Qt first project

[mrjj]

@nick784512
In that video, he mere set the text he gets to a QLabel
MainWindow::serialReceived .
If it should respond to anything you must program it yourself.

Please show what you changed it into to reply ? :)

[nick784512]

$$$$$$$$$$$$$$$serialGui.pro$$$$$$$$$$$$$$$$$$

#-------------------------------------------------

Project created by QtCreator 2016-12-06T15:42:10

#-------------------------------------------------

QT += core gui serialport

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = serialGui
TEMPLATE = app

SOURCES += main.cpp
mainwindow.cpp

HEADERS += mainwindow.h

FORMS += mainwindow.ui

$$$$$$$$$$$$$$$$$$mainwindow.h$$$$$$$$$$$$$$$$$$$$$$$$$

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private slots:
void serialReceived();

private:
Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

$$$$$$$$$$$$$$$$$$$$main.cpp$$$$$$$$$$$$$$$$$$$$$$$$$$$

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}

$$$$$$$$$$$$$$$$$$$mainwindow.cpp$$$$$$$$$$$$$$$$$$$$$$$

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtSerialPort>
#include <QDebug>

QSerialPort *serial;

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
serial = new QSerialPort(this);
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->setParity(QSerialPort::NoParity);
serial->setStopBits(QSerialPort::OneStop);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->open(QIODevice::ReadWrite);
serial->write("hello");
serial->close();
connect(serial,SIGNAL(readyRead()),this,SLOT(serialReceived()));
}

MainWindow::~MainWindow()
{
delete ui;
serial->close();
}

void MainWindow::serialReceived()
{
QByteArray ba;
ba=serial->readAll();
ui->label->setText(ba);
qDebug()<<ba;
}

$$$$$$$$$$$$$$$$mainwindow.ui$$$$$$$$$$$$$$$$$$$$$$$$$

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>400</width>
<height>300</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralWidget">
<widget class="QLabel" name="label">
<property name="geometry">
<rect>
<x>50</x>
<y>60</y>
<width>121</width>
<height>41</height>
</rect>
</property>
<property name="text">
<string>TextLabel</string>
</property>
</widget>
</widget>
<widget class="QMenuBar" name="menuBar">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>400</width>
<height>21</height>
</rect>
</property>
</widget>
<widget class="QToolBar" name="mainToolBar">
<attribute name="toolBarArea">
<enum>TopToolBarArea</enum>
</attribute>
<attribute name="toolBarBreak">
<bool>false</bool>
</attribute>
</widget>
<widget class="QStatusBar" name="statusBar"/>
</widget>
<layoutdefault spacing="6" margin="11"/>
<resources/>
<connections/>
</ui>

[SGaist]

Why are you closing your serial port in the constructor ? You won't receive anything doing so.

[nick784512]

@SGaist

I disabled it. Again, nothing received.

[SGaist]

You also don't check whether open was successful.

You should rather move the call to write outside the constructor. e.g. in a slot connected to a push button.

And make serial a member of MainWindow.

[nick784512]

Thank you! I cannot understand how the tutorial video in youtube works and the same configuration and coding in my project does not work.

[SGaist]

Did you check that the settings of the serial ports are really what you need to use with your device ?

[nick784512]

@SGaist

1)How do I check if the serial opened succefully?
2)I disabled write.
3)Do you mean to make it private member of MainWindow?

[SGaist]

1. Please read the documentation, the open function returns a boolean value saying whether it succeeded or not
2. Where did you put the call to write ?
3. Yes

[nick784512]

@SGaist

1)Ok, I will try it.
2)I just commented it.
3) I wrote QSerialPort *serial; under private and it shows error

[SGaist]

What error ?

If you comment the call to write then don't expect anything particular to happen.

[nick784512]

@SGaist

C:\Users\geo\Documents\serialGui\mainwindow.h:27: error: 'QSerialPort' does not name a type
QSerialPort *serial;
^

I don't want to write something in COM from Qt, I want to "listen" from Arduino the sequence 232323... and print on the Qt application

[SGaist]

It's nothing Qt related, that's basic C++. You really should grab a good book on the matter.

