[SOLVED] QSerialPort Crash when i click button or close application

matijalazic

Hello,
So I have been working in Qt for quite a long time now. But until last week I was only working with developing simple console applications. I also like to have fun with electronic devices and stuff. So i made an electronic device which connects to PC over Arduino UNO. I need to read data with C++ GUI program. I have looked at a lot of examples and did exactly the same but my program keeps crashing when I click the button. Button is supposed to connect to Serial port COM3. But it crashes. I have been looking for a solution for the last 3 hours so I wouldnt waste your time with questions already answered (I did howsoever find something about crashing after program closes). I really appreciate all your responses.

Screenshot:
!http://shrani.si/f/3o/Xv/f2Y2jOc/trest.png(picture)!

MainWindow.h
@#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

#include <QtCore/QCoreApplication>
#include <QtCore/QDebug>

#include <QtSerialPort/QSerialPort>
#include <QtSerialPort/QSerialPortInfo>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
void set_label_2_text(QString tekst);
void set_label_text(QString tekst);
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private slots:
void readData();
void on_pushButton_clicked();

private:
bool conn;
QSerialPort *serial;
Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
@

MainWindow.cpp
@#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QtCore/QCoreApplication>
#include <QtCore/QDebug>

#include <QtSerialPort/QSerialPort>
#include <QtSerialPort/QSerialPortInfo>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);

conn = false;

connect(serial, SIGNAL(readyRead()), this, SLOT(readData()));

}

void MainWindow::set_label_text(QString tekst)
{
QFont f( "Arial", 12);
ui->label->setFont(f);
ui->label->setText(tekst);
}
void MainWindow::set_label_2_text(QString tekst)
{
ui->label_2->setText(tekst);
}

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

void MainWindow::readData()
{
if(conn == true) {
QByteArray data = serial->readAll();
ui->label_2->setText((QString) data);
}
}

void MainWindow::on_pushButton_clicked()
{
serial->setPortName("COM3");
serial->setBaudRate(QSerialPort::Baud9600);
serial->setDataBits(QSerialPort::Data8);
serial->setFlowControl(QSerialPort::NoFlowControl);
serial->setParity(QSerialPort::NoParity);
serial->setStopBits(QSerialPort::OneStop);
if(serial->open(QIODevice::ReadWrite))
conn = true;
/*foreach (const QSerialPortInfo &info, QSerialPortInfo::availablePorts()) {
qDebug() << "Name : " << info.portName();
qDebug() << "Description : " << info.description();
qDebug() << "Manufacturer: " << info.manufacturer();

        if(info.description() == "USB-SERIAL CH340") {
            set_label_text("CONNECTED! on " + info.portName());

            serial->setPort(info);
            serial->open(QIODevice::ReadWrite);
            connect(serial, SIGNAL(readyRead()), this, SLOT(readData()));
        }
    }*/

}
@

t3685

What object is your "serial" pointing to?

tomasz3dk

You didn't instantiate serialport, add:
@serial = new QSerialPort(this);@

into MainWindow constructor.

matijalazic

THANK YOU!! That was the issue. I expected it would be just a little mistake which are easiest to miss... Really thank you it works flawlessly now. Im gonna hide in my shame corner for missing such obvious thing :D