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.

BOARD_MANUFACTURER_NAME is a variable that is set by qul_private_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:

mkdir platform/boards/<MANUFACTURER_NAME>/<YOUR_PLATFORM>

md platform\boards\<MANUFACTURER_NAME>\<YOUR_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 your platform. The one under <MANUFACTURER_NAME> must contain at least the following:

include(CMakeDependentOption)
string(TOLOWER ${QUL_PLATFORM} board_name)
add_subdirectory(${CMAKE_CURRENT_LIST_DIR}/${board_name})

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

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 and IAR compiler. If you are using a compiler other than ARM GCC, Green Hills, or IAR compilers, additional configuration is needed. For more information, see Using a custom toolchain.

The cmake directory has a following structure:

<YOUR_PLATFORM>
|-cmake
| |-<YOUR_COMPILER>
| | |-platform.cmake
| | |-<YOUR_PLATFORM>.json
| | |-<YOUR_LINKER_SCRIPT>
| |-BoardArchitectureConfig.cmake
| |-BoardDefaults.qmlprojectconfig
| |-BSPConfig.cmake
| |-LinkerScriptConfig.cmake

Defining default variables for the platform

Since Qt for MCUs 2.3, BoardDefaults.cmake file is removed, changing the platform file structure. All information in this file is organized in following way:

• BoardDefaults.qmlprojectconfig contains Qt Quick Ultralite engine-specific configurations the target board.
• BoardArchitectureConfig.cmake contains information about the platform architecture.
• LinkerScriptConfig.cmake contains linker script configurations. See Adding your linker script to the project
• Platform-specific configurations were moved to the platform CMakeLists.txt file. See Setting platform properties

See QmlProject Manual for more information.

BoardDefaults.qmlprojectconfig naming scheme

A platform port can have more than one BoardDefaults.qmlprojectconfig files depending on different board or display configurations. To be able to support all those configurations, use the following naming convention:

BoardDefaults_<color_depth>bpp_<default>.qmlprojectconfig

where:

• The color_depth should be value set to the QUL_COLOR_DEPTH CMake variable. This value is used also to determine the span of available configurations based on multiple qmlprojectconfig files existing in the platform cmake directory.
• If there are multiple configurations, use the default keyword for one of them to indicate a default configuration.

The following table describes different example scenarios and the corresponding configuration file name:

cmake
|- BoardDefaults.qmlprojectconfig

cmake
|- BoardDefaults_32bpp.qmlprojectconfig

cmake
|- BoardDefaults_8bpp.qmlprojectconfig
|- BoardDefaults_16bpp.qmlprojectconfig
|- BoardDefaults_32bpp.qmlprojectconfig

cmake
|- BoardDefaults_8bpp_default.qmlprojectconfig
|- BoardDefaults_16bpp.qmlprojectconfig
|- BoardDefaults_32bpp.qmlprojectconfig

Setting platform properties

Since Qt for MCUs 2.3 platform related configurations are set in the target platform CMakeLists.txt file as the Platform target properties. List of the all properties with default values and descriptions are presented in following table:

Common properties:

set_target_properties(Platform
    PROPERTIES
        QUL_PLATFORM_EXCLUDED_EXAMPLES "freertos_multitask;image_cache"
)

set_target_properties(Platform
    PROPERTIES
        QUL_PLATFORM_EXCLUDED_DEMOS "automotive;motor_cluster"
)

set_target_properties(Platform
    PROPERTIES
        QUL_PLATFORM_EXCLUDED_TESTS "controls;flickable"
)

Cypress platform-specific properties:

NXP platform-specific properties:

STM platform-specific properties:

Example properties set in platform CMakeLists.txt:

set_target_properties(Platform
    PROPERTIES
        NXP_CHIP_NAME "MIMXRT1052xxxxB"
        NXP_CONNECT_SCRIPT "RT1050_connect.scp"
        # variables cannot be expanded that's why there is "\" before "$". It will be later evaluated at CMake runtime using
        # qul_private_evaluate_path_from_target_property() function
        NXP_PARTFILES_DIR "\${QUL_PLATFORM_TARGET_DIR}/../mimxrt1050-evk-common/cmake"
        QUL_PLATFORM_EXCLUDED_DEMOS "automotive;motor_cluster"
        QUL_PLATFORM_EXCLUDED_EXAMPLES "freertos_app_switch;layers;multiscreen;shapes"
        QUL_PLATFORM_EXCLUDED_TESTS "layers;layer_transparency;pathstroke;resource_storage_section"
        QUL_PRIVATE_USE_PLATFORM_CONFIGURATION_HEADER ON
    EXPORT_PROPERTIES "NXP_CHIP_NAME;NXP_CONNECT_SCRIPT;NXP_PARTFILES_DIR;QUL_PLATFORM_EXCLUDED_DEMOS;QUL_PLATFORM_EXCLUDED_EXAMPLES;QUL_PLATFORM_EXCLUDED_TESTS"
)

Specifying compile and link options for the platform

platform.cmake contains compile and link options specific to your platform. Architecture options can be found in the files for the specific architecture.

