diff --git a/FSUDAQ.cpp b/FSUDAQ.cpp
index 4c34c8f..bcdd1b6 100644
--- a/FSUDAQ.cpp
+++ b/FSUDAQ.cpp
@@ -36,7 +36,6 @@ FSUDAQ::FSUDAQ(QWidget *parent) : QMainWindow(parent){
   scope = nullptr;
   digiSettings = nullptr;
   singleHistograms = nullptr;
-  histThread = nullptr;
   onlineAnalyzer = nullptr;
   runTimer = new QTimer();
   breakAutoRepeat = true;
@@ -323,17 +322,6 @@ FSUDAQ::~FSUDAQ(){
 
   if( scope ) delete scope;
 
-  if( histThread ){
-
-    if( !histThread->isStopped() ){
-      histThread->Stop();
-      histThread->quit();
-      histThread->wait();
-    }
-
-    delete histThread;
-  }
-
   if( singleHistograms ) delete singleHistograms;
 
   if( onlineAnalyzer ) delete onlineAnalyzer;
@@ -743,12 +731,6 @@ void FSUDAQ::OpenDigitizers(){
   }
 
   singleHistograms = new SingleSpectra(digi, nDigi, rawDataPath);
-  histThread = new TimingThread(this);
-  histThread->SetWaitTimeinSec(singleHistograms->GetMaxFillTime()/1000.);
-  connect(histThread, &TimingThread::timeUp, this, [=](){
-    if( singleHistograms == nullptr &&   !singleHistograms->IsFillHistograms()) return; 
-    singleHistograms->FillHistograms();
-  });
 
   LogMsg("====== <font style=\"color: blue;\"><b>" + QString("Done. Opened %1 digitizer(s).").arg(nDigi) + "</b></font> =====");
 
@@ -784,22 +766,12 @@ void FSUDAQ::CloseDigitizers(){
   scalarThread->exit();
   CleanUpScalar();
 
-  if( histThread){
-    histThread->Stop();
-    histThread->quit();
-    histThread->wait();
-
-    delete histThread;
-    histThread = nullptr;
-  }
-
   if( onlineAnalyzer ){
     onlineAnalyzer->close();
     delete onlineAnalyzer;
     onlineAnalyzer = nullptr;
   }
 
-
   if( singleHistograms ){
     singleHistograms->close();
     delete singleHistograms;
@@ -1054,6 +1026,9 @@ void FSUDAQ::OpenScalar(){
 
 void FSUDAQ::UpdateScalar(){
   DebugPrint("%s", "FSUDAQ");
+
+  // printf("================== FSUDAQ::%s\n", __func__);
+
   if( digi == nullptr ) return;
   if( scalar == nullptr ) return;
   //if( !scalar->isVisible() ) return;
@@ -1066,6 +1041,7 @@ void FSUDAQ::UpdateScalar(){
 
   uint64_t totalFileSize = 0;
   for( unsigned int iDigi = 0; iDigi < nDigi; iDigi++){
+    // printf("======== digi-%d\n", iDigi);
     if( digi[iDigi]->IsBoardDisabled() ) continue;
 
     uint32_t acqStatus = digi[iDigi]->GetACQStatusFromMemory();
@@ -1107,6 +1083,7 @@ void FSUDAQ::UpdateScalar(){
     }
 
     // digiMTX[iDigi].unlock();
+    // printf("============= end of  FSUDAQ::%s\n", __func__);
 
   }
 
@@ -1181,7 +1158,7 @@ void FSUDAQ::StartACQ(){
   }
   lbScalarACQStatus->setText("<font style=\"color: green;\"><b>ACQ On</b></font>");
 
-  if( singleHistograms != nullptr ) histThread->start();
+  if( singleHistograms != nullptr ) singleHistograms->startWork();
 
   bnStartACQ->setEnabled(false);
   bnStartACQ->setStyleSheet("");
@@ -1256,13 +1233,9 @@ void FSUDAQ::StopACQ(){
   }
 
   if( onlineAnalyzer ) onlineAnalyzer->StopThread();
+  if( singleHistograms ) singleHistograms->stopWork();
+  
 
