Cannot Connect to QML Emulation Layer (QML Puppet)



  • I'm runnin QT Creator 3.2.1 based on Qt 5.3.2. My Compiler is GCC 4.9.2 and I'm running Qt on a Raspberry with Raspbian Jessy installed.
    I'm pretty new to Raspberry and to Qt. Qt is pretty slow on my Raspberry but I didn't want to cross-compile so I chose to design my GUI on the Raspberry itself.
    When I start s new Widget Project and go into Designer-Mode everthing goes well. But when I start a Qt Quick Application I get following error message when starting the Designer:

    Cannot connect to QML Emulation Layer (QML Puppet)
    The executable of the QML emulation layer (QML Puppet) may not be responding. Switching to another kit might help.
    

    I tried switching to another kit. The default kit has a desktop as device type and local PC as device.
    When I switch the device type to generic linux device I cant select a device.
    I also tried to disbale the "Always use the QML emulation layer provided by QT Creator" under Options/QT Qucik/QT Quick Designer

    So far nothing worked any help would be much obliged



  • Some people reported that they solved similar issues with reinstalling Qt. Also, this is an issue that was already reported in the bugtracker.

    Still, my guess is that you're better if off if you take the time to set up your environment for cross-compilation. You can do that with the help of the Buildroot Project as described in our blog!

    edit: this might be helpful as well: https://github.com/pbouda/buildroot-qt-dev



  • Thanks a lot Lorenz. I installed Qt on my Laptop with ubuntu. I also installed buildroot but I have two questions:

    1. Do I need to set up buildroot on my Raspberry or on my Laptop?
    2. When I look up guides for how to configure buildroot for the Raspberry people change all kind of things I have no clue about. How do I know if the settings are also optimal for me (most refer to differnet Raspberrys or older Versions of buildroot)?

    I use these two guides:
    https://www.raspberrypi.org/forums/viewtopic.php?f=75&t=89518
    https://www.youtube.com/watch?v=key9SkCU3io
    which also differ from each other.

    Thanks for any help



  • Wouldn't it be easier to follow these instrudctions?
    Cross Compilling Qt5 for the Pi



  • Hi Millo,

    Indeed your link looks fine as well! Just go with what you're more comfortable with I'd say.

    1 - Buildroot goes on your laptop. QtCreator goes on your laptop as well, here's a tutorial to set it up:
    https://github.com/pbouda/buildroot-qt-dev/blob/master/doc/qtcreator.md

    2 - I would follow (only) the steps in this github https://github.com/pbouda/buildroot-qt-dev/blob/master/doc/qtcreator.md

    It's been a while since we did some testing on our Raspberry, and we were successful with Buildroot, but unfortunately I can not recall all the details :)

    Good Luck!
    Lorenz



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  • @Lorenz said in Cannot Connect to QML Emulation Layer (QML Puppet):
    .com/pbouda/buildroot-qt-dev/blob/master/doc/qtcreator.md

    2 - I would follow (only) the steps in this github https://github.com/pbouda/buildroot-qt-dev/blob/master/doc/qtcreator.md

    It's been a while since we did some testing on our Raspberry, and we were successful with Buildroot, but unfortunately I can not recall all the details :)

    Good Luck!
    Lorenz

    Im sorry Lorenzo but this guide doesn't work. I'm stuck at this part:

    Warning: Your SD card has to prepared with the two Raspberry partitions. If you do not edit the script  installrootfs.sh  with the correct device names your hard disk might get formatted!
    
    You can now run the script. The script expects the path to the SD Card device and the path to the root file system image and the kernel as the first argument. Buildroot puts those in the folder  output/images . So change directory into  scripts  and run  installrootfs.sh  with the absolute path to your  buildroot-2015.05/output/images  folder:
    $ cd ../scripts/
    $ ./installrootfs.sh /dev/sdX /path/to/buildroot-qt-dev/buildroot-2015.05/output/images
    
    

    I install the raspberry image as advised. If I insert the SD card into my Pi everything works fine. Then I run the installrootfs.sh. When I instert the SD card now he asks me to login which I can successfully do but after that almost no commands work. The shell always tells me unknown command, even when typing sudo, apt-get or other things. Commands like ls or reboot do work tho. Also the GUI wont load.
    Do you know what to do differently? Im also confused because in teh first paragraph it says to edit the script which shouldnt be neccessary if I run the script with the right arguments?


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