Getting started

Before you start porting, ensure that all the prerequisites for Qt Quick Ultralite are met. This guide uses CMake in all the examples as Qt Quick Ultralite depends on the CMake build system.

This guide uses a dummy platform, example-baremetal, as an example for the porting steps. You can create your platform port based on this dummy platform or create one from scratch.

Setting up a Qt Quick Ultralite platform port project

Qt Quick Ultralite has all its supported platforms under platform directory. All platforms are under the boards subdirectory, where they are categorized based on the platform manufacturer's name. For example, the example-baremetal platform port's manufacturer is qt and the port can be found from platform\boards\qt\example-baremetal.

The existence of a platform is checked in platform\CMakeLists.txt by checking whether a directory for that platform exists:

if(BOARD_MANUFACTURER_NAME) # This case is for all platforms that have a manufacturer eg. ST, NXP
elseif((NOT QUL_PLATFORM_LOWERCASE STREQUAL "boards") AND EXISTS ${CMAKE_CURRENT_LIST_DIR}/${QUL_PLATFORM_LOWERCASE}) # This case is for platforms without manufacturer eg. 'qt'
    message(FATAL_ERROR "Following QUL_PLATFORM: ${QUL_PLATFORM} is not supported!")

BOARD_MANUFACTURER_NAME is a variable that is set by _qul_find_and_get_board_manufacturer_name macro. It is used to search for the given platform from the boards directory and return the directory where the specified port for the board resides.

To make your platform visible to Qt Quick Ultralite's CMake scripts, create a new directory for the platform:


Where <MANUFACTURER_NAME> and <YOUR_PLATFORM> can be named however you want.

You must add a CMakeLists.txt file for both the <MANUFACTURER_NAME> and the <YOUR_PLATFORM> directories. The CMakeLists.txt under <YOUR_PLATFORM> is configured in Creating the configuration file for you platform. The one under <MANUFACTURER_NAME> must contain at least the following:

string(TOLOWER ${QUL_PLATFORM} board_name)

You can also copy the contents of the example-baremetal platform to use as a reference.

Note: While all supported platforms have either baremetal or freertos appended to their names, the platform need not have either of them in its name.

Project structure

Qt Quick Ultralite does not have a strict structure that you have to follow. However, some things must be present and configured for the platform to be able to compile with Qt Quick Ultralite's CMake scripts.

cmake directory

Your project must have a cmake directory containing compiler and board information for Qt Quick Ultralite to be able to recognize and compile the platform. You may use the platform\boards\qt\example-baremetal\cmake directory as the basis for your platform's cmake directory. Note that example-baremetal project's cmake directory contains configuration for ARM GCC compiler only. If you are using a compiler other than ARM GCC or Green Hills Compiler, additional configuration is needed. For more information, see Using a custom toolchain.

The cmake directory has a following structure:

| | |-CompilationOptions.cmake
| | |-<YOUR_PLATFORM>.json
| | |-LinkerScriptLoader.cmake
| |-BoardDefaults.cmake
Defining default variables for the platform

BoardDefaults.cmake is used to set default variables for the platform port. For Qt Quick Ultralite, following variables can be set here:

QUL_COLOR_DEPTHHow many bits per pixel is used to render content. This variable is optional and does not do anything if not used in the code.
QUL_DEFAULT_SCREEN_WIDTHThe default screen width in pixels. Not setting this will result in an error.
QUL_DEFAULT_SCREEN_HEIGHTThe default screen height in pixels. Not setting this will result in an error.
OSOperating system that is used in the project, used by app_common. Currently only BareMetal and FreeRTOS values are recognized. If this value is not set, Qt Quick Ultralite defaults to BareMetal. If you do not use app_common, this variable has no effect.
EXCLUDED_EXAMPLESList of examples that are excluded from the build.

The following example disables freertos_multitask and redbutton examples:

    CACHE STRING "List of examples excluded from build")
EXCLUDED_DEMOSList of demos that are excluded from the build.

The following example disables automotive and motor_cluster demos:

    CACHE STRING "List of demos excluded from build")

Example BoardDefaults.cmake:


CompilationOptions.cmake contains compile and link options specific to your platform, such as architecture options and Qt Quick Ultralite specific compile definitions.

