diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -55,9 +55,10 @@ else (BUILD_QWT)
 endif (BUILD_QWT)
 
 include(BuildQColorWidgets)
+include(BuildLedWidget)
 
 # includes
-include_directories("./src" ${QWT_INCLUDE_DIR} ${QCW_INCLUDE_DIR})
+include_directories("./src" ${QWT_INCLUDE_DIR} ${QCW_INCLUDE_DIR} ${LEDW_INCLUDE_DIR})
 
 # flags
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${QCW_FLAGS}")
@@ -133,11 +134,11 @@ add_executable(${PROGRAM_NAME} WIN32
   )
 
 # Use the Widgets module from Qt 5.
-target_link_libraries(${PROGRAM_NAME} ${QWT_LIBRARY} ${QCW_LIBRARY})
+target_link_libraries(${PROGRAM_NAME} ${QWT_LIBRARY} ${QCW_LIBRARY} ${LEDW_LIBRARY})
 qt5_use_modules(${PROGRAM_NAME} Widgets SerialPort)
 
 if (BUILD_QWT)
-  add_dependencies(${PROGRAM_NAME} QWT)
+  add_dependencies(${PROGRAM_NAME} QWT LEDW)
 endif (BUILD_QWT)
 
 # set compiler flags
diff --git a/cmake/modules/BuildLedWidget.cmake b/cmake/modules/BuildLedWidget.cmake
new file mode 100644
--- /dev/null
+++ b/cmake/modules/BuildLedWidget.cmake
@@ -0,0 +1,31 @@
+#
+# Copyright © 2017 Hasan Yavuz Özderya
+#
+# This file is part of serialplot.
+#
+# serialplot is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# serialplot is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with serialplot.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+include(ExternalProject)
+
+ExternalProject_Add(LEDW
+  PREFIX ledw
+  HG_REPOSITORY https://bitbucket.org/hyOzd/ledwidget
+  UPDATE_COMMAND ""
+  INSTALL_COMMAND "")
+
+ExternalProject_Get_Property(LEDW binary_dir source_dir)
+set(LEDW_INCLUDE_DIR ${source_dir}/src)
+message(${LEDW_INCLUDE_DIR})
+set(LEDW_LIBRARY ${binary_dir}/libledwidget.a)
diff --git a/src/portcontrol.cpp b/src/portcontrol.cpp
--- a/src/portcontrol.cpp
+++ b/src/portcontrol.cpp
@@ -1,5 +1,5 @@
 /*
-  Copyright © 2016 Hasan Yavuz Özderya
+  Copyright © 2017 Hasan Yavuz Özderya
 
   This file is part of serialplot.
 
@@ -130,6 +130,9 @@ PortControl::PortControl(QSerialPort* po
                      SELECT<int>::OVERLOAD_OF(&QButtonGroup::buttonClicked),
                      this, &PortControl::selectFlowControl);
 
+    // test code
+    connect(ui->pbDTR, &QPushButton::clicked, ui->ledDTR, &LedWidget::toggle);
+
     loadPortList();
     loadBaudRateList();
     ui->cbBaudRate->setCurrentIndex(ui->cbBaudRate->findText("9600"));
diff --git a/src/portcontrol.ui b/src/portcontrol.ui
--- a/src/portcontrol.ui
+++ b/src/portcontrol.ui
@@ -301,6 +301,81 @@
       </widget>
      </item>
      <item>
+      <layout class="QGridLayout" name="gridLayout_2">
+       <property name="spacing">
+        <number>2</number>
+       </property>
+       <item row="0" column="0">
+        <spacer name="horizontalSpacer_2">
+         <property name="orientation">
+          <enum>Qt::Horizontal</enum>
+         </property>
+         <property name="sizeHint" stdset="0">
+          <size>
+           <width>40</width>
+           <height>20</height>
+          </size>
+         </property>
+        </spacer>
+       </item>
+       <item row="0" column="1">
+        <widget class="QPushButton" name="pbDTR">
+         <property name="maximumSize">
+          <size>
+           <width>40</width>
+           <height>16777215</height>
+          </size>
+         </property>
+         <property name="text">
+          <string>DTR</string>
+         </property>
+        </widget>
+       </item>
+       <item row="0" column="2">
+        <widget class="LedWidget" name="ledDTR" native="true">
+         <property name="minimumSize">
+          <size>
+           <width>15</width>
+           <height>15</height>
+          </size>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>15</width>
+           <height>15</height>
+          </size>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="1">
+        <widget class="QLabel" name="labDCE">
+         <property name="text">
+          <string>DCE</string>
+         </property>
+         <property name="alignment">
+          <set>Qt::AlignCenter</set>
+         </property>
+        </widget>
+       </item>
+       <item row="1" column="2">
+        <widget class="LedWidget" name="ledDCE" native="true">
+         <property name="minimumSize">
+          <size>
+           <width>15</width>
+           <height>15</height>
+          </size>
+         </property>
+         <property name="maximumSize">
+          <size>
+           <width>15</width>
+           <height>15</height>
+          </size>
+         </property>
+        </widget>
+       </item>
+      </layout>
+     </item>
+     <item>
       <spacer name="verticalSpacer">
        <property name="orientation">
         <enum>Qt::Vertical</enum>
@@ -317,6 +392,14 @@
    </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>LedWidget</class>
+   <extends>QWidget</extends>
+   <header>ledwidget.h</header>
+   <container>1</container>
+  </customwidget>
+ </customwidgets>
  <tabstops>
   <tabstop>cbPortList</tabstop>
   <tabstop>pbReloadPorts</tabstop>