Webinar On-Demand: Qt on Raspberry Pi

Questions & Answers from Live Webinar

Q - Why there is no prebuilt Qt packages for RPI, why we should always compile it from source?
A - Unfortunately, no one has stepped forward as a maintainer of Qt 5 for Raspbian Linux, so the version of Qt in Raspbian is quite old and at the moment the best solution is to build it yourself from source. Also, different users have different requirements (e.g. desktop versus embedded) that might require Qt to be built differently. Hopefully in the future someone (maybe ICS) will offer up to date, tested, Qt packages for the Raspberry Pi.

Q - I see in your slides "boot2qt" is a custom OS for Qt apps?
A - Yes, boot2qt is a customized version of Yocto embedded Linux from The Qt Company that supports a number of embedded boards including the Raspberry Pi. See http://doc.qt.io/QtForDeviceCreation/qtee-about-b2qt.html for more details.

Q - What about Qt on the Windows 10 Iot in RPI platform?
A - Windows 10 IoT Core is aimed at headless embedded systems with no display, so Qt would be of limited use. It might be possible to build QtCore on it for non-graphical applications. I am not aware of anyone having tried it.

Q - Do we require any special type of building method to enable hardware acceleration to run good fps opengl apps?
A - Generally, no. Your application should use the hardware OpenGL unless you somehow misconfigure it. You may want to adjust the amount of RAM which is allocated to the GPU (using the raspi_config program).

Q - What license is Qt for developing on rPI?
A - The same as on other platforms - it is available under a number of licenses, see https://www.qt.io/licensing/

Q - Why do we always need to compile Qt from sources, why is there no prebuilt Qt5 packages?
A - See the earlier answer to this question.

Q - OpenSource vs Commercial license?
A - You can use Qt under an Open Source or commercial license. You need to comply with the requirements. See https://www1qt.io/licensing/

Q - Is there any support from ICS or Qt in making and maintaining prebuilts?
A - ICS can offer paid support and consulting for this. The Qt Company will provide support if you purchase commercial licenses for Qt.

Q - Can QtCreator remote debug to the RaspPi?
A - Yes, the same as on other Linux platforms if you have an ssh network connection to the Raspberry Pi.

Q - Can an RS485 connection be supported?
A - There is no RS-485 hardware on board. If you had a USB RS-485 adaptor that was supported under Linux, I expect that you could use Qt's QSerialPort class to control it.

Q - Will Qt5 + QML applications run well on Pi 1 B+ or it requires Pi3?
A - If it is not CPU-intensive and the screen resolution is not too high, the graphics performance of a Rasperry Pi 1 is not too bad in my experience.

Q - Is QSerialPort supported?
A - Yes, if you use a USB to Serial converter. There is a serial interface on the GPIO connector that should work as well, but it is not a full RS-232 interface.

Q - Hi, you briefly mentioned Wayland compositing, can you expand a bit on that? What can you use it for on the raspberry pi?
A - Essentially it allows multiple applications to run using OpenGL/ES as the back end rendered. There is a good article here: https://en.wikipedia.org/wiki/Wayland_(display_server_protocol)

Q - What are the steps to start programming with Qt on R Pi?
A - I would say the same as Qt on any other platform. You can start by reading the documentation, build some examples, and then try making some code changes yourself.

Q - Is there a pre-compiled packages or repository for Qt5? PySide or PyQt?
A - No, see the earlier question. For now you would need to build it from source.

Q - What USB version is supported?
A - The ports are USB 2.0.

Q - Is the Pi Zero W processor 32 bit?
A - Yes. While the Pi 3 is 64-bit, but currently runs in 32-bit mode.

Q - Is the Pi zero W suitable for running a basic Qt GUI program? or would you recommend a Pi 3?
A - It will work for small programs, but a Pi 3 will be faster.

Q - Hardware OpenGL (without Wayland) requires the app to be full screen?
A - Yes, if you use the eglfs back end for Qt. You could use the xcb (X11) back and and use Qt's OpenGL classes and then still run under the X11 window manager (not full screen).

Q - Can the Qt SerialPort module work on Raspberry Pi ?
A - Yes, see earlier question.