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  4. Is data received from serial port possible to view on two forms?
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Is data received from serial port possible to view on two forms?

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  • S Shivam Sharma

    Ok. So, I have received the data from the serial port and it displays on the gui in a text box. For now attached a GPS sensor and hence i get the GPRMC string very well. Now i also want the same string to be displayed on my form2.

    But writing the same code doesn't help. As in, in form 2 all I've changed is QSerialPort *serial1; that's it.

    Here is the code:

    QSerialPort *serial;
    QString line;
    QString txt1;
    MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
    {
    ui->setupUi(this);
    serial = new QSerialPort(this);
    serial = new QSerialPort(this);
    serial->setPortName("ttyUSB0");
    serial->setBaudRate(QSerialPort::Baud9600);
    serial->setDataBits(QSerialPort::Data8);
    serial->setParity(QSerialPort::NoParity);
    serial->setStopBits(QSerialPort::OneStop);
    serial->setFlowControl(QSerialPort::NoFlowControl);

       if( serial->open(QIODevice::ReadWrite))
        {
            qDebug()<<"Port Open OK";
            connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
        }
      else
        {
            qDebug()<<"Can't Open Port : " << serial->error();
        }
       serialReceived();
    

    }

    void Setup::serialReceived()
    {
    QByteArray serialData;
    serialData = serial1->readAll();

    char t0[512];
    static char t1[512];
    static int wp=0;
    unsigned int i=0;
    
    QString filename="/home/user/Desktop/Programs/MainCBOT2/dataentry2.txt";
    QFile file( filename );
    
    if(file.open(QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text))
    {
        QTextStream stream( &file );
        strcpy(t0,serialData);
        for (i=0;i<strlen(t0);i++)
        {
            t1[wp++]=t0[i];
            wp%=512;
            t1[wp]=0;
    
            if(t0[i] == '\n')
            {
                wp=0;
                if(checksum_gps1(t1))
                {
                    if(memcmp("$GPRMC",t1,6)==0)
                    {
                        ui->receiver->append(t1);
                    }
                }
            }
        }
        file.close();
    }
    

    }

    JonBJ Online
    JonBJ Online
    JonB
    wrote on last edited by
    #4

    @Shivam-Sharma
    In your code the only mention of serial1 is in serialData = serial1->readAll();. So obviously that's an undeclared variable. C++ absolute basics. No idea what you expect.

    1 Reply Last reply
    0
    • S Shivam Sharma

      Ok. So, I have received the data from the serial port and it displays on the gui in a text box. For now attached a GPS sensor and hence i get the GPRMC string very well. Now i also want the same string to be displayed on my form2.

      But writing the same code doesn't help. As in, in form 2 all I've changed is QSerialPort *serial1; that's it.

      Here is the code:

      QSerialPort *serial;
      QString line;
      QString txt1;
      MainWindow::MainWindow(QWidget *parent)
      : QMainWindow(parent)
      , ui(new Ui::MainWindow)
      {
      ui->setupUi(this);
      serial = new QSerialPort(this);
      serial = new QSerialPort(this);
      serial->setPortName("ttyUSB0");
      serial->setBaudRate(QSerialPort::Baud9600);
      serial->setDataBits(QSerialPort::Data8);
      serial->setParity(QSerialPort::NoParity);
      serial->setStopBits(QSerialPort::OneStop);
      serial->setFlowControl(QSerialPort::NoFlowControl);

         if( serial->open(QIODevice::ReadWrite))
          {
              qDebug()<<"Port Open OK";
              connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
          }
        else
          {
              qDebug()<<"Can't Open Port : " << serial->error();
          }
         serialReceived();
      

      }

      void Setup::serialReceived()
      {
      QByteArray serialData;
      serialData = serial1->readAll();

      char t0[512];
      static char t1[512];
      static int wp=0;
      unsigned int i=0;
      
      QString filename="/home/user/Desktop/Programs/MainCBOT2/dataentry2.txt";
      QFile file( filename );
      
      if(file.open(QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text))
      {
          QTextStream stream( &file );
          strcpy(t0,serialData);
          for (i=0;i<strlen(t0);i++)
          {
              t1[wp++]=t0[i];
              wp%=512;
              t1[wp]=0;
      
              if(t0[i] == '\n')
              {
                  wp=0;
                  if(checksum_gps1(t1))
                  {
                      if(memcmp("$GPRMC",t1,6)==0)
                      {
                          ui->receiver->append(t1);
                      }
                  }
              }
          }
          file.close();
      }
      

