Problems when adding serialport module in Qt project

[douglas]

@aha_1980 how I can upgrade to the latest Qt version and set it as default in my project? After this I will be sure to use the Qt version 5.9 and I will apply the steps suggested by @Pablo-J-Rogina
Thank you!

[aha_1980]

@douglas

First you should find out which Qt versions you have on your computer. Qt 4.8.7 is surely from Ubuntu and is a native Qt - you build programs that run on your computer. What you want, is a cross Qt, to run programs on your embedded device.

As you said you have already done this, you surely have a second Qt version (I cannot tell you which one it is). And this Qt version has a qmake which you need to call to compile Qt programs against this Qt library.

Regards

[douglas]

@aha_1980 Thanks. In Qt Creator I set Qt 5.7.1 in the "Qt Version" for the selected kit for my project. Now I can add the serialport module in my .pro file and build the app, but when I try to run it on my target device, the application does not start and the following error appears:

error while loading shared libraries: libQt5SerialPort.so.5: cannot open shared object file: No such file or directory

Is it related to the serialport module that is not cross compiled or have I to install some dependencies on the target device itself?
Thank you!

[aha_1980]

@douglas said in Problems when adding serialport module in Qt project:

Is it related to the serialport module that is not cross compiled or have I to install some dependencies on the target device itself?

You're already on the right track. You need to cross-compile QtSerialPort for your embedded device, and then you need to deploy (copy over) these libraries to the device, because your final app is also running there.

[douglas]

@aha_1980 Ok,thanks! I just did the following on my host PC:

$ git clone git://code.qt.io/qt/qtserialport.git
$ mkdir qtserialport-build
$ cd qtserialport-build
$ qmake ../qtserialport/qtserialport.pro

but the last command (qmake) gives the following:

Project MESSAGE: Cannot build current QtSerialPort sources with Qt version 4.8.7.
Project ERROR: Use at least Qt 5.0.0 or try to download QtSerialPort for Qt4.

It is clear that I need to use a newer qmake, perhaps the default one is an older version. How can I run that command with a qmake version 5? Where should it be located? Or how can I "change the default one"?
Thanks for your patience.

[douglas]

@aha_1980 Done, I found the qmake for version 5 and run the qmake command.
Now, when I run the

make
make install

this error appears:

fatal error: qdeadlinetimer.h: File o directory non esistente
compilation terminated.

Which can be the solution?

[aha_1980]

@douglas you are tryin to compile a new QSerialPort against an older Qt.

Add a git checkout -b v5.7.1 directly after the git clone command and rebuild.

[douglas]

@aha_1980 I add "git checkout -b v5.7.1" , but the qdeadlinetimer.h error shown above still remains during the make procedure. Any hints?

[jsulm]

@douglas Did you try to delete the build folder, create new one and to start from there?

[douglas]

@jsulm Yes, I did. I always obtain the

fatal error: qdeadlinetimer.h: File o directory non esistente
compilation terminated.

[aha_1980]

@douglas please send the output of git status

[douglas]

@aha_1980

Sul branch v5.7.1
Untracked files:
  (use "git add <file>..." to include in what will be committed)

	./

nothing added to commit but untracked files present (use "git add" to track)

Am I missing something?

[aha_1980]

@douglas Looks good so far.

But let's move slowly. I re-read you post from 5 hours ago:

@aha_1980 Thanks. In Qt Creator I set Qt 5.7.1 in the "Qt Version" for the selected kit for my project. Now I can add the serialport module in my .pro file and build the app

If you can build the app, then you already have the serialport module!

but when I try to run it on my target device, the application does not start and the following error appears:

But you don't have the libraries on your target device.

[douglas]

@aha_1980 Thanks, I understand. In order to obtain those libraries on my target device is something that I should copy from my host PC onto the device itself or I should install directly on the device side in any way?

[aha_1980]

@douglas In the most easy and hacky way, just copy the needed *.so files to the other Qt *.so files on your device.

Depending on your cross toolchain, there may be a more clean way (like building a new image), but that - as said - depends on you toolchain.

[Pablo J. Rogina]

@douglas as @aha_1980 said, maybe easiest way is to copy the serialport module *.so the same way you're deploying the file(s) for your application. Perhaps at the beginning it's easy to copy the shared library into same folder as application's executable

[douglas]

@Pablo-J.-Rogina , @aha_1980 thank you. I expected to find the libQt5SerialPort.so.5 (the missing library) inside the qtserialport folder generated after the steps:

$ git clone git://code.qt.io/qt/qtserialport.git
$ mkdir qtserialport-build
$ cd qtserialport-build
$ qmake ../qtserialport/qtserialport.pro

but I couldn't find it. I searched into my host PC for that file, I found few results, but they are located into the Qt installation folder, they are not cross-compiled for my needs, I think.
When exactly that library should be created, or where it should be located?
Thanks!

[jsulm]

@douglas Are you sure you're cross compiling your app?
If so just do

ldd YOUR_APP_EXE

it will show you which libs it is linked against, you then will know where the serial port lib is.

[douglas]

@jsulm the ldd command does not give any result; it gives a message saying it is "not a dynamic exacutable"..

[douglas]

Solved. The missing libQt5SerialPort.so.5 error on the target device was because that library effectively was not present. On the host side I added that library in the package list of the image and rebuild the image itself.