For Qt Quick Ultralite, the following definitions must be set in your project:

QUL_STATIC_NO_PRELOAD_ASSET_SEGMENTAssets that are loaded during the Qt Quick Ultralite application execution are added to this section of memory. The name of the section must be defined in the linker script.
QUL_STATIC_ASSET_SEGMENTAssets that are preloaded before the Qt Quick Ultralite application execution are added to this section of memory. The name of the section must be defined in the linker script.

These definitions require memory section names to be defined in the platform's linker script. See Linker script setup for instructions on how to setup a linker script for the Qt Quick Ultralite project.

For example, the CompilationOptions.cmake defines these options for the ARM GCC compiler:

    # Archtitecture specific compile definitions

    # Archtitecture specific compile options


    # Archtitecture specific link options
Creating the platform kit configuration file

<YOUR_PLATFORM>.json file is used to create a platform kit in the Qt Creator IDE.

Note: This file is required even if you are not going to use the Qt Creator IDE. If you are not using Qt Creator, you can leave this file empty.

Note: Custom compilers are not supported in Qt Creator.

The JSON file contains an object with values that are used by Qt Creator to create the kit:

qulVersionQt Quick Ultralite version the platform is built against. By default, this is set to @CMAKE_PROJECT_VERSION@.
platformName of the platform.
platformVendorName of the platform vendor/manufacturer.
colorDepthsList of supported color depths for the platform.
toolchainObject containing details of the toolchain the platform uses.
boardSdkObject containing details of the SDK the platform uses.

toolchain attribute contains the following information:

idName of the toolchain.
versionsList of toolchain versions that are supported.
cmakeToolchainFileLocation of the toolchain's CMake file.

boardSdk attribute contains the following information:

envVarEnvironment variable name pointing to the SDK used in Qt Quick Ultralite.
versionsList of SDK versions that are supported.

Here is an example JSON file (example-baremetal.json):

  "qulVersion": "@CMAKE_PROJECT_VERSION@",
  "platform": "EXAMPLE-BAREMETAL",
  "platformVendor": "VENDOR_NAME",
  "colorDepths": [
  "toolchain": {
    "id": "armgcc",
    "versions": [
    "cmakeToolchainFile": "lib/cmake/Qul/toolchain/armgcc.cmake"
  "boardSdk": {
    "versions": [
Adding your linker script

cmake\<YOUR_COMPILER>\<YOUR_LINKER_SCRIPT> is the linker script your platform uses. Qt Quick Ultralite uses the linker script to organize the data and code in the final binary to appropriate memory addresses. Setting up of the script is described in detail with an example in the Linker script setup section.

Adding your linker script to the project

LinkerScriptLoader.cmake is used by CMake to find the platform's linker script and how to use it in the compiler.

Here is how the LinkerScriptLoader.cmake looks for the example-baremetal platform:


LINKER_SCRIPT_OPTION is compiler defined and is set in toolchain CMake files. For more information, see Using a custom toolchain.

Creating the configuration file for you platform

platform\<YOUR_PLATFORM>\CMakeLists.txt is your platform's primary configuration file. It specifies all sources, include directories, compile definitions, and other parameters your platform requires. For more information about the CMake syntax, see CMake Documentation. You can also use platform\boards\qt\example-baremetal\CMakeLists.txt as a basis for your platform's CMakeLists.txt.

Note: When you are defining sources, include directories or other attributes for your platform, you must specify QuickUltralitePlatform as the target for these definitions.

The following is the CMakeLists.txt for the example-baremetal platform:

target_sources(QuickUltralitePlatform PRIVATE
    # Add platform source files here

target_include_directories(QuickUltralitePlatform PRIVATE
    # Add platform specific include directories here

target_compile_definitions(QuickUltralitePlatform PRIVATE
    # Insert platform specific compile flags here
    # e.g. APPLICATION_ADDRESS=0x90000000

The example CMakeLists.txt has two files defined in sources: platform.cpp and mem.cpp. These files contain sample code for basic functions and memory allocation API respectively. The contents of these files are documented in Implementing basic functions and Memory allocation in Qt Quick Ultralite platform abstraction chapters.