      }

      J.HilkJ Online
      J.HilkJ Online
      J.Hilk
      Moderators
      wrote on last edited by
      #5

      @Shivam-Sharma

      ok, first of:

      You can't open the same serial port twice. The OS will not allow it. SO simply copying the whole serial port implementation to get the same signal again is the worst way to do it ;)

      I suggest the following:
      inside MainWindo, define a signal

      signals:
            void newSerialData(QString data);
      

      and emit it where you also set it to your UI form

      inside setup do this slot:

      public slots:
           void onNewSerialData(QString data);
      //.cpp
      void Setup::onNewSerialData(QString data)
      {
           ui->receiver->append(data);
      }
      

      than connect the signal to the slot (where you create the 2nd window)

      connect(this, &MainWindow:: newSerialData, my2ndForm, &Setup:: onNewSerialData);
      

      I would have been more specific on where to write what, but you only posted excerpts of your actual code 🤷‍♂️


      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


      Q: What's that?
      A: It's blue light.
      Q: What does it do?
      A: It turns blue.

      S 1 Reply Last reply
      4
      • J.HilkJ J.Hilk

        @Shivam-Sharma

        ok, first of:

        You can't open the same serial port twice. The OS will not allow it. SO simply copying the whole serial port implementation to get the same signal again is the worst way to do it ;)

        I suggest the following:
        inside MainWindo, define a signal

        signals:
              void newSerialData(QString data);
        

        and emit it where you also set it to your UI form

        inside setup do this slot:

        public slots:
             void onNewSerialData(QString data);
        //.cpp
        void Setup::onNewSerialData(QString data)
        {
             ui->receiver->append(data);
        }
        

        than connect the signal to the slot (where you create the 2nd window)

        connect(this, &MainWindow:: newSerialData, my2ndForm, &Setup:: onNewSerialData);
        

        I would have been more specific on where to write what, but you only posted excerpts of your actual code 🤷‍♂️

        S Offline
        S Offline
        Shivam Sharma
        wrote on last edited by J.Hilk
        #6

        @J-Hilk Hey yeah, i guess excerpts are pretty vauge. I am getting what you want to convey but just not being able to do some silly issue. Pasting the entire code below,

        //Mainwindow.h
        
        #ifndef MAINWINDOW_H
        #define MAINWINDOW_H
        
        #include <QMainWindow>
        #include <info.h>
        #include <setup.h>
        
        QT_BEGIN_NAMESPACE
        namespace Ui { class MainWindow; }
        QT_END_NAMESPACE
        
        class MainWindow : public QMainWindow
        {
            Q_OBJECT
        
        public:
            MainWindow(QWidget *parent = nullptr);
            ~MainWindow();
            Info *info;
            Setup *setup;
        
        signals:
            void newSerialData(QString data);
        
        private slots:
            void serialReceived();
            void on_infobutton_clicked();
            void on_setupbutton_clicked();
        
        private:
            Ui::MainWindow *ui;
        
        };
        #endif // MAINWINDOW_H
        
        //Mainwindow.cpp
        
        #include "mainwindow.h"
        #include "ui_mainwindow.h"
        #include <info.h>
        #include <setup.h>
        
        #include <QList>
        #include <QComboBox>
        #include <QString>
        #include <QTextEdit>
        #include <QTime>
        #include <QDebug>
        #include <QSerialPort>
        #include <QtSerialPort/QSerialPortInfo>
        #include <QFile>
        #include <qmath.h>
        #include <QList>
        
        QSerialPort *serial;
        QString line;
        QString txt1;
        MainWindow::MainWindow(QWidget *parent)
            : QMainWindow(parent)
            , ui(new Ui::MainWindow)
        {
               ui->setupUi(this);
               serial = new QSerialPort(this);
               serial = new QSerialPort(this);
               serial->setPortName("ttyUSB0");
               serial->setBaudRate(QSerialPort::Baud9600);
               serial->setDataBits(QSerialPort::Data8);
               serial->setParity(QSerialPort::NoParity);
               serial->setStopBits(QSerialPort::OneStop);
               serial->setFlowControl(QSerialPort::NoFlowControl);
        
               if( serial->open(QIODevice::ReadWrite))
                {
                    qDebug()<<"Port Open OK";
                    connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
                }
              else
                {
                    qDebug()<<"Can't Open Port : " << serial->error();
                }
               serialReceived();
        }
        
