diff --git a/mainwindow.cpp b/mainwindow.cpp
new file mode 100644
--- /dev/null
+++ b/mainwindow.cpp
@@ -0,0 +1,150 @@
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+#include <QSerialPortInfo>
+#include <QtDebug>
+
+#include "utils.h"
+
+MainWindow::MainWindow(QWidget *parent) :
+    QMainWindow(parent),
+    ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+
+    // init UI signals
+    QObject::connect(ui->pbReloadPorts, &QPushButton::clicked,
+                     this, &MainWindow::loadPortList);
+
+    QObject::connect(ui->pbOpenPort, &QPushButton::clicked,
+                     this, &MainWindow::togglePort);
+
+    QObject::connect(this, &MainWindow::portToggled,
+                     this, &MainWindow::onPortToggled);
+
+    QObject::connect(ui->cbPortList,
+                     SELECT<const QString&>::OVERLOAD_OF(&QComboBox::activated),
+                     this, &MainWindow::selectPort);
+
+    QObject::connect(ui->cbBaudRate,
+                     SELECT<const QString&>::OVERLOAD_OF(&QComboBox::activated),
+                     this, &MainWindow::selectBaudRate);
+
+    QObject::connect(&(this->serialPort), &QSerialPort::readyRead,
+                     this, &MainWindow::onDataReady);
+
+    loadPortList();
+    loadBaudRateList();
+    ui->cbBaudRate->setCurrentIndex(ui->cbBaudRate->findText("9600"));
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
+
+void MainWindow::loadPortList()
+{
+    QString currentSelection = ui->cbPortList->currentText();
+
+    ui->cbPortList->clear();
+
+    for (auto port : QSerialPortInfo::availablePorts())
+    {
+        ui->cbPortList->addItem(port.portName());
+    }
+
+    // find current selection in the new list, maybe it doesn't exist anymore?
+    int currentSelectionIndex = ui->cbPortList->findText(currentSelection);
+    if (currentSelectionIndex >= 0)
+    {
+        ui->cbPortList->setCurrentIndex(currentSelectionIndex);
+    }
+    else // our port doesn't exist anymore, close port if it's open
+    {
+        if (serialPort.isOpen()) togglePort();
+    }
+}
+
+void MainWindow::loadBaudRateList()
+{
+    ui->cbBaudRate->clear();
+
+    for (auto baudRate : QSerialPortInfo::standardBaudRates())
+    {
+        ui->cbBaudRate->addItem(QString::number(baudRate));
+    }
+}
+
+void MainWindow::togglePort()
+{
+    if (serialPort.isOpen())
+    {
+        serialPort.close();
+        qDebug() << "Port closed, " << serialPort.portName();
+        emit portToggled(false);
+    }
+    else
+    {
+        serialPort.setPortName(ui->cbPortList->currentText());
+
+        // open port
+        if (serialPort.open(QIODevice::ReadWrite))
+        {
+            qDebug() << "Port opened, " << serialPort.portName();
+            emit portToggled(true);
+
+            // set baud rate
+            if (!serialPort.setBaudRate(ui->cbBaudRate->currentText().toInt()))
+            {
+                qDebug() << "Set baud rate failed during port opening: "
+                         << serialPort.error();
+            }
+        }
+        else
+        {
+            qDebug() << "Port open error: " << serialPort.error();
+        }
+    }
+}
+
+void MainWindow::selectPort(QString portName)
+{
+    // has selection actually changed
+    if (portName != serialPort.portName())
+    {
+        // if another port is already open, close it by toggling
+        if (serialPort.isOpen())
+        {
+            togglePort();
+
+            // open new selection by toggling
+            togglePort();
+        }
+    }
+}
+
+void MainWindow::selectBaudRate(QString baudRate)
+{
+    if (serialPort.isOpen())
+    {
+        if (!serialPort.setBaudRate(baudRate.toInt()))
+        {
+            qDebug() << "Set baud rate failed during select: "
+                     << serialPort.error();
+        }
+        else
+        {
+            qDebug() << "Baud rate changed: " << serialPort.baudRate();
+        }
+    }
+}
+
+void MainWindow::onPortToggled(bool open)
+{
+    ui->pbOpenPort->setChecked(open);
+}
+
+void MainWindow::onDataReady()
+{
+    qDebug() << "Data: " << serialPort.readAll().toHex();
+}