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Sitara Linux Training: Hands on with QT

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This lab is going to give you a hands on tutorial on QT, the GUI devolpment tool, which is a component of the Sitara SDK. Each of the following sections below will walk you through a particular Lab exercise, the key points to take away, and the step-by-step instructions to complete the lab. The labs in this section will utilize both a command line build approach and a IDE approach using QT Creator.

Wiki Training: - You can find the necessary code segments embedded in the this wiki article. You can cut and paste them from the wiki as needed.

Hands On Session: - In the vmware image, there are cheater files: /home/sitara/QT_Lab You can cut and paste section of code from this file rather than have to type them in. You can find a copy here, just right click and select "Save Target As": File:QT Lab.tar.gz

NOTE: In this guide commands to be executed for each step will be marked in BOLD

Lab Configuration

The following are the hardware and software configurations for this lab. The steps in this lab are written against this configuration. The concepts of the lab will apply to other configurations but will need to be adapted accordingly.



All Sitara boards with an LCD display or HDMI/DVI out can be used for these labs, but the steps below related to serial and ethernet connections may differ.
  • Router connecting AM335x EVM-SK and Linux Host
  • USB cable connection between AM335x EVM-SK and Linux Host using the micro-USB connector (J3/USB0)

The AM335x EVM uses a standard DB9 connector and serial cable. New Win7 based Host PCs may require a USB-to-Serial cable since newer laptops do not have serial ports. Additionally, since the serial connection is not required for these labs, you can telnet or ssh into the target over ethernet instead of using a serial terminal for target interaction.
  • 5V power supply (typically provided with the AM335x EVM-SK)


  • A Linux host PC configured as per the Linux Host Configuration page
    • **PLEASE NOTE** currently the Linux Host Configuration page is under revision. Please download Ubuntu 14.04 rather than Ubuntu 12.04 at this link
  • Sitara Linux SDK installed. This lab assumes the latest Sitara Linux SDK is installed in /home/sitara. If you use a different location please modify the below steps accordingly.
  • SD card with Sitara Linux SDK installed.
  • QT Creator 5.7.0 installed on your Linux host.
    • You can download Qt Creator from open source distribution version of Qt
    • QT will download as a .run file. Make the file executable by running the chmod + <qtfile> command and ./<qtfile>. These steps should launch the QT installer.
    • Extract the package. Qt creator will be under Tools/Qt5.7.0 folder. In some cases it may also be under the opt folder. Type cd /opt/Qt5.7.0 into the command line to locate the file.
    • The labs in this wiki page is validated with Ubuntu 14.04 on 64 bit machine.

Supported Platforms and revisions

The following platforms are system tested to verify proper operation.

  • am335x
  • am37x
  • am35x
  • am180x
  • BeagleBoard XM

This current version has been validated on ti-processor-sdk version using QT Creator 3.6.0

LAB 1: Hello World Command Line


This LAB is optional, it introduces where to find QT components and build tools in the Sitara SDK. Approximate time to complete this LAB: 15 minutes. This section will cover the following topics

  • Introduction to build tools
  • enviroment setup script
  • The QT component of the Sitara SDK
    • where to find things in the Sitara SDK

Key Points

  • Where in the SDK to find the build tools
  • Where in the SDK to find the QT components
  • How to setup your build environment
  • How to utilize the above points to create a Hello World application.

Lab Steps

  1. Connect the cables to the EVM. For details on where to connect these cables see the Quick Start Guide that came with your EVM.
    1. Connect the Serial cable to provide access to the console.
    2. Connect the network cable
    3. Insert the SD card into the SD connector
    4. Insert the power cable into the 5V power jack
  2. Power on the EVM and allow the boot process to finish. You will know when the boot process has finished when you see the Matrix application launcher on the LCD screen

    You may be required to calibrate the touchscreen. If so follow the on screen instructions to calibrate the touchscreen.
  3. Open a terminal window on your Linux host by double clicking the Terminal icon on the desktop
  4. The cross-compiler is located in the linux-devkit/bin directory of the SDK installation directory. In the terminal window enter the following commands, replacing the <machine> and <sdk version> fields with the target machine you are using and the SDK version installed.