        MainWindow::~MainWindow()
        {
            delete ui;
            serial->close();
        }
        
        char *get_field(char *str,int fld)
        {
            static char t0[512];
            int i=0,j=0,k=0;
            while(i<512)
            {
                if(*(str+i) == ',' || *(str+i) == '\n')
                {
                    if (fld==j) return t0;
                        j++;
                        t0[0]=0;
                        k=0;
                }
                else
                {
                    t0[k++]=*(str+i);
                    t0[k]=0;
                }
                i++;
            }
                t0[0]=0;
                return t0;
        }
        
        int checksum_gps(char *str)
        {
            unsigned char cs=0,sum=0,i=0;
            char sCS[8], exit =0;
        
            while (i<250 && !exit)
            {
                if(*(str+i) == '*')
                {
                    sum=0;
                    break;
                }
                if(sum)
                    cs^=*(str+i);
                if(*(str+i) == '$')
                    sum=1;
                if(*(str+i) == 0)
                    exit=1;
                i++;
            }
            sprintf(sCS,"%02X",cs);
            if (memcmp(sCS,str+i+1,2)==0)
                return 1;
            return 0;
        }
        
        char *timestamp(void)
        {
            static char t0[128];
            long ms;
            time_t now;
            struct tm *t;
            struct timespec spec;
        
            time(&now);
            t= localtime(&now);
            clock_gettime(CLOCK_REALTIME, &spec);
            ms= round(spec.tv_nsec/1.0e6);
        
            sprintf(t0, "%04d/%02d/%02d %02d:%02d:%02d.%03ld ",
                    t->tm_year+1900, t->tm_mon+1, t->tm_mday,
                    t->tm_hour, t->tm_min, t->tm_sec, ms);
            return t0;
        }
        
        void MainWindow::serialReceived()
        {
            QByteArray serialData;
            serialData = serial->readAll();
            QString static receivedData = QString::fromStdString(serialData.toStdString());
        
            char t0[512];
            static char t1[512];
            static int wp=0;
            unsigned int i=0;
        
            QString filename="/home/user/Desktop/Programs/MainCBOT2/entrydata.txt";
            QFile file( filename );
        
            if(file.open(QIODevice::WriteOnly | QIODevice::Append | QIODevice::Text))
            {
                QTextStream stream( &file );
                strcpy(t0,serialData);
                for (i=0;i<strlen(t0);i++)
                {
                    t1[wp++]=t0[i];
                    wp%=512;
                    t1[wp]=0;
        
                    if(t0[i] == '\n')
                    {
                        wp=0;
                        if(checksum_gps(t1))
                        {
                            if(memcmp("$GPRMC",t1,6)==0)
                            {
                                unsigned int latcnt1=0, log_cnt1=0,spdcnt=0, cogcnt=0;
                                char cog[20];
                                char spd[20];
                                char lat1[20], lg1[20];
                                for(i=20;i<28;i++)
                                {
                                    lat1[latcnt1++]=t1[i];
                                }
                                float j=atof(lat1);
                                float k=(int)(j/100);
                                float minlat  = j - ( k * 100 );
                                float ddeglat = k + ( minlat / 60 );
                                ui->latitude->setText(QString::number(ddeglat,'f'));
        
                                for(i=33;i<42;i++)
                                {
                                    lg1[log_cnt1++]=t1[i];
                                }
                                float p=atof(lg1);
                                float q=(int)(p/100);
                                float minlong  = p - ( q * 100 );
                                float ddeglong = q + ( minlong / 60 );
                                ui->longitude->setText(QString::number(ddeglong,'f'));
        
                                for (i=45;i<50;i++)
                                {
                                    spd[spdcnt++]=t1[i];
                                }
                                float r=atof(spd);
                                ui->speed->setText(QString::number(r,'f',4));
        
