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QSerialPort::readyRead() emiting not working?



  • Im trying to figure out if its because of QSerialPort bug (but was fixed in 5.13.2 and im on 5.14.0 rc2).

    led.h:

    #ifndef LED_H
    #define LED_H
    
    #include <QObject>
    #include <QSerialPort>
    #include <QCoreApplication>
    
    class LED : public QObject
    {
        Q_OBJECT
    
    public:
        explicit LED(QObject *parent = nullptr);
        Q_INVOKABLE void setColor(int red, int green, int blue);
    
    public slots:
    
    private:
        QSerialPort m_serial;
        void readReply();
    
    signals:
    
    };
    
    #endif // LED_H
    

    led.cpp:

    #include <QtDebug>
    #include "led.h"
    #include <windows.h>
    #include <QSerialPort>
    #include <QSerialPortInfo>
    #include <fileapi.h>
    #include <QDataStream>
    #include <QtSerialPort/QSerialPort>
    #include <QCoreApplication>
    
    QString m_port = "COM3";
    
    LED::LED(QObject *parent) :
        QObject(parent)
    {
        connect(&m_serial, &QSerialPort::readyRead, this, &LED::readReply);
    }
    
    void LED::readReply()
    {
        const QByteArray receivedData = m_serial.readAll();
        qDebug() << "Received:" << receivedData;
    }
    
    void LED::setColor(int red, int green, int blue)
    {
        QByteArray writeData;
        writeData.resize(15);
    	// some noniportant staff populating writeData
    
        m_serial.setPortName(m_port);
    
        if (!m_serial.open(QIODevice::ReadWrite)) {
            qDebug() << "Can not open the" << m_port << "port:" << m_serial.errorString() << "//" << m_serial.error();
            m_serial.close();
            return;
        }
        if (!m_serial.setBaudRate(QSerialPort::Baud9600)) {
            qDebug() << "Could not set baud rate to 9600, remaining value is" << m_serial.baudRate();
            m_serial.close();
            return;
        }
        if (!m_serial.setDataBits(QSerialPort::Data8)) {
            qDebug() << "Could not set data bits number, remaining value is" << m_serial.dataBits();
            m_serial.close();
            return;
        }
        if (!m_serial.setParity(QSerialPort::NoParity)) {
            qDebug() << "Could not set parity check option, remaining value is" << m_serial.parity();
            m_serial.close();
            return;
        }
        if (!m_serial.setStopBits(QSerialPort::OneStop)) {
            qDebug() << "Could not set stop bits, remaining value is" << m_serial.stopBits();
            m_serial.close();
            return;
        }
    
        m_serial.write(writeData);
        m_serial.waitForBytesWritten(1500);     // max timeout 1000ms, set -1 to wait up to 30s
        qDebug() << "Sending:" << writeData;
    
        m_serial.close();
        return;
    }
    

    first of all, writing to the COM port works fine... its a LED screen and when I write() it changes color, so I can see it works fine... also the qDebug() << "Sending:" << writeData worksfine…

    however, I have no responce whatsoever in my debug log...

    what do I do wrong?


  • Moderators

    @shokarta I'm pretty sure, your port has to remain open, for it to emit readyRead


  • Moderators

    @shokarta I'm pretty sure, your port has to remain open, for it to emit readyRead


  • Lifetime Qt Champion

    @shokarta said in QSerialPort::readyRead() emiting not working?:

    m_serial.waitForBytesWritten(1500);

    Don't use waitFor... in programs that also use Signals&Slots.

    Regards


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