Creating flash targets

Qt Quick Ultralite CMake scripts offer support to generate targets for flashing binaries to the device. This is useful in the application development phase, where you might have to build and flash the binaries often. It offers a single command to build and flash the binary.

The following must be done in order to get flash targets generated:

  1. Create a new file called ExecutableHook.cmake under the platform\boards\<MANUFACTURER_NAME>\<YOUR_PLATFORM>\cmake directory.
  2. Add the following function to ExecutableHook.cmake:
    function(add_executable_hook name)
        add_custom_target("flash_${name}" COMMAND <COMMAND_FOR_YOUR_FLASHER>)
        message(STATUS "Added flash target flash_${name}")

    The name argument is the target application's name. For redbutton example, name would be redbutton and the resulting flash target is flash_redbutton. <COMMAND_FOR_YOUR_FLASHER> is the command you use to flash built binaries to the target device. Your binary can be found using $<TARGET_FILE_DIR:${name}>/${name}.elf. Depending on the compiler and the flashing tool, the generated binary might be in a format that is not ELF.

Running CMake for your platform should now output Added flash target flash_<EXAMPLE/DEMO>. If you've copied example-baremetal project, you can use the following command to test whether flashing runs your flasher correctly:

nmake flash_minimal

However, your platform is still quite barebones. If your build does not succeed, continue reading this guide and try again at a later time.

Linker script setup

Linker script is a file containing information about the platform's memory configuration. It also specifies regions where application code and data resides. The the linker script is used by the toolchain's linker to organize the data and code in the final binary at appropriate memory addresses. In this section, you will get to know what needs to be configured in your linker script to get Qt Quick Ultralite working.

Following examples are snippets from platform\boards\qt\example-baremetal\cmake\armgcc\example-platform.ld. You can copy this file to your project to use as a basis for your own linker script. However, it is recommended that you have your own linker script where you insert additional memory sections explained here.

Note: The examples use GNU linker script syntax. Some things may be implemented differently between different toolchain linker scripts. Refer your toolchain's manual for more information about the syntax for linker scripts.

In order to assign program sections to the device, its memory layout must be configured:

  FLASH (rx)               : ORIGIN = 0x08000000, LENGTH = 2048K /* internal flash */
  RAM (xrw)                : ORIGIN = 0x20000000, LENGTH = 512K /* internal sram */
  SDRAM (xrw)              : ORIGIN = 0xc0400000,  LENGTH = 8M /* external sdram memory */
  QSPI (rx)                : ORIGIN = 0x90000000, LENGTH = 64M /* external flash */

This layout has four regions: FLASH, RAM, SDRAM and QSPI. RAM and SDRAM both have execute, read, and write access. Whereas, FLASH and QSPI are read-only flash memories and thus have only read and execute access.

Note: Avoid using this layout as-is for your platform's memory layout, as it may lead to errors when flashing the binary or attempting to run it on the device. Refer your target platform's manual for the memory layout and appropriate memory addresses for your device.

To get asset separation in your project, Qt Quick Ultralite must know which memory sections are used for asset data:

    AssetDataPreload :
        . = ALIGN(4);
        _preloadable_assetdata_dst_begin = .;
        . = ALIGN(4);
        _preloadable_assetdata_dst_end = .;
    } > SDRAM AT > QSPI

    _preloadable_assetdata_src = LOADADDR(AssetDataPreload);

    AssetDataKeepInFlash :
        . = ALIGN(4);
    } > QSPI

In this example, both preloadable asset data and static asset data are kept in the QSPI flash memory region, but preloadable asset data section also reserves space from SDRAM. Both AssetDataPreload and AssetDataKeepInFlash names can be changed, but they must be consistent with names specified in platform\boards\<MANUFACTURER_NAME>\<YOUR_PLATFORM>\<YOUR_COMPILER>\CompilationOptions.cmake.

_preloadable_assetdata_dst_begin, _preloadable_assetdata_dst_end, and _preloadable_assetdata_src must also be defined. They are used in the platform code to load the assets from QSPI to SDRAM:

// Preloading assets
extern unsigned char _preloadable_assetdata_src;
extern unsigned char _preloadable_assetdata_dst_begin;
extern unsigned char _preloadable_assetdata_dst_end;

       &_preloadable_assetdata_dst_end - &_preloadable_assetdata_dst_begin);

Using a custom toolchain

By default, Qt Quick Ultralite supports ARM GCC or GHS toolchains across supported platforms. However, it is possible to use your own compiler in the project.