    You can use TAB completion to help with this
    • cd /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin
    • ls
  5. You should see a listing of the cross-compile tools available like the one below.
  6. To locate the pre-built ARM libraries perform the following commands:
    • cd /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/cortexa8hf-vfp-neon-linux-gnueabi/usr/lib
    • ls
  7. You should now see a listing of all the libraries (some are contained within their individual sub-directories) available as pre-built packages within the SDK.
  8. Now list only the QT libraries from the same directory by listing all libs starting with libQt.
    • ls libQt*
  9. You should see a listing of QT related libraries that can be used to build and run QT projects.
    Sitara Linux QT library listings 1.png
  10. You can also find out where the QT header files are located. At the directory below are sub directories full of QT header files.
    • cd /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/cortexa8hf-vfp-neon-linux-gnueabi/usr/include/qt5
    • ls
  11. In order to make it easier to perform cross-compilations and ensure linking with the proper cross-compiled libraries instead of the host system libraries the environment-setup script has been created in the linux-devkit directory. This script will configure many standard variables such as CC to use the cross-compile toolchain, as well as adding the toolchain to your PATH and configuring paths for library locations. To utilize the setting provided by the environment-setup script you will need to source the script. Perform the following commands to source the environment-setup script and observe the change in the QMAKESPEC variable:
    • echo $QMAKESPEC
    • source /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/environment-setup
    • echo $QMAKESPEC
  12. You should see the changes that were applied by executing the setup script.
    Sitara Linux QT environment setup script.jpeg
  13. You should have observed that the QMAKESPEC variable now contains the path to the QMAKESPEC files. Additionally your compile tools were added. There was also another change that occurred which was that your standard prompt changed from sitara@ubuntu to [linux-devkit]. The purpose of this change is to make it easy to identify when the environment-setup script has been sourced. This is important because there are times when you DO NOT want to source the environment-setup script. A perfect example is when building the Linux kernel. During the kernel build there are some applications that get compiled which are meant to be run on the host to assist in the kernel build process. If the environment-setup script has been sourced then the standard CC variable will cause these applications to be built for the ARM, which in turn will cause them to fail to execute on the x86 host system.
  14. As mentioned above sometimes it is not appropriate to source the environment-setup script, or you only want to source it during a particular build but not affect your default environment. The way this is done in the SDK is to source the environment-setup script inside of the project Makefile so that it is used only during the build process.
  15. Take a look at the enviroment setup file to see what all is going on there. Look through file to see where the compile tools variables such as CC and CPP and PATH are defined.
    • gedit /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/environment-setup
  16. It is now time to build a Hello World project using QT. You need to create two files: helloworld.cpp and
    • mkdir /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/example_applications/helloworld
    • cd /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/example_applications/helloworld
    • gedit helloworld.cpp and add the following code

      You can find pre-written files in the in the /home/sitara/sitara-training-helper-files/QT_Lab/lab1 directory. You can just copy those files to your directory instead of typing the contents if you want to

      #include <QApplication>
      #include <QLabel>
      int main(int argc, char **argv)
      QApplication app(argc,argv);
      QLabel label("Hello World");;
      return app.exec();
    • gedit and add code

      You can find pre-written files in the in the /home/sitara/sitara-training-helper-files/QT_Lab/lab1 directory. You can just copy those files to your directory instead of typing the contents if you want to

      QT += core gui widgets
      SOURCES += helloworld.cpp
  17. Now lets use qmake to create a Makefile
    • qmake
  18. Notice how qmake automatically generated a Makefile for us, now lets build.
    • make
  19. Notice the build is using our cross-compiler- arm-linux-gnueabihf-g++
    Sitara Linux QT make using cross compile.jpeg
  20. Also notice we now have an executable, lets see what type of file we created
    • file helloworld
  21. You should see something similar to the following: helloworld: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.31, BuildID[sha1]=0x8569a0956d8efffcfde68fca5c883be5fa4f1c31, not stripped
  22. Finally lets copy the helloworld over to our target file system and run it.
    • If you have not already done so connect with minicom and type ifconfig to find your target's ip address

      You can also get your ip address from Matrix if it is running. Select Settings->Network Settings
    • On your Linux host console issue the command scp -r helloworld root@xx.xx.xx.xx:/home/root replacing the xx.xx.xx.xx below with you target's ip address.
    • When asked for password, just hit return
    • Type yes when asked if you would like to continue
    • Move back over to your minicom window and execute it. You should find the helloworld in your default /home/root directory on the target.
      • ./helloworld
  23. You should see helloworld print on the LCD panel of your target board.