Search for "Forward declaration".

[nick784512]

I know C, not C++. Are they so different?

[SGaist]

There are some key concepts that are pretty different yes.

[nick784512]

And I should learn C++ for just this little error?

Can someone help me to make it work?

[nick784512]

$$$$$$$$$$$$$$$$$$$$$serialGui.pro$$$$$$$$$$$$$$$$$$$$$$$$$$

#-------------------------------------------------

Project created by QtCreator 2016-12-06T15:42:10

#-------------------------------------------------

QT += core gui serialport

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = serialGui
TEMPLATE = app

SOURCES += main.cpp
mainwindow.cpp

HEADERS += mainwindow.h

FORMS += mainwindow.ui

$$$$$$$$$$$$$$$$$ mainwindow.h $$$$$$$$$$$$$$$$$$$$$$$$$$

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private slots:
void serialReceived();

void on_pushButton_released();

private:
Ui::MainWindow *ui;

QSerialPort *serial;

};

#endif // MAINWINDOW_H

$$$$$$$$$$$$$$$ main.cpp $$$$$$$$$$$$$$$$$$$$$$$$$

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}

$$$$$$$$$$$$$$$$$$$$$$ mainwindow.cpp $$$$$$$$$$$$$$$$$$$$$$$$

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtSerialPort>
#include <QDebug>

QSerialPort *serial;

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
if (serial->open(QIODevice::ReadWrite))
{
ui->setupUi(this);
serial = new QSerialPort(this);
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->setParity(QSerialPort::NoParity);
serial->setStopBits(QSerialPort::OneStop);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->open(QIODevice::ReadWrite);
//serial->write("hello");
serial->close();
connect(serial,SIGNAL(readyRead()),this,SLOT(serialReceived()));
}
else
{
QMessageBox::critical(this, tr("Error"), serial->errorString());
showStatusMessage(tr("Open error"));
}
}

MainWindow::~MainWindow()
{
delete ui;
serial->close();
}

void MainWindow::serialReceived()
{
QByteArray ba;
ba=serial->readAll();
ui->label->setText(ba);
//qDebug()<<ba;
}

$$$$$$$$$$$$$$$$$$$ mainwindow.ui $$$$$$$$$$$$$$$$$$$$$$$$$$

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>400</width>
<height>300</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralWidget">
<widget class="QLabel" name="label">
<property name="geometry">
<rect>
<x>50</x>
<y>60</y>
<width>121</width>
<height>41</height>
</rect>
</property>
<property name="text">
<string>TextLabel</string>
</property>
</widget>
</widget>
<widget class="QMenuBar" name="menuBar">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>400</width>
<height>21</height>
</rect>
</property>
</widget>
<widget class="QToolBar" name="mainToolBar">
<attribute name="toolBarArea">
<enum>TopToolBarArea</enum>
</attribute>
<attribute name="toolBarBreak">
<bool>false</bool>
</attribute>
</widget>
<widget class="QStatusBar" name="statusBar"/>
</widget>
<layoutdefault spacing="6" margin="11"/>
<resources/>
<connections/>
</ui>

[JKSH]

@nick784512 said in Qt first project:

And I should learn C++ for just this little error?

You should learn C++ to use a C++ toolkit.

It feels like a "little error" now, but you will encounter this in most (if not all) of your C++ projects.

Can someone help me to make it work?

@SGaist already gave you the answer: You need to add a Forward Declaration for QSerialPort in mainwindow.h.

Also remember to #include <QSerialPort> in mainwindow.cpp

[nick784512]

Hello!

I managed to make it work and send symbols over the serial. The problem now is that when I send from the arduino (to Qt application) 2 or 3 symbols it prints them OK! But when I want to send the sentence "Hello World!" it breaks it into pieces and prints them, as you can see in the photo.

http://www.picpaste.com/pics/serial_problem-V7LlwzUC.1483458098.jpg

(Can the moderator attach the photo to this message?)

[SGaist]

That' why you usually have a protocol to know when you received all the data that are part of a "frame" and only then parse them for further processing.