                                for (i=50;i<56;i++)
                                {
                                    cog[cogcnt++]=t1[i];
                                }
                                float u=atof((cog));
                                float w=u*0.514444;
                                ui->cog->setText(QString::number(w,'f',4));
        
                                stream<<strcat(t1,timestamp());
                                ui->rece->setText(t1);
                                fflush(stdout);
                            }
                        }
                    }
                }
                file.close();
            }
            ui->timest->setText(timestamp());
        }
        
        void MainWindow::on_infobutton_clicked()
        {
            info = new Info(this);
            info->show();
        }
        
        void MainWindow::on_setupbutton_clicked()
        {
            setup = new Setup(this);
            setup->show();
        }
        
        //Setup.h
        
        #ifndef SETUP_H
        #define SETUP_H
        #include <mainwindow.h>
        #include <QDialog>
        
        namespace Ui {
        class Setup;
        }
        
        class Setup : public QDialog
        {
            Q_OBJECT
        
        public:
            explicit Setup(QWidget *parent = nullptr);
            ~Setup();
        
        public slots:
             void onNewSerialData(QString data);
        
        private slots:
            void serialReceived1();
            void on_start_toggled(bool checked);
        
        private:
            Ui::Setup *ui;
        };
        
        #endif // SETUP_H
        
        
        //Setup.cpp
        
        #include "setup.h"
        #include "ui_setup.h"
        #include <QSerialPort>
        #include <QDebug>
        #include <mainwindow.h>
        #include <QSerialPortInfo>
        #include <QFile>
        
        //QSerialPort *serial1;
        Setup::Setup(QWidget *parent) :
            QDialog(parent),
            ui(new Ui::Setup)
        {
            ui->setupUi(this);
            ui->start->setCheckable(true);
            connect(this, &MainWindow:: newSerialData, Setup, &Setup:: onNewSerialData);
        }
        
        void Setup::onNewSerialData(QString data)
        {
             ui->receiver->append(data);
        }
        

        Edit[j.hilk] added code tags for readability

        1 Reply Last reply
        0
        • S Offline
          S Offline
          Shivam Sharma
          wrote on last edited by
          #7

          Here there is an error in connect, says: Setup doesn't refer to a value.

          JonBJ J.HilkJ 2 Replies Last reply
          0
          • S Shivam Sharma

            Here there is an error in connect, says: Setup doesn't refer to a value.

            JonBJ Online
            JonBJ Online
            JonB
            wrote on last edited by JonB
            #8

            @Shivam-Sharma

            connect(this, &MainWindow:: newSerialData, Setup, &Setup:: onNewSerialData);

            Here there is an error in connect, says: Setup doesn't refer to a value.

            As the message states. The Setup as the 3rd parameter is a class. You need an instance (just like you have for the 1st parameter). See the docs.

            1 Reply Last reply
            0
            • S Shivam Sharma

              Here there is an error in connect, says: Setup doesn't refer to a value.

              J.HilkJ Online
              J.HilkJ Online
              J.Hilk
              Moderators
              wrote on last edited by J.Hilk
              #9

              @Shivam-Sharma
              I said where you create Setup, you put the connect into the constructor of Setup

              here:

              void MainWindow::on_setupbutton_clicked()
              {
                  setup = new Setup(this);
                  setup->show();
                  connect(this, &MainWindow::newSerialData, setup, &Setup::onNewSerialData);
              }
              

              but, every time you click on the setupButton you will create a new instance of that class, you're leaking memory


              Edit changed for error free connect, thanks to @JonB for mentioning it


              Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


              Q: What's that?
              A: It's blue light.
              Q: What does it do?
              A: It turns blue.

              JonBJ S 2 Replies Last reply
              3
              • J.HilkJ J.Hilk

                @Shivam-Sharma
                I said where you create Setup, you put the connect into the constructor of Setup

                here:

                void MainWindow::on_setupbutton_clicked()
                {
                    setup = new Setup(this);
                    setup->show();
                    connect(this, &MainWindow::newSerialData, setup, &Setup::onNewSerialData);
                }
                

                but, every time you click on the setupButton you will create a new instance of that class, you're leaking memory


                Edit changed for error free connect, thanks to @JonB for mentioning it

                JonBJ Online
                JonBJ Online
                JonB
                wrote on last edited by JonB
                #10