-  if( singleHistograms && histThread->isRunning()){
-    histThread->Stop();
-    histThread->quit();
-    histThread->wait();
-    singleHistograms->ClearInternalDataCount();
-  }
   lbScalarACQStatus->setText("<font style=\"color: red;\"><b>ACQ Off</b></font>");
 
   bnStartACQ->setEnabled(true);
@@ -1755,19 +1728,14 @@ void FSUDAQ::OpenScope(){
       }
 
       if( digiSettings ) digiSettings->setEnabled(!onOff);
-
-      if( singleHistograms ){
-        if( onOff) {
-          histThread->start();
+      if( singleHistograms ) {
+        if( onOff ) {
+          singleHistograms->startWork();
         }else{
-          if( histThread->isRunning()){
-            histThread->Stop();
-            histThread->quit();
-            histThread->wait();
-            singleHistograms->ClearInternalDataCount();
-          }
+          singleHistograms->stopWork();
         }
       }
+
     });
 
     connect(scope, &Scope::UpdateScaler, this, &FSUDAQ::UpdateScalar);
diff --git a/FSUDAQ.h b/FSUDAQ.h
index 751dd93..90423ec 100644
--- a/FSUDAQ.h
+++ b/FSUDAQ.h
@@ -194,7 +194,7 @@ private:
 
   //@----- SingleSpectra
   SingleSpectra * singleHistograms;
-  TimingThread * histThread;
+  // TimingThread * histThread;
 
   //@----- Analyzer
   Analyzer * onlineAnalyzer;
diff --git a/SingleSpectra.cpp b/SingleSpectra.cpp
index 346af9f..a6de8ee 100644
--- a/SingleSpectra.cpp
+++ b/SingleSpectra.cpp
@@ -18,8 +18,6 @@ SingleSpectra::SingleSpectra(Digitizer ** digi, unsigned int nDigi, QString rawD
   isSignalSlotActive = true;
 
   setWindowTitle("Single Histograms");
-  
-  //setWindowFlags( this->windowFlags() & ~Qt::WindowCloseButtonHint );
 
   //====== resize window if screen too small
   QScreen * screen = QGuiApplication::primaryScreen();
@@ -29,7 +27,6 @@ SingleSpectra::SingleSpectra(Digitizer ** digi, unsigned int nDigi, QString rawD
   }else{
     setGeometry(0, 0, 1000, 800);
   }
-  // setGeometry(0, 0, 1000, 800);
 
   QWidget * layoutWidget = new QWidget(this);
   setCentralWidget(layoutWidget);
@@ -174,11 +171,10 @@ SingleSpectra::SingleSpectra(Digitizer ** digi, unsigned int nDigi, QString rawD
 
     });
 
-    QCheckBox * chkIsFillHistogram = new QCheckBox("Fill Histograms", this);
+    chkIsFillHistogram = new QCheckBox("Fill Histograms", this);
     ctrlLayout->addWidget(chkIsFillHistogram, 0, 8);
-    connect(chkIsFillHistogram, &QCheckBox::stateChanged, this, [=](int state){ fillHistograms = state;});
     chkIsFillHistogram->setChecked(false);
-    fillHistograms = false;
+    isFillingHistograms = false;
 
     QLabel * lbSettingPath = new QLabel( settingPath , this);
     ctrlLayout->addWidget(lbSettingPath, 1, 0, 1, 6);
@@ -237,10 +233,28 @@ SingleSpectra::SingleSpectra(Digitizer ** digi, unsigned int nDigi, QString rawD
   ClearInternalDataCount();
 
 
+  workerThread = new QThread(this);
+  histWorker = new HistWorker(this);
+  timer = new QTimer(this);
+
+  histWorker->moveToThread(workerThread);
+
+  // Setup the timer to trigger every second
+  connect(timer, &QTimer::timeout, histWorker, &HistWorker::FillHistograms);
+  workerThread->start();
+
 }
 