LAB 2: QT Creator Hello World


This section will cover setting up QT Creator the integrated development environment. We start to investigate how QT Creator aids in rapid GUI development.

Key Points

  • Setting up QT Creator to find your tools
  • Setting up QT Creator to communicate with the target platform
  • Creating hello world and run using QT Creator.

Lab Steps

  1. Source the enviroment setup file to ensure all the paths are setup correctly. This was done in the previous section. If you already see [linux-devkit]: as your prompt then you can skip this step.
    • source /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/environment-setup
  2. Bring up Qt Creator
    • ./home/sitara/Qt5.7.0/Tools/QtCreator/bin/qtcreator

      By bringing QT Creator up manually, you will pass in the environment setup. If you double click on the Qt Creator Icon from the Desktop, you will not have the enviroment setup correctly and your lab will not work later on.
  3. QT creator should be up and running now
    Sitara Linux QT qtcreator.png
  4. Now lets setup QT creator to configure qmake. From the QT creator main menu shown above select the following:
    • Tools -> Options...
    • On the left side vertical menubar click Build & Run
    • Click the Qt Versions tab under Build & Run
    • Remove any versions that may already exist to make sure you start with a clean configuration
    • Click Add... on the right
    • Navigate to /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin/qt5
    • Select qmake then click on Open
    • Double click on Version Name and give the Qt Version a descriptive name such as QT 5.5 Sitara See image below.
    Sitara Linux QT Options.jpeg

    Notice there is a red ! icon. Don't worry, lets add in the toolchain next and it should change to yellow.
    • Click Apply to save your changes
  5. Now we will setup the toolchain
    • Click the Compiler tab under Build & Run
    • Click Add in the top right and add a GCC
    • Change the name to arm-linux-gnueabihf-gcc. This can be done by editing the "Name" field.
    • For Compiler Path select Browse
      • Navigate to /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin
      • Select arm-linux-gnueabihf-gcc and click on open
      • Make sure to click on Apply to save your changes.
  6. Next, let’s setup the Debuggers.
    • Click the Debuggers tab under Build and Run
    • Click Add in the top right
    • Change the name to GDB Engine. This can be done by editing the "Name" field.
    • For Debugger Path select Browse
      • Navigate to /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/linux-devkit/sysroots/x86_64-arago-linux/usr/bin
      • Select arm-linux-gnueabihf-gdb and click on open
      • Make sure to click on Apply to save your changes.
  7. Click the Kits tab under Build & Run
    • Change the name to give the device a unique name: AM335x EVM
    • Select Device type Generic Linux Device instead of Desktop.
    • Select Compiler arm-linux-gnueabihf-gcc instead of the host gcc.
    • For Debugger select GDB Engine.
    • For QT Version select Qt 5.5 Sitara
    • Click Apply to register the options.
  8. Now let's setup our Target. While still in the Tools -> Options menu
    • On the left side of the window, select the Devices tab
    • In Devices: click the Devices tab
    • Click Add... in the top right
      Sitara Linux QT options add device.png
    • Select Generic Linux device and click on Start Wizard
      Sitara Linux QT Device Configuration Wizard Selection.jpeg
    • The Device Configuration Wizard Selection Dialog box comes up
      • Type in the name of the Device: AM335x EVM
      • Type in the IP address of the Embedded Linux Device. Type the IP address for your board, not the one shown in the screen capture.

        This is the same IP address you obtained in the previous lab
      • For Username type in root (Most Texas Instruments Boards have this username)
      • Make sure Authentication type is Password, but leave the password field blank.
      • Click Next
      Sitara Linux options Generic Linux Device Configuration Setup.jpeg
    • Click Finish. You should see that the target test passed, so you can close that window.
      Sitara target test.png
  9. Now we need to setup an SSH key so that the host can communicate with the target
    • Still under the Devices tab click Create New for Private key file
    Sitara Linux QT create new ssh key.png
      • Key algorithm RSA
      • Select Key size: 1024
      • Then click Generate and Save Key Pair...
    Sitara Linux QT options SSH Key Configuration.jpeg
      • Click Do not Encrypt key file
    Sitara Linux QT Password for Private Key.jpeg
      • Just use the default name and Click Save and Click Close to close the Generate SSH Key window.
    • Under the Devices tab now click Deploy Public Key...
    Sitara Linux QT Deploy Public Key.png
      • Select the file just generated (should be under /home/sitara/.ssh)

