diff -N HPSEcalTimeEvolutionReadoutDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ HPSEcalTimeEvolutionReadoutDriver.java	23 Aug 2011 23:46:13 -0000	1.1
@@ -0,0 +1,69 @@

+package org.lcsim.hps.recon.ecal;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.lcsim.event.CalorimeterHit;
+import org.lcsim.geometry.IDDecoder;
+import org.lcsim.hps.util.RingBuffer;
+
+/**
+ * Performs readout of ECal hits.
+ * Simulates time evolution of preamp output pulse.
+ * 
+ * @author Sho Uemura <[log in to unmask]>
+ */
+public class HPSEcalTimeEvolutionReadoutDriver extends HPSEcalReadoutDriver {
+    //buffer for deposited energy
+    Map<Long, RingBuffer> eDepMap = null;
+    //length of ring buffer (in readout cycles)
+    int bufferLength = 1;
+    //minimum readout value to write a hit
+    double threshold = 0.0;
+
+    public HPSEcalTimeEvolutionReadoutDriver() {
+    }
+
+    public void setBufferLength(int bufferLength) {
+        this.bufferLength = bufferLength;
+    }
+
+    public void setThreshold(double threshold) {
+        this.threshold = threshold;
+    }
+
+    public List<CalorimeterHit> readHits() {
+        IDDecoder dec = ecal.getIDDecoder();
+        List<CalorimeterHit> hitList = new ArrayList<CalorimeterHit>();
+        for (Long cellID : eDepMap.keySet()) {
+            RingBuffer eDepBuffer = eDepMap.get(cellID);
+            if (eDepBuffer.currentValue() > threshold) {
+                dec.setID(cellID);
+                hitList.add(new RawCalorimeterHit(eDepBuffer.currentValue(), dec.getPosition(), 0.0, cellID, hitType, dec));
+            }
+            eDepBuffer.step();
+        }
+        return hitList;
+    }
+
+    public void putHits(List<CalorimeterHit> hits) {
+        //fill the readout buffers
+        for (CalorimeterHit hit : hits) {
+            RingBuffer eDepBuffer = eDepMap.get(hit.getCellID());
+            if (eDepBuffer == null) {
+                eDepBuffer = new RingBuffer(bufferLength);
+                eDepMap.put(hit.getCellID(), eDepBuffer);
+            }
+            eDepBuffer.addToCell(0, hit.getRawEnergy()); //TODO: put actual pulse shape here
+        }
+    }
+
+    public void initReadout() {
+        //initialize clock
+        clock = 0;
+        //initialize buffers
+        eDepMap = new HashMap<Long, RingBuffer>();
+    }
+}

\ No newline at end of file

diff -N HPSEcalSimpleReadoutDriver.java
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ HPSEcalSimpleReadoutDriver.java	23 Aug 2011 23:46:13 -0000	1.1
@@ -0,0 +1,51 @@

+package org.lcsim.hps.recon.ecal;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.lcsim.event.CalorimeterHit;
+import org.lcsim.geometry.IDDecoder;
+
+/**
+ * Performs readout of ECal hits.
+ * No time evolution - this just integrates all hits in a cycle.
+ * 
+ * @author Sho Uemura <[log in to unmask]>
+ */
+public class HPSEcalSimpleReadoutDriver extends HPSEcalReadoutDriver {
+    //buffer for deposited energy
+    Map<Long, Double> eDepMap = null;
+
+    public List<CalorimeterHit> readHits() {
+        IDDecoder dec = ecal.getIDDecoder();
+        List<CalorimeterHit> hitList = new ArrayList<CalorimeterHit>();
+        for (Long cellID : eDepMap.keySet()) {
+            dec.setID(cellID);
+            hitList.add(new RawCalorimeterHit(eDepMap.get(cellID), dec.getPosition(), 0.0, cellID, hitType, dec));
+        }
+        //reset hit integration
+        eDepMap = new HashMap<Long, Double>();
+        return hitList;
+    }
+
+    public void putHits(List<CalorimeterHit> hits) {
+        //fill the readout buffers
+        for (CalorimeterHit hit : hits) {
+            Double eDep = eDepMap.get(hit.getCellID());
+            if (eDep == null) {
+                eDepMap.put(hit.getCellID(), hit.getRawEnergy());
+            } else {
+                eDepMap.put(hit.getCellID(), eDep + hit.getRawEnergy());
+            }
+        }
+    }
+
+    public void initReadout() {
+        //initialize clock
+        clock = 0;
+        //initialize buffers
+        eDepMap = new HashMap<Long, Double>();
+    }
+}