Specifying vendor SDK specific settings

BSPConfig.cmake contains all settings that are required for using functions from the vendor SDK, like GPIO or interrupt handlers.

See Platform SDK Config.

These usually are defines for a specific board and include paths.

target_compile_definitions(PlatformBSPConfig INTERFACE
    # Platform SDK specific compile definitions
    USE_HAL_DRIVER
)

target_include_directories(PlatformBSPConfig INTERFACE
    # Platform SDK specific include directories
    # eg. ${QUL_BOARD_SDK_DIR}/Drivers/BSP/STM32F769I-Discovery/
)

Creating the platform kit configuration file

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

Main elements of the kit's JSON file are:

The JSON file contains a collection of json objects used by Qt Creator to create the kit. Each object represents a 3rd party dependency (package) and holds a path to the dependency. The path will later be forwarded to different outputs:

• A cmake variable used to configure the project (e.g. -DFREERTOS_DIR=<path>)
• A directory that will be added to PATH environment variable

The package value can be read by QtCreator from the folowing locations, in order:

• Qt Creator settings.
• The correspoding Environmental variable (envVar).
• The defaultValue defined in the json file.

In summary the packages required for a correct kit to be generated are:

• Platform's 3rd party packages (cmakeEntries array).
• The toolchain packages (a compiler and a toolchain file).
• BoardSdk package
• FreeRTOS package (when applicable)

Each package has the following attributes:

The platform json kit file can be validated using a schema file found in $QUL_ROOT/kits/schemas/ and a jsonschema validation tool of choice, an online solution can be found here. The schemas are using the Draft-2020-12 specification. Currently only "schema-2.3" is provided to validate kits that works with QtMCUs 2.3.0 and higher.

Main elements of the kit's JSON file are: Here is an example JSON file (example-baremetal.json):

{
    "qulVersion": "@CMAKE_PROJECT_VERSION@",
    "compatVersion": "@COMPATIBILITY_VERSION@",
    "platform": {
        "colorDepths": [
            16
        ],
        "id": "EXAMPLE-BAREMETAL",
        "vendor": "Vendor Name"
    },
    "toolchain": {
        "id": "armgcc",
        "versions": [
            "10.3.1"
        ],
        "compiler": {
            "id": "ARMGCC_DIR",
            "label": "GNU Arm Embedded Toolchain",
            "cmakeVar": "QUL_TARGET_TOOLCHAIN_DIR",
            "envVar": "ARMGCC_DIR",
            "setting": "GNUArmEmbeddedToolchain",
            "type": "path",
            "optional": false,
            "versionDetection": {
                "filePattern": {
                    "windows": "bin/arm-none-eabi-g++.exe",
                    "linux": "bin/arm-none-eabi-g++"
                },
                "executableArgs": "--version",
                "regex": "\\b(\\d+\\.\\d+\\.\\d+)\\b"
            },
            "detectionPath": {
                "windows": "bin/arm-none-eabi-g++.exe",
                "linux": "bin/arm-none-eabi-g++"
            }
        },
        "file": {
            "id": "ARMGCC_CMAKE_TOOLCHAIN_FILE",
            "cmakeVar": "CMAKE_TOOLCHAIN_FILE",
            "type": "file",
            "defaultValue": "%{Qul_ROOT}//lib/cmake/Qul/toolchain/armgcc.cmake",
            "visible": false,
            "optional": false
        }
    },
    "boardSdk": {
        "versions": [
            "1.16.0"
        ],
        "id": "EXAMPLE_SDK_DIR",
        "label": "Board SDK",
        "cmakeVar": "QUL_BOARD_SDK_DIR",
        "type": "path",
        "optional": false
    }
}

Here is the JSON file for the IAR compiler. It has a few differences compared to the previous example:

{
    "qulVersion": "@CMAKE_PROJECT_VERSION@",
    "compatVersion": "@COMPATIBILITY_VERSION@",
    "platform": {
        "id": "EXAMPLE-BAREMETAL",
        "vendor": "Vendor Name",
        "colorDepths": [
            16
        ]
    },
    "toolchain": {
        "id": "iar",
        "versions": [
            "9.20.4"
        ],
        "compiler": {
            "id": "IARToolchain",
            "setting": "IARToolchain",
            "envVar": "IAR_ARM_COMPILER_DIR",
            "label": "IAR ARM Compiler",
            "cmakeVar": "QUL_TARGET_TOOLCHAIN_DIR",
            "type": "path",
            "versionDetection": {
                "filePattern": {
                    "windows": "bin/iccarm.exe",
                    "linux": "bin/iccarm"
                },
                "executableArgs": "--version",
                "regex": "\\bV(\\d+\\.\\d+\\.\\d+)\\.\\d+\\b"
            },
            "detectionPath": {
                "windows": "bin/iccarm.exe",
                "linux": "bin/iccarm"
            },
            "defaultValue": {
                "windows": "%{Env:PROGRAMFILES}/IAR Systems/Embedded Workbench 9.0/arm",
                "linux": "/opt/iarsystems/bxarm-9.20.4/arm"
            },
            "optional": false
        },
        "file": {
            "id": "IAR_CMAKE_TOOLCHAIN_FILE",
            "cmakeVar": "CMAKE_TOOLCHAIN_FILE",
            "type": "file",
            "defaultValue": "%{Qul_ROOT}/lib/cmake/Qul/toolchain/iar.cmake",
            "visible": false,
            "optional": false
        }
    },
    "boardSdk": {
        "versions": [
            "1.16.0"
        ],
        "id": "EXAMPLE_SDK_DIR",
        "label": "Board SDK",
        "cmakeVar": "QUL_BOARD_SDK_DIR",
        "type": "path",
        "optional": false
    }
}

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

A default linker script can be set in LinkerScriptConfig.cmake to be used by CMake. example-baremetal platform:

if(IAR)
    qul_platform_add_default_linker_script("${QUL_PRIVATE_PLATFORM_BOARD_CMAKE_DIR}/${QUL_COMPILER_NAME}/example-platform.icf")
else()
    qul_platform_add_default_linker_script("${QUL_PRIVATE_PLATFORM_BOARD_CMAKE_DIR}/${QUL_COMPILER_NAME}/example-platform.ld")
endif()

The argument defines the linker script to use. For more information, see Using a custom toolchain.

Creating the configuration file for your 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.

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

target_sources(Platform PRIVATE
    examplelayerengine.cpp
    examplepath.cpp
    examplestroker.cpp
    examplequeue.cpp
    platform_context.cpp
    devicelink.cpp
    mem.cpp
    ${PLATFORM_COMMON_SRC_DIR}/singlepointtoucheventdispatcher.cpp
    ${PLATFORM_COMMON_SRC_DIR}/platform.cpp
    # Add platform source files here
)

target_include_directories(Platform PRIVATE
    # Add platform specific include directories here
)

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

For IAR compiler, use the following example as a reference:

target_sources(Platform PRIVATE
    examplelayerengine.cpp
    examplepath.cpp
    examplestroker.cpp
    examplequeue.cpp
    platform_context.cpp
    devicelink.cpp
    mem-iar.cpp
    ${PLATFORM_COMMON_SRC_DIR}/singlepointtoucheventdispatcher.cpp
    ${PLATFORM_COMMON_SRC_DIR}/platform.cpp
    # Add platform source files here
)

target_include_directories(Platform PRIVATE
    # Add platform specific include directories here
)

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

The example CMakeLists.txt has two files defined in sources: platform_context.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}")
   endfunction()

   The name argument is the target application's name. For minimal example, name would be minimal and the resulting flash target is flash_minimal. <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 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. There is also a variant for IAR linkers available at platform\boards\qt\example-baremetal\cmake\iar\example-platform.icf for your reference. You can copy these files 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.

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

MEMORY
{
  FLASH (rx)               : ORIGIN = 0x08000000, LENGTH = 2048K /* internal flash */
  RAM (xrw)                : ORIGIN = 0x20000000, LENGTH = 512K /* internal sram */
  SDRAM (xrw)              : ORIGIN = 0xc0400000, LENGTH = 6M /* external sdram memory */
  SDRAM_PRELOAD (xrw)      : ORIGIN = 0xc0a00000, LENGTH = 2M /* external sdram memory - preload */
  QSPI (rx)                : ORIGIN = 0x90000000, LENGTH = 64M /* external flash */
}

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

In this example resource data is stored in the QSPI flash memory region. QulResourceData name is hardcoded and represents the default section for the image resources. For adding additional resource sections see Managing Resources.