        You may need to right click and select show hidden files
      • Select the file and click on Open, shortly a window should show up saying "Deployment finished sucessfully"
        Sitara successful deploy.png
    • Close the window and Click OK to exit the Linux Devices Window.
    Sitara Linux QT ok to close devices.png
  10. Now that we are setup lets create a project build it and run it on the host
    • Select File -> New File or Project
    • Then select Applications under projects then select QT Widgets Applicaton on the top center
    • Click on Choose
      Sitara Linux QT new project.png
    • Type in the name of the project as terminal. We will be building on this project in the next section.
    • Change the Create in value to /home/sitara
    • Click on Next
      Sitarea Linux Qt project terminal.png
    • Click on Next again
    • Type in terminal for the Class name
    • Click Next
      Sitara Linux QT new terminal props.png
    • Click Finish
  11. Now we've setup a new project let's explore and add some code.
    • Click on Edit on the left hand menubar and look at the project files including, main.cpp, terminal.cpp and terminal.ui
    • Under Forms, double click on terminal.ui This will bring up the widget editor.
    • Remove the menuBar where it says Type Here on the top of the ui
    • Right click on the menuBar and select Remove MenuBar
    • Use the same procedure to remove the statusBar at the bottom of the ui. It is not that easy to see, but it is there and blank.
    • Once again remove the ToolBar (mainToolBar). It is found at the top of the ui and is also hard to see.
    • Find the label widget in the category of display widgets, left click and drag it on to the User Interface (UI).
    • Type Hello World!!! into the label widget and strech out the borders so you can see all the letters.
      Sitara hello world UI.png
  12. Now we need to check and update the build and run settings:
    • On the left side vertical menubar select Projects
    • Select the Build and Run tab and select Build under AM335x.
    • Uncheck Shadow build as shown in the screenshot below:
      Sitara Build settings 1.png
    • Now under the AM335x select the Run tab
    • Under Method click Add and select Add and then Deploy to Remote Linux Host
    • However you see the <Remote path not set> error under the Run secton.
      Sitara deploy remote.jpeg
    • To fix the <Remote path not set> error do the following:
      • Click on Edit on the left side vertical bar and click on
      • Add the two lines below to the bottom of as shown in the screen shot below

        You can find pre-written files in the in the /home/sitara/sitara-training-helper-files/QT_Lab/lab2 directory. You can just copy those files to your directory instead of typing the contents if you want to

        target.path += /home/root
        INSTALLS += target

        Sitara add target loc.jpeg
      • Select File -> Save
    • Click on Projects on the left side vertical bar and you should now see the error is gone and replaced with /home/root/terminal
    • Now in the Run portion: Select Add -> terminal (on Remote Generic Linux Host)
      Sitara remote host.jpeg
  13. Finally we are ready to run
    • Click the Green Arrow on the bottom left to run the project

      ti-processor-sdk-linux-<> version and has dropbear package that doesn't let the QT Creator to deploy the built image on the target board. dropbear version 2015.71 fixes this problem and the prebuilt binary can be download from here. Replace the /usr/sbin/dropbearmulti on target board filesystem with the downloaded 2015.71 dropbearmulti binary. Change the copied file mode to executable. Restart the target board. QT Creator should be able to successfully deploy the binary now
    • If you receive the error 'g++: Command not found', navigate to tools>options>build and run>kits. Add “linux-oe-g++” to the “Qt mkspec” text box
    • Save all files if asked
  14. Extra Investigation:
    • From minicom: run top on the target while helloworld is running. Check out CPU utilization and memory utilization for this simple app.
    • See how much memory is used by helloworld by itself, you may need to kill matrix /etc/init.d/matrix-gui-2.0 stop

LAB 3: Terminal project


This section shows how you can use QT Creator to create a GUI from scratch.

Key Points

  • Adding widgets to a an User Interface (ui).
  • Adding code to make the widgets do something meaningful.