\ No newline at end of file

diff -u -r1.6 -r1.7
--- HPSEcalReadoutDriver.java	23 Aug 2011 22:35:13 -0000	1.6
+++ HPSEcalReadoutDriver.java	23 Aug 2011 23:46:13 -0000	1.7
@@ -1,14 +1,10 @@

 package org.lcsim.hps.recon.ecal;
 

-import java.util.ArrayList;
-import java.util.HashMap;

 import java.util.List;

-import java.util.Map;

 
 import org.lcsim.event.CalorimeterHit;
 import org.lcsim.event.EventHeader;
 import org.lcsim.geometry.Detector;

-import org.lcsim.geometry.IDDecoder;

 import org.lcsim.geometry.Subdetector;
 import org.lcsim.util.Driver;
 

@@ -17,14 +13,12 @@

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

-public class HPSEcalReadoutDriver extends Driver implements ECalReadout {

+public abstract class HPSEcalReadoutDriver extends Driver {

 
     Subdetector ecal;
     String ecalCollectionName;
     String ecalName;
     String ecalRawCollectionName = "EcalRawHits";

-    //buffer for deposited energy
-    Map<Long, Double> eDepMap = null;

     int hitType = 11;
     //counts bunches for readout clock
     int clock;

@@ -68,12 +62,12 @@

     public void process(EventHeader event) {
         //System.out.println(this.getClass().getCanonicalName() + " - process");
         clock++;

-        

+

         // Get the list of ECal hits.
         List<CalorimeterHit> hits = event.get(CalorimeterHit.class, ecalCollectionName);
         if (hits == null)
             throw new RuntimeException("Event is missing ECal hits collection!");

-        

+

         //write hits into buffers
         putHits(hits);
 

@@ -83,34 +77,12 @@

         }
     }
 

-    public List<CalorimeterHit> readHits() {
-        IDDecoder dec = ecal.getIDDecoder();
-        List<CalorimeterHit> hitList = new ArrayList<CalorimeterHit>();
-        for (Long cellID : eDepMap.keySet()) {
-            dec.setID(cellID);
-            hitList.add(new RawCalorimeterHit(eDepMap.get(cellID), dec.getPosition(), 0.0, cellID, hitType, dec));
-        }
-        //reset hit integration
-        eDepMap = new HashMap<Long, Double>();
-        return hitList;
-    }

+    //read analog signal out of buffers and make hits; reset buffers
+    public abstract List<CalorimeterHit> readHits();

-    public void putHits(List<CalorimeterHit> hits) {
-        //fill the readout buffers
-        for (CalorimeterHit hit : hits) {
-            Double eDep = eDepMap.get(hit.getCellID());
-            if (eDep == null) {
-                eDepMap.put(hit.getCellID(), hit.getRawEnergy());
-            } else {
-                eDepMap.put(hit.getCellID(), eDep + hit.getRawEnergy());
-            }
-        }
-    }

+    //add deposited energy to buffers
+    public abstract void putHits(List<CalorimeterHit> hits);

-    public void initReadout() {
-        //initialize clock
-        clock = 0;
-        //initialize buffers
-        eDepMap = new HashMap<Long, Double>();
-    }

+    //initialize buffers
+    public abstract void initReadout();

 }

\ No newline at end of file