 SingleSpectra::~SingleSpectra(){
   DebugPrint("%s", "SingleSpectra");
+
+  timer->stop();
+
+  if( workerThread->isRunning() ){
+    workerThread->quit();
+    workerThread->wait();
+  }
+
   SaveSetting();
 
   for( unsigned int i = 0; i < nDigi; i++ ){
@@ -309,82 +323,6 @@ void SingleSpectra::ChangeHistView(){
 
 }
 
-void SingleSpectra::FillHistograms(){
-  // DebugPrint("%s", "SingleSpectra");
-  if( !fillHistograms ) return;
-
-  timespec t0, t1;
-
-  QVector<int> randomDigiList = generateNonRepeatedCombination(nDigi);
-
-  // qDebug() << randomDigiList;
-
-  for( int i = 0; i < nDigi; i++){
-    int ID = randomDigiList[i];
-
-    QVector<int> randomChList = generateNonRepeatedCombination(digi[ID]->GetNumInputCh());
-
-    // qDebug() << randomChList;
-
-    // digiMTX[ID].lock();
-
-    // digi[ID]->GetData()->PrintAllData();
-
-    clock_gettime(CLOCK_REALTIME, &t0);
-    for( int k = 0; k < digi[ID]->GetNumInputCh(); k ++ ){
-      int ch = randomChList[k];
-      int lastIndex = digi[ID]->GetData()->GetDataIndex(ch);
-      // printf("--- ch %2d | last index %d \n", ch, lastIndex);
-      if( lastIndex < 0 ) continue;
-
-      int loopIndex = digi[ID]->GetData()->GetLoopIndex(ch);
-
-      int temp1 = lastIndex + loopIndex * digi[ID]->GetData()->GetDataSize();
-      int temp2 = lastFilledIndex[ID][ch] + loopFilledIndex[ID][ch] * digi[ID]->GetData()->GetDataSize() + 1;
-
-      // printf("loopIndx : %d | ID now : %d, ID old : %d \n", loopIndex, temp1, temp2);
-
-      if( temp1 <= temp2 ) continue;
-
-      if( temp1 - temp2 > digi[ID]->GetData()->GetDataSize() ) { //DefaultDataSize = 10k
-        temp2 = temp1 - digi[ID]->GetData()->GetDataSize();
-        lastFilledIndex[ID][ch] = lastIndex;
-        lastFilledIndex[ID][ch] = loopIndex - 1;
-      }
-
-      // printf("ch %d | regulated  ID now %d  new %d | last fill idx %d\n", ch, temp2, temp1, lastFilledIndex[ID][ch]);
-      
-      for( int j = 0 ; j <= temp1 - temp2; j ++){
-        lastFilledIndex[ID][ch] ++;
-        if( lastFilledIndex[ID][ch] > digi[ID]->GetData()->GetDataSize() ) {
-          lastFilledIndex[ID][ch] = 0;
-          loopFilledIndex[ID][ch] ++;
-        }
-
-        uShort data = digi[ID]->GetData()->GetEnergy(ch, lastFilledIndex[ID][ch]);
-
-        // printf(" ch: %d, last fill idx : %d | %d \n", ch, lastFilledIndex[ID][ch], data);
-
-        hist[ID][ch]->Fill( data );
-        if( digi[i]->GetDPPType() == DPPTypeCode::DPP_PSD_CODE ){
-          uShort e2 = digi[ID]->GetData()->GetEnergy2(ch, lastFilledIndex[ID][ch]);
-          // printf("%u \n", e2);
-          hist[ID][ch]->Fill( e2, 1);
-        }
-        hist2D[ID]->Fill(ch, data);
-      }
-      if( histVisibility[ID][ch]  ) hist[ID][ch]->UpdatePlot();
-
-      clock_gettime(CLOCK_REALTIME, &t1);
-      if( t1.tv_nsec - t0.tv_nsec + (t1.tv_sec - t0.tv_sec)*1e9 > maxFillTimePerDigi * 1e6 ) break;  
-    }
-
-    if( hist2DVisibility[ID] ) hist2D[ID]->UpdatePlot();
-    // digiMTX[ID].unlock();
-
-  }
-}
-
 void SingleSpectra::SaveSetting(){
   DebugPrint("%s", "SingleSpectra");
 