Lab Steps

  1. We will continue on from the previous lab using the terminal project you created. First we will remove the Hello world widget and resize the ui.
    • Click terminal.ui to bring up design mode.
    • Click the Hello World widget, and delete it making the ui empty and clean
  2. This next action is mainly for those with small displays, but will not adversely affect larger displays.
    • Select the entire ui as shown below.
    • Edit the Geometry values to Width = 440 and Height = 230 as shown.
      Resize the GUI screen size
  3. Next we will add the Tab Widget. Just like the label widget, drag it over to the ui.
    Sitara tab widget.png
    • Select the tab widget layout. Currently, the tab widget is part of our ui, but it is just sitting at fixed location where we dragged it.
      • On the upper right side right click on the terminal QWidget and select Lay Out -> Lay Out Vertical as shown below
        Sitara layout vertically.png
    • Now the tab widget should completely fill the ui.
  4. Now let's ad
    • Two Push Button Widgets
    • One Text Browser widget
    • One Line Edit widget.
      • Drag all of them up to the ui
    • Now lets set the TabWidget layout like we did with the terminal widget
      • Right click on the upper right QtabWidget -> Lay Out -> Lay Out in a Grid
      • Move them around so they look somewhat like the screen shot below
        Sitara ui layout.jpeg
  5. Lets Rename the Push Button widgets.
    • Double click on the PushButton text in the ui
    • Edit the upper push button to say Send CMD
    • Edit the lower push botton to say Exit
    • Depending on how the grid layout worked for you, lets stretch out the Text Browser widget and the bottom Push Button widget to take up the whole screen horizontally if needed.
      • Just click on the widget and drag the border to fill the screen See screen shot below:
      Sitara adjust widths.png
  6. Now lets give our widget objects a unique name.
    • Select the Text Browser widget
    • Go over to properties on the bottom right and edit ObjectName
      • Add the text _linuxshell to the end of the textBrowser name as shown below:
      Sitara rename objects.jpeg
  7. Now create unique names for the other 3 widgets.
    • For lineEdit: lineEdit_commandline
    • For the Send CMD push button: pushButton_sendcmd
    • For exit push button: pushButton_exit
  8. We are not done yet, but for fun lets run this application and see what it looks like on the target.
    • Push the Green Arrow at the bottom left to launch on the target. Save all files if asked.

      You can not start a new application on the target if your previous one is still running. To exit, push the "X" on the menubar at the top right of your target.

      It should appear just as we designed it, but pushing the buttons has no effect because we haven't added any code yet.
  9. Now we are going to add code to make the buttons do what we wish them to do.
    • Right click on the Exit widget -> Go to slot
      Sitara goto slot.jpeg
    • In the Go to Slot selector, select the first selection clicked() and hit OK
  10. Notice this pops you over to your terminal.cpp file where some code has been automatically added for you.

    The code additions below can also be found in the /home/sitara/sitara-training-helper-files/QT_Lab/lab3 directory and can be copied into your project
    • Add the following line of code to on_pushButton_exit_clicked()


      Sitara pushbutton.png
  11. Now repeat the same process you did for the exit button on the send CMD button. We will add code to control that button press.

    You will need to go back to the ui file to do this
    • Right click on the Send CMD widget -> Go to slot
    • In the Go to Slot selector, select the first selection clicked() and hit OK
    • Add the following line at the top of terminal.cpp to support QProcess.

      #include <QtGui>

    • Add the following code to on_pushButton_sendCmd_clicked()

      QString LinuxTexttoSend = ui->lineEdit_commandline->text();
      // QProcess used to binaries in /usr/bin
      QProcess process;
      // Merge Channels so the output of binaries can be seen
      // Start whatever command is in LinuxTexttoSend
      process.start(LinuxTexttoSend, QIODevice::ReadWrite);
      // Run the command and loop the output into a QByteArray
      QByteArray data;

      Sitara SendCMD code.png
  12. Finally since we don't have a keyboard to type a command lets add a predefined command to our line Edit Widget like shown below:
    • Double click on the line edit and add the text: date --help
      Sitara add command.png
  13. Now run, you should see interaction with the Linux shell when you push sendCMD.

LAB 4: Enhancing the project with a web viewer, soft keyboard, and Style Sheets


In this section we Enhance our GUI with a web browser, soft keyboard and style sheets.

