QextSerialPort with QTimer approch for reading

[PaceyIV]

Hi,

I try to emit a signal with the data actually received by QextSerialPort: something like the event DataReceived of C# .NET.

When I open the port I start a QTimer that every 100ms checks if there is byte available on the port and emit the signal with the data read.

My GUI freezes in this way If I block the sender device, my GUI exits from the freeze state and show some data.

Any ideas?

serialport.h

#include <QObject>
class QextSerialPort;
class QTimer;
 
class SerialPort : public QObject
{
    Q_OBJECT
 
public:
    SerialPort(QObject *parent = 0);
    ~SerialPort();
 
signals:
    void receivedBytes(const QByteArray&, int);
 
public slots:
    bool openPort();
    void closePort();
 
private slots:
    void checkRx();
 
private:
    QextSerialPort *d_port;
    QTimer  *d_timer;
};

#include <QObject>
class QextSerialPort;
class QTimer;

class SerialPort : public QObject
{
    Q_OBJECT

public:
    SerialPort(QObject *parent = 0);
    ~SerialPort();

signals:
    void receivedBytes(const QByteArray&, int);

public slots:
    bool openPort();
    void closePort();

private slots:
    void checkRx();

private:
    QextSerialPort *d_port;
    QTimer  *d_timer;
};

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serialport.cpp

#include <QTimer>
#include <QDebug>
#include <qextserialport.h>
#include "serialport.h"
 
const int timeout = 100;
 
SerialPort::SerialPort(QObject *parent):
        QObject(parent)
{
    //modify the port settings on your own
    d_port = new QextSerialPort("/dev/ttyUSB0");
    d_port->setBaudRate(BAUD19200);
    d_port->setFlowControl(FLOW_OFF);
    d_port->setParity(PAR_NONE);
    d_port->setDataBits(DATA_8);
    d_port->setStopBits(STOP_1);
 
    d_timer = NULL;
}
 
SerialPort::~SerialPort()
{
    d_port->close();
    delete d_port;
    d_port = NULL;
 
    d_timer->stop();
    delete d_timer;
    d_timer = NULL;
}
 
bool SerialPort::openPort()
{
    bool state;
    state = d_port->open(QIODevice::ReadWrite);
 
    if (state)
    {
        if ( !d_timer )
        {
            d_timer = new QTimer(this);
            connect(d_timer, SIGNAL(timeout()),
                    this, SLOT(checkRx()));
        }
        d_timer->start(timeout);
    }
    return state;
}
 
void SerialPort::closePort()
{
    if (d_timer)
        d_timer->stop();
 
    d_port->close();
}
 
void SerialPort::checkRx()
{
    int numBytes;
 
    numBytes = d_port->bytesAvailable();
 
    if (numBytes>0)
    {
        qDebug() << numBytes;
 
        numBytes = (numBytes > 1024) ? 1024 : numBytes;
 
        QByteArray bytes = d_port->read(numBytes);
 
        emit receivedBytes(bytes, numBytes);
    }
}

#include <QTimer>
#include <QDebug>
#include <qextserialport.h>
#include "serialport.h"

const int timeout = 100;

SerialPort::SerialPort(QObject *parent):
        QObject(parent)
{
    //modify the port settings on your own
    d_port = new QextSerialPort("/dev/ttyUSB0");
    d_port->setBaudRate(BAUD19200);
    d_port->setFlowControl(FLOW_OFF);
    d_port->setParity(PAR_NONE);
    d_port->setDataBits(DATA_8);
    d_port->setStopBits(STOP_1);

    d_timer = NULL;
}

SerialPort::~SerialPort()
{
    d_port->close();
    delete d_port;
    d_port = NULL;

    d_timer->stop();
    delete d_timer;
    d_timer = NULL;
}

bool SerialPort::openPort()
{
    bool state;
    state = d_port->open(QIODevice::ReadWrite);

    if (state)
    {
        if ( !d_timer )
        {
            d_timer = new QTimer(this);
            connect(d_timer, SIGNAL(timeout()),
                    this, SLOT(checkRx()));
        }
        d_timer->start(timeout);
    }
    return state;
}

void SerialPort::closePort()
{
    if (d_timer)
        d_timer->stop();

    d_port->close();
}

void SerialPort::checkRx()
{
    int numBytes;

    numBytes = d_port->bytesAvailable();

    if (numBytes>0)
    {
        qDebug() << numBytes;

        numBytes = (numBytes > 1024) ? 1024 : numBytes;

        QByteArray bytes = d_port->read(numBytes);

        emit receivedBytes(bytes, numBytes);
    }
}

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[PaceyIV]

I solved my problem by using 2 QThread instead of the QTimer.
Now I use my class MySerialPort with a thread for sending operation and another thread for receiving operation with the emission of the signal DataReceived like .NET.