Known Issues or Limitations
The following is a list of known issues in Qt for MCUs dev. For workarounds or information about the status of these issues, contact Qt Support.
To view all user-reported issues, visit the Qt for MCUs public bug tracker.
- Development host environment support is limited to Windows 10 and Ubuntu 20.04.
- Qt Quick Ultralite is a subset of Qt Quick and as such does not provide all the base and control QML types, which are available on the non-MCU platforms. Refer to Qt Quick Ultralite vs Qt Quick and Differences between Qt Quick Ultralite Controls and Qt Quick Controls for more information.
- EventQueue::postEvent is not interrupt safe.
- The Text type does not properly render unicode sequences that require complex text layout. Use StaticText for complex text.
- SequentialAnimation and ParallelAnimation do not start automatically when assigned to a property using the "on" syntax. Explicitly set the running property to
trueto start the animation.
Item::visiblechanges the visibility of child items but does not update the
visibleproperty of those items.
- font.pointSize does not respect screen DPI. Recommend using font.pixelSize instead.
- The default state has some limitations. Refer to Default state limitations for more information.
- States where multiple PropertyChanges or AnchorChanges target anchor properties on the same item will not work as expected. Use a single PropertyChanges instead.
- Setting anchors to undefined does not restore previous position and size bindings.
- A RotationAnimation in a transition may apply to non-rotation properties. Use PropertyAnimation::properties instead.
- All delegates in a ListView must have the same size. The size must be explicitly specified and cannot be dynamically changed.
onPropertyChangedis not supported for grouped properties.
transformOriginproperties are only generated if they have bindings. For example, if an
scaleis not explicitly declared with an initial value, setting
item.scale = 2results in a compilation error. This can be resolved by adding the
scale: 1binding to the item.
- Bindings on color value accessors are not supported.
- Using the clip property on transformed items is not supported.
- Transforms on an item do not apply to the item's children. Individually set transforms on each child instead.
- RGB332 pixel format is not supported by any of the reference boards. It can be only used for the desktop backend or custom hardware.
- Font property bindings are supported only when using the Spark font engine. See Text Rendering and Fonts for details.
- When editing Qt Quick Ultralite QML files, the following errors are displayed in the Issues panel and highlighted in the code editor. They can safely be ignored:
- package import requires a version number
A version number can optionally be added but is not strictly required in Qt Quick Ultralite.
- Unknown component for
Set the QML_IMPORT_PATH variable in your CMake project file to the location of the QUL compatibility module to solve this issue.
- package import requires a version number
- QML debugging is not supported
- QML profiling is not supported
- On-device preview is not supported. To preview the design on your MCU board, use the auto-generated CMake project and compile it using Qt Creator.
- Qt Quick Ultralite-specific QML types (
ColorizedImage) are not available in the component library.
The following is a list of known issues on the Renesas RH850 hardware.
- The internal ROM is used to store code (data and text) and the graphical assets only. This limits the size of the executable to be not more than 5 MB.
- Qt Quick Ultralite dev does not enter low CPU power mode. If no frame is rendered and no other tasks are running, Qt Quick Ultralite loops until next frame needs to be rendered or another task needs CPU time.
- The Monotype Spark font engine (Technology Preview) is not supported.
The following is a list of known issues on the STM32H750B hardware.
- Screen may flicker while performing double precision operations. For that reason, qreal defaults to
- The SDK version 1.6.0 is not supported yet.
The following is a list of known issues on the NXP i.MXRT1050 hardware.
- When debugging, interrupted program won't resume its execution and must be restarted by using the
mon reset haltcommand.
- To work around a GNU Arm Embedded Toolchain bug (https://bugs.launchpad.net/gcc-arm-embedded/+bug/1747966), all the object files and libraries are passed to
ldin a linker group (using
--end-group). Additionally, libraries are passed to linker before application object files, which is opposite to default behavior.
- Microsoft Visual C++ Compiler (MSVC++) v14.29 (Visual Studio 2019 Version 16.9) or newer is not supported. Supported versions are v14.16 up to v14.28.
- Building Qt Quick Ultralite application as a static library is not supported on FreeRTOS.
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