Key Points

  • Adding a Web view.
  • Adding a softkeyboard.
  • How to adjust the look and feel

Lab Steps

  1. One of the first things we did in the Terminal Lab was to add a Tab widget which is a container widget. So far we added a Linux shell terminal to Tab 1, now lets add a Web View widget to Tab 2
    • From the terminal.ui, click on Tab 2 and notice it is empty.
      • Drag over a QWebView widget to Tab 2
      • Set the Layout of Tab 2 to a vertical layout

        Do you recall how we did this on the Terminal Lab? On the top right, right click tabWidget -> Lay Out -> Lay Out Vertically
    • When complete with the above steps, it should look like the following:
      Sitara webview.jpeg
  2. Now we can add a default URL. Since we are not connected to the internet, lets bring up matrix since it is running on a local server.
    • Select the WebView widget and on the bottom right find the url property of QWebView near the bottom of the list.
    • Type in: http://localhost
      Sitara default url.png

      Notice how the Webview in your ui tries to display the webpage but can't since it is not local to your host. Some people see this error and some do not.
  3. Now we need to add the webkit libraries to our project.
    • Go to Edit mode and bring up the file
    • Add webkitwidgets as shown below
      Sitara webkitwidgets.png
  4. Give it a try and run it, you should see the Matrix displayed.

    You will need to use the Exit button on Tab1 to close this program
  5. Now lets address a couple of cosmetic issues. Notice how our new GUI does not fill the entire screen.
    • Change over to Edit' mode and bring up main.cpp.
    • Find the line
      • Remove that line
      • type w. and notice how QT Creator will fill in all the possible options. Also notice that when you start to type it will jump the available options with the matching text.
      • Select w.showFullScreen(); see screen shot.
      Sitara fullscreen.png
  6. Now re-run and notice how it takes up the full screen.
    Sitara matrix.PNG

    You will need to use the Exit button on Tab1 to close this program
  7. Now lets fix another issue back on Tab 1. We hard coded in a default command: date --help
    • Since we did not provide a keyboard, lets add a soft keyboard.
      • Download a keyboard class from this location: Qt Keyboard Template wiki. These instruction assume you downloaded the tarball to the /home/sitara directory.

        If you are using a TI laptop or followed the host configuration steps you can find these files in the /home/sitara/sitara-training-helper-files/QT_Lab/keyboard directory and can skip these steps
        • cd /home/sitara
        • tar -xzvf Keyboard.tar.gz
      • Copy the keyboard files to your terminal project directory
        • cd /home/sitara/terminal/
        • cp -rf <keyboard extraction directory>/keyboard .
    • Now lets add keyboard into our project.
      • Go to Edit mode and right click on terminal -> Add Existing Files as shown below.
        Sitara addexisting.png
      • Navigate to the keyboard directory /home/sitara/terminal/keyboard and add all 4 files in that directory.
        Sitara addkeyboard.png

        Notice how all four keyboard files are now part of the Terminal project. Click on the keyboard.ui and take a look. It is made up mainly of QPushButtons and one QLineEdit and layout controls
    • Now we need to hook in the keyboard to the terminal GUI.

      As always you can find copy that you can copy into your project in the /home/sitara/sitara-training-helper-files/QT_Lab/lab4 directory
      • Add some code to terminal.h
        • At the top of the file add
          #include "keyboard/keyboard.h"
        • In private slots: add
          void open_keyboard_lineEdit();
        • In the section private: add
          Keyboard *lineEditkeyboard;

          Sitara terminal h.png
      • Now add some code to terminal.cpp
        • In the function terminal::terminal

          lineEditkeyboard = new Keyboard();
          connect( ui->lineEdit_commandline ,SIGNAL(selectionChanged()),this ,SLOT(open_keyboard_lineEdit()));

        • Also add the function below to the bottom of terminal.cpp
          void terminal::open_keyboard_lineEdit()
          QLineEdit *line = (QLineEdit *)sender();

          Sitara terminal cpp.jpeg
  8. You are now ready to run your code.
    • Run and verify when you touch the line edit widget, that the keyboard pops up.

      Depending on your screen resolution you may need to double-tap the bar at the top of the keyboard to size it to full screen
  9. Type in a linux command such as ps to list the running processes and verify that you get back the expected results.
  10. Next lets add specific colors to the GUI components using style sheets.
    • Go back to your ui in the upper right corner: right click on the terminal widget -> Change styleSheet
      Sitara stylesheet.jpeg
    • Cut and paste from terminal sytle sheet settings at the end of this lab section to the Terminal stylesheet settings and Apply them

      You can find this file in the /home/sitara/sitara-training-helper-files/QT_Lab/lab4/style_sheet_terminal.txt file
    • Do the same thing for the Tab Widget by cutting and pasting from the tab style sheet settings at the end of this Lab section

