", SVT timestamp " + ReadoutTimestamp.getTimestamp(ReadoutTimestamp.SYSTEM_TRACKER, event));
+        for (CalorimeterHit hit : ecalHits) {
+            System.out.println("Ecal: " + (hit.getTime() + ReadoutTimestamp.getTimestamp(ReadoutTimestamp.SYSTEM_ECAL, event)));
+        }
+        for (TrackerHit hit : trackerHits) {
+            System.out.println("SVT: " + (hit.getTime() + ReadoutTimestamp.getTimestamp(ReadoutTimestamp.SYSTEM_TRACKER, event)));
+        }
+    }
+}