To configure Qt Quick Ultralite for your toolchain, follow these steps:

  1. Add a <YOUR_COMPILER>.cmake to lib\cmake\Qul\toolchain directory.
  2. Create <YOUR_COMPILER> directory under platform\boards\<MANUFACTURER_NAME>\<YOUR_PLATFORM>\cmake.
  3. Edit CMake configuration files in Qt Quick Ultralite

Adding <YOUR_COMPILER>.cmake to the project

Add the <YOUR_COMPILER>.cmake to the lib\cmake\Qul\toolchain directory. This file configures your toolchain for the project. You can also use existing toolchain configurations as a basis for your compiler configuration.

The following variables should be set in the file:

CMAKE_SYSTEM_NAMEThe operating system CMake is building for. This must be set to Generic.
CMAKE_SYSTEM_PROCESSORThe processor CMake is building for. For example, if your target CPU is ARM CPU, set this to arm.
COMPILER_FOLDER_NAMETells Qt Quick Ultralite project what compiler directory should be used for the target platform. This must match the name of the compiler directory in platform\boards\<MANUFACTURER_NAME>\<YOUR_PLATFORM>\cmake or else you will get errors during configuration.
LINKER_SCRIPT_OPTIONThis is used in LinkerScriptLoader.cmake to tell linker what flags to use. If you are not using LINKER_SCRIPT_OPTION, this is not needed.
CMAKE_C_COMPILERPath to the C compiler.
CMAKE_CXX_COMPILERPath to the C++ compiler.
CMAKE_ASM_COMPILERPath to the assembly compiler. This is not needed if you do not have assembly files in you platform.
CMAKE_ARPath to the toolchain's archiver.
CMAKE_CXX_FLAGS_INITC++ compiler flags that are used in every configuration.
CMAKE_C_FLAGS_INITC compiler flags that are used in every configuration.
CMAKE_C_FLAGS_DEBUGC compiler flags that are used in debug configuration in addition to the flags used in CMAKE_C_FLAGS_INIT.
CMAKE_CXX_FLAGS_DEBUGC++ compiler flags that are used in debug configuration in addition to the flags used in CMAKE_CXX_FLAGS_INIT.
CMAKE_EXE_LINKER_FLAGS_INITLinker flags that are used in every configuration.

In addition, you also need to set a variable that can be used to identify your compiler:


This is used in other CMake files to configure additional things if needed.

<YOUR_COMPILER> directory

Create a directory named <YOUR_COMPILER> (or the name you set to COMPILE_FOLDER_NAME in the previous step) for your toolchain in the platform\boards\<MANUFACTURER_NAME>\<YOUR_PLATFORM>\cmake directory, and add all required files mentioned in the "cmake directory" section.

CMake configuration files in Qt Quick Ultralite

Your toolchain may require some additional configuration in Qt Quick Ultralite.

The following files contain compiler-dependent configurations and might be worth checking out.

  • examples\CMakeLists.txt has compiler-dependent warning flags, such as Wall and Werror. If your compiler does not support already provided flags, add your own here.
  • platform\CMakeLists.txt If you are going to use same compiler on multiple platforms, it might be a good idea to write some common compilation options for QuickUltralitePlatform here.
  • src\CMakeLists.txt is used to build QuickUltralite target. If your compiler has some specific arguments that must be taken into account, add them here.

    The file also includes configuration code for supported compilers. Check that your compiler can use the set parameters and modify the code if needed.

  • src\pngdecoders.cmake adds LodePNG based PNG decoder to Qt Quick Ultralite. If your compiler has some specific arguments that must be taken into account when building the decoder, add them here.

Your compiler setup is ready to be used now. Test it by running CMake with -DCMAKE_TOOLCHAIN_FILE=path\to\Qt\QtMCUs\1.5.0\cmake\Qul\toolchain\<YOUR_COMPILER>.cmake.

Available under certain Qt licenses.
Find out more.