      You can find this file in the /home/sitara/sitara-training-helper-files/QT_Lab/lab4/style_sheet_tab.txt file
  11. voila ... TI colors - your setup should now match the look and feel of the one below:
    Sitara tabStyle.jpeg
  12. Run it!
  13. Extra investigation: Run a debug session and set break points in keyboard.cpp. Notice how the each QPushbutton signals the keyboardHandler slot.
    • NOTE

      If breakpoints are not working for you, verify you have created a Debug version of terminal and not a Release version. Look under Projects and "Build Settings" and check Details under Build Steps.

terminal style sheet settings

QWidget {
    background-color: rgb(0, 0, 0);

QTabWidget::pane {
    position: absolute;
    border: 2px solid red;

QTabWidget::tab-bar {
    alignment: center;

QTabBar::tab {
    color: red;
    background-color: black;
    border: 2px solid red;
    border-radius: 0px;
    padding: 4px;
    margin-left: 0.25em;
    margin-right: 0.25em;

QTabBar::tab:selected, QTabBar::tab:hover {
    color: white;
    background: red;

QPushButton {
     /**font: bold 16pt;
     color: white ;

     border-image: url(:/pushblueup.png);
     background-color: transparent;
     border-top: 3px transparent;
     border-bottom: 3px transparent;
     border-right: 10px transparent;
     border-left: 10px transparent;**/

tab style sheet settings

    background-color: red;

    background-color: black;
    color: yellow;

    background-color: white;
    color: black;


    background-color: white;

LAB 5: Exploring Existing Demos and Examples

Key Points

  • Exploring existing projects in the QT SDK.
  • Using a SGX accelerated QT Demo

Lab Steps

  1. In a console window on your host:
    • gedit /home/sitara/AM335x/ti-processor-sdk-linux-<machine>-<sdk version>/example-applications/matrix-gui-browser-2.0/main.cpp

      This is the QT application which displays matrix for all Sitara platforms. As you can see it uses a QWebView just like we did in the Terminal Enhancements Lab. The main differences are that you pass in the url as an argument, and all window framing was removed.
  2. Now try this one using the minicom connection to your target, it may surpise some of you:
    • cd usr/share/qt5/examples
    • We are now in the target Filesystem provided with Sitara SDK. Lets search for how many QT project files we can find.
      • find . -name *.pro
    • There are many QT project files here
      • find . -name *.pro | wc
    • Over 300 different projects already available in the SDK.
  3. Lets take a look at one specific example hellogl2. This is an SGX accelerate QT demo. In your minicom window do
    • cd /usr/share/qt5/examples/opengl/hellogl2
    • run this ./hellogl2
  4. You should see an SGX accelerated demo
  5. As mentioned there are many demos available. Some may not work due to how QT was configured when it was built.
  6. Some additional demo of interest:
    1. /usr/share/qt5/examples/webkitwidgets/browser -- This is the broswer demo featured in matrix.
  7. Extra Excercise: Pull in one the the demos or examples into QT Creator by opening it as a project. Build it and run it on the target.

    You may need need to do some project setup to make sure you will run on the target

Debugging QT Libraries

For debugging QT application with source code to QT libraries, corresponding QT library will need to be installed to the <ti-processor-sdk-linux-xxx>/linux-devkit/sysroots/armv7ahf-neon-linux-gnueabi location. The *.ipk package can be found from the yocto build of PSDK under build/arago-tmp-external-linaro-toolchain/work/armv7ahf-neon-linux-gnueabi. Linux "find" command can be used to refine the search for *.ipk file. For example, following steps to debug qtbase application

1. Copy and install the associated ipk packages into the sysroot directory

  1. dpkg -x qtbase-dbg_xxx_armv7ahf-neon.ipk sysroots/armv7ahf-neon-linux-gnueabi/

2. Set sysroot in the QT Creator: Under Tools -> Options -> Debugger tab of the QT Creator, go to the GDB tab and add these additional startup commands, for example set sysroot /home/sitara/ti-processor-sdk-linux-xxx/linux-devkit/sysroots/armv7ahf-neon-linux-gnueabi set debug-file-directory /home/sitara/ti-processor-sdk-linux-xxx/linux-devkit/sysroots/armv7ahf-neon-linux-gnueabi/usr/lib/.debug