QulFontResourceData name is hardcoded and represents the default section for the font files and glyph data. Custom font files section is configured with MCU.Config.fontFilesStorageSection property and glyphs section with MCU.Config.glyphsStorageSection.

The QulModuleResourceData section is reserved by Qt Quick Ultralite to place its internal resources. User-specified resources should not be placed in it.

    QulFontResourceData :
    {
        . = ALIGN(4);
        *(QulFontResourceData)
    } > QSPI

    QulModuleResourceData :
    {
        . = ALIGN(4);
        __ModuleResourceDataCacheStart = .;
        *(QulModuleResourceData)
        . = ALIGN(4);
        __ModuleResourceDataCacheEnd = .;
    } > SDRAM AT> QSPI

    __ModuleResourceDataStart = LOADADDR(QulModuleResourceData);

    QulResourceData :
    {
        . = ALIGN(4);
        *(QulResourceData)
    } > QSPI

This example reserves space from the SDRAM for the preloadable resources with SDRAM_PRELOAD region. Symbols __preloadSdramStart and __preloadSdramEnd are defined for the resource preloading to determine the start and end address of the preload section:

    __preloadSdramStart = ORIGIN(SDRAM_PRELOAD);
    __preloadSdramEnd = ORIGIN(SDRAM_PRELOAD) + LENGTH(SDRAM_PRELOAD);

Example platform adaptation creates pointers to the linker symbols:

extern uint8_t __preloadSdramStart;
extern uint8_t __preloadSdramEnd;
void *preloadSdramStart = &__preloadSdramStart;
void *preloadSdramEnd = &__preloadSdramEnd;

By default the resources use DefaultPreload allocation type. Preload start and end address are used by the ExampleReversePreloadAllocator to determine the maximum size of the preload section.

PlatformInterface::MemoryAllocator *ExamplePlatform::memoryAllocator(
    PlatformInterface::MemoryAllocator::AllocationType type)
{
    static ExampleMemoryAllocator exampleMemoryAllocator;
    static ExampleReversePreloadAllocator<4> examplePreloadAllocator(preloadSdramEnd, preloadSdramStart);
    static PlatformInterface::MemoryAllocator defaultMemoryAllocator;

    switch (type) {
    case PlatformInterface::MemoryAllocator::Image:
        return &exampleMemoryAllocator;
    case PlatformInterface::MemoryAllocator::DefaultPreload:
        return &examplePreloadAllocator;
    default:
        return &defaultMemoryAllocator;
    }
}

Preloading can be disabled by returning nullptr from the memory allocator for the DefaultPreload allocation type.

Preloading Qt Quick Ultralite internal resources

Qt Quick Ultralite internal resources contain the image data for example for the dials and buttons that are linked to the application from Qul::Controls library. Internal resources do not support preloading with Qul::PlatformInterface::MemoryAllocator.

In this example preloadable internal resource data is copied from the QSPI flash memory region to SDRAM.

__ModuleResourceDataCacheStart, __ModuleResourceDataCacheEnd, and __ModuleResourceDataStart must also be defined. They are used in the platform code to load the resources from QSPI to SDRAM:

extern unsigned char __ModuleResourceDataStart;
extern unsigned char __ModuleResourceDataCacheStart;
extern unsigned char __ModuleResourceDataCacheEnd;
memcpy(&__ModuleResourceDataCacheStart,
       &__ModuleResourceDataStart,
       &__ModuleResourceDataCacheEnd - &__ModuleResourceDataCacheStart);

For IAR compilers there need to be some section declarations included

#pragma section = "QulModuleResourceData"
#pragma section = "QulModuleResourceData_init"
char *__ModuleResourceDataStart = (char *) (__section_begin("QulModuleResourceData_init"));
char *__ModuleResourceDataCacheStart = (char *) (__section_begin("QulModuleResourceData"));
char *__ModuleResourceDataCacheEnd = (char *) (__section_end("QulModuleResourceData"));
memcpy(__ModuleResourceDataCacheStart,
       __ModuleResourceDataStart,
       (unsigned) __ModuleResourceDataCacheEnd - (unsigned) __ModuleResourceDataCacheStart);

Make sure to check the example IAR linker script to see how to place these sections in your device memory.

Using a custom toolchain

By default, Qt Quick Ultralite supports ARM GCC, GHS, or IAR toolchains across the 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:

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

SET(<YOUR_COMPILER> ON)

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 Platform here.
• src\CMakeLists.txt is used to build Core 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.