diff --git a/SingleSpectra.h b/SingleSpectra.h
index 721f05c..491bb99 100644
--- a/SingleSpectra.h
+++ b/SingleSpectra.h
@@ -20,6 +20,7 @@
 #include "Histogram1D.h"
 #include "Histogram2D.h"
 
+class HistWorker; //Forward decalration
 
 //^====================================================
 //^====================================================
@@ -31,8 +32,8 @@ public:
   ~SingleSpectra();
 
   void ClearInternalDataCount();
-  void SetFillHistograms(bool onOff) { fillHistograms = onOff;}
-  bool IsFillHistograms() const {return fillHistograms;}
+  // void SetFillHistograms(bool onOff) { fillHistograms = onOff;}
+  // bool IsFillHistograms() const {return fillHistograms;}
 
   void LoadSetting();
   void SaveSetting();
@@ -42,20 +43,39 @@ public:
 
   QVector<int> generateNonRepeatedCombination(int size);
 
-public slots:
-  void FillHistograms();
-  void ChangeHistView();
 
-private:
+  /// This should be private....
+  int lastFilledIndex[MaxNDigitizer][MaxNChannels];
+  int loopFilledIndex[MaxNDigitizer][MaxNChannels];
+  bool histVisibility[MaxNDigitizer][MaxNChannels];
+  bool hist2DVisibility[MaxNDigitizer];
+  unsigned short maxFillTimePerDigi;
+
+  bool isFillingHistograms;
+  Histogram1D * hist[MaxNDigitizer][MaxNChannels];
+  Histogram2D * hist2D[MaxNDigitizer];
 
   Digitizer ** digi;
   unsigned short nDigi;
 
-  Histogram1D * hist[MaxNDigitizer][MaxNChannels];
-  Histogram2D * hist2D[MaxNDigitizer];
+  void startWork(){ 
+    printf("timer start\n");
+    timer->start(maxFillTimeinMilliSec); 
+  } 
+  void stopWork(){ 
+    printf("timer stop\n");
+    timer->stop();
+    ClearInternalDataCount();
+  }
+
+  QCheckBox * chkIsFillHistogram;
+
+public slots:
+  // void FillHistograms();
+  void ChangeHistView();
+
+private:
 
-  bool histVisibility[MaxNDigitizer][MaxNChannels];
-  bool hist2DVisibility[MaxNDigitizer];
 
   RComboBox * cbDivision;
 
@@ -66,17 +86,110 @@ private:
   QGridLayout * histLayout;
   int oldBd, oldCh;
 
-  int lastFilledIndex[MaxNDigitizer][MaxNChannels];
-  int loopFilledIndex[MaxNDigitizer][MaxNChannels];
-
-  bool fillHistograms;
-
   QString settingPath;
 
   unsigned short maxFillTimeinMilliSec;
-  unsigned short maxFillTimePerDigi;
 
   bool isSignalSlotActive;
 
