Problems when adding serialport module in Qt project

douglas

@Pablo-J.-Rogina Thanks a lot for your post, I'll now begin to put it into practice. I have just one doubt: if I run:

qmake --version

I obtain:

QMake version 2.01a
Using Qt version 4.8.7 in /usr/lib/x86_64-linux-gnu

So, if I'm not wrong, the installed version of Qt is the 4.8.7 (quite old). When you stated, in your #1 step, "git clone git://code.qt.io/qt/qtserialport.git -b 5.9" were you assuming my Qt version was 5.9? In other words, the serialport version and the installed qt version should be the same?
If so, how can I upgrade from my actual Qt version to the latest one?
Thanks a lot!

aha_1980

@douglas

you can have multiple Qt versions installed, so please check carefully which one you use.

For the qmakes that are not in PATH, you have to specify the full path, e.g. /opt/Qt/5.9.0/bin/qmake

Regards

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.