Qt first project

nick784512

What this http://doc.qt.io/qt-5/qtserialport-terminal-settingsdialog-cpp.html code does?
From C language I know that we have to also call a function. Where are the functions called?

SGaist

The dialog is shown when clicking on the configure button in main dialog.

Then when you click on the connect button, the openSerialPort method will retrieve the current setting for the serial port and update the serial member variable properties with the settings from the dialog.

nick784512

Thank you. Now that I want to make the simple project as I said before. How many files do I need?

mainwindow.h
mainwindow.cpp
main.cpp
mainwindow.ui

are all these enough?

SGaist

Based on your requirements, you only need a QWidget, a QPushButton and a QVBoxLayout to put the button nicely in the widget.

nick784512

But where will I put the code?

SGaist

In your QWidget subclass.

nick784512

In main.cpp?

jsulm

@nick784512 I would suggest you to create a simple widgets application and play a bit with it. You will see how Qt widgets applications are usually implemented. See http://doc.qt.io/qtcreator/creator-writing-program.html
Asking others to send you an implementation is not really the right way to learn. Best is "learning by doing" and asking specific questions if you're stuck.

nick784512

I have tried this one: https://www.youtube.com/watch?v=UD78xyKbrfk
and I connected the arduino to the COM3 with a program that sends 2 3 2 3... but the Qt program does not display the 2 3 2 3 ....

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

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