+  QThread * workerThread;
+  HistWorker * histWorker;
+  QTimer * timer;
+
 };
+
+//^#======================================================== HistWorker
+class HistWorker : public QObject{
+  Q_OBJECT
+public:
+  HistWorker(SingleSpectra * parent): SS(parent){}
+
+public slots:
+  void FillHistograms(){
+
+    // printf("%s | %d %d \n", __func__, SS->chkIsFillHistogram->checkState(), SS->isFillingHistograms);
+    if( SS->chkIsFillHistogram->checkState() == Qt::Unchecked ) return;
+    if( SS->isFillingHistograms) return;
+
+    SS->isFillingHistograms = true;
+    timespec t0, t1;
+
+    QVector<int> randomDigiList = SS->generateNonRepeatedCombination(SS->nDigi);
+
+    // qDebug() << randomDigiList;
+
+    for( int i = 0; i < SS->nDigi; i++){
+      int ID = randomDigiList[i];
+
+      QVector<int> randomChList = SS->generateNonRepeatedCombination(SS->digi[ID]->GetNumInputCh());
+
+      // qDebug() << randomChList;
+      // digiMTX[ID].lock();
+      // digi[ID]->GetData()->PrintAllData();
+
+      clock_gettime(CLOCK_REALTIME, &t0);
+      for( int k = 0; k < SS->digi[ID]->GetNumInputCh(); k ++ ){
+        int ch = randomChList[k];
+        int lastIndex = SS->digi[ID]->GetData()->GetDataIndex(ch);
+        if( lastIndex < 0 ) continue;
+        printf("--- ch %2d | last index %d \n", ch, lastIndex);
+
+        int loopIndex = SS->digi[ID]->GetData()->GetLoopIndex(ch);
+
+        int temp1 = lastIndex + loopIndex * SS->digi[ID]->GetData()->GetDataSize();
+        int temp2 = SS->lastFilledIndex[ID][ch] + SS->loopFilledIndex[ID][ch] * SS->digi[ID]->GetData()->GetDataSize() + 1;
+
+        // printf("loopIndx : %d | ID now : %d, ID old : %d \n", loopIndex, temp1, temp2);
+
+        if( temp1 <= temp2 ) continue;
+
+        if( temp1 - temp2 > SS->digi[ID]->GetData()->GetDataSize() ) { //DefaultDataSize = 10k
+          temp2 = temp1 - SS->digi[ID]->GetData()->GetDataSize();
+          SS->lastFilledIndex[ID][ch] = lastIndex;
+          SS->lastFilledIndex[ID][ch] = loopIndex - 1;
+        }
+
+        // printf("ch %d | regulated  ID now %d  new %d | last fill idx %d\n", ch, temp2, temp1, lastFilledIndex[ID][ch]);
+        
+        for( int j = 0 ; j <= temp1 - temp2; j ++){
+          SS->lastFilledIndex[ID][ch] ++;
+          if( SS->lastFilledIndex[ID][ch] > SS->digi[ID]->GetData()->GetDataSize() ) {
+            SS->lastFilledIndex[ID][ch] = 0;
+            SS->loopFilledIndex[ID][ch] ++;
+          }
+
+          uShort data = SS->digi[ID]->GetData()->GetEnergy(ch, SS->lastFilledIndex[ID][ch]);
+
+          // printf(" ch: %d, last fill idx : %d | %d \n", ch, lastFilledIndex[ID][ch], data);
+
+          SS->hist[ID][ch]->Fill( data );
+          if( SS->digi[i]->GetDPPType() == DPPTypeCode::DPP_PSD_CODE ){
+            uShort e2 = SS->digi[ID]->GetData()->GetEnergy2(ch, SS->lastFilledIndex[ID][ch]);
+            // printf("%u \n", e2);
+            SS->hist[ID][ch]->Fill( e2, 1);
+          }
+          SS->hist2D[ID]->Fill(ch, data);
+        }
+        if( SS->histVisibility[ID][ch]  ) SS->hist[ID][ch]->UpdatePlot();
+
+        clock_gettime(CLOCK_REALTIME, &t1);
+        if( t1.tv_nsec - t0.tv_nsec + (t1.tv_sec - t0.tv_sec)*1e9 > SS->maxFillTimePerDigi * 1e6 ) break;  
+      }
+
+      if( SS->hist2DVisibility[ID] ) SS->hist2D[ID]->UpdatePlot();
+      // digiMTX[ID].unlock();
+
+    }
+
+    SS->isFillingHistograms = false;
+    emit workDone();
+  }
+
+signals:
+  void workDone();
+
+private:
+  SingleSpectra * SS;
+};
+
 #endif
\ No newline at end of file