                @J-Hilk
                As per my previous, to help the user in this case you should change your 3rd param from Setup to setup anyway. Unless you want him to figure for himself (which would not be a bad idea, bit late now that I have spoken!) :)

                1 Reply Last reply
                1
                • J.HilkJ J.Hilk

                  @Shivam-Sharma
                  I said where you create Setup, you put the connect into the constructor of Setup

                  here:

                  void MainWindow::on_setupbutton_clicked()
                  {
                      setup = new Setup(this);
                      setup->show();
                      connect(this, &MainWindow::newSerialData, setup, &Setup::onNewSerialData);
                  }
                  

                  but, every time you click on the setupButton you will create a new instance of that class, you're leaking memory


                  Edit changed for error free connect, thanks to @JonB for mentioning it

                  S Offline
                  S Offline
                  Shivam Sharma
                  wrote on last edited by
                  #11

                  @J-Hilk everthing is error free except one, which I ain't undertsanding:

                  'Setup' does not name a type.

                  J.HilkJ JonBJ 2 Replies Last reply
                  0
                  • S Shivam Sharma

                    @J-Hilk everthing is error free except one, which I ain't undertsanding:

                    'Setup' does not name a type.

                    J.HilkJ Online
                    J.HilkJ Online
                    J.Hilk
                    Moderators
                    wrote on last edited by J.Hilk
                    #12

                    @Shivam-Sharma
                    where ?
                    It should point you to a line


                    actually, remove the mainwindow.h include from setup
                    here

                    #include "setup.h"
                    #include "ui_setup.h"
                    #include <QSerialPort>
                    #include <QDebug>
                    #include <mainwindow.h>
                    #include <QSerialPortInfo>
                    #include <QFile>
                    

                    and here

                    #ifndef SETUP_H
                    #define SETUP_H
                    #include <mainwindow.h>
                    #include <QDialog>
                    

                    thats a circular include with your mainwindow.h were you include setup.h


                    Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                    Q: What's that?
                    A: It's blue light.
                    Q: What does it do?
                    A: It turns blue.

                    1 Reply Last reply
                    3
                    • S Shivam Sharma

                      @J-Hilk everthing is error free except one, which I ain't undertsanding:

                      'Setup' does not name a type.

                      JonBJ Online
                      JonBJ Online
                      JonB
                      wrote on last edited by JonB
                      #13

                      @Shivam-Sharma
                      As @J-Hilk has said. And further to that: (unless a Qt expert contradicts me) you should never be including mainwindow.h into anything other than mainwindow.cpp and your main.cpp, not into any other UI stuff you define. Keeps it clean --- they should never need to know about your MainWindow class. This is true all over the place: a widget which accesses/opens a "child" widget should include that child's .h file, but the "child" widgets should never need to know about/include the .h file of other ("parent") widgets where they might be called from. At least usually.

                      1 Reply Last reply
                      2
                      • S Offline
                        S Offline
                        Shivam Sharma
                        wrote on last edited by
                        #14
                        This post is deleted!
                        1 Reply Last reply
                        0
                        • S Offline
                          S Offline
                          Shivam Sharma
                          wrote on last edited by
                          #15

                          @J-Hilk @JonB

                          Thank you so much guys. This really helped me. All the solutions that you'll constantly engaged me with really means a lot. Appreciate this.

                          1 Reply Last reply
                          2
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #16

                            Hi,

                            One small addition, when passing QString around like that (but it is also valid for other classes), it's a good habit to use const references. This allows to avoid creating unneeded copies.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            1 Reply Last reply
                            2
                            • S Offline
                              S Offline
                              Shivam Sharma
                              wrote on last edited by
                              #17

                              @J-Hilk @JonB Hi guys. Need one more help. If i want to add a push button on the Setup form that connects and disconnects the serial data incoming on both the forms how could I do that.

                              This is the code for the push button, i can do it on the mainwindow form but unable to do it on the Setup form since it is not being able to access *serial.

                              Code:

                              void MainWindow::on_start_toggled(bool checked)
                              {
                                  ui->start->setText(ui->start->isChecked() ? "Connect" : "Disconnect");
                                  if (checked)
                                  {
                                      serial->close();
                                      ui->start->setStyleSheet(QString("QPushButton {background-color: rgb(115, 210, 22);}"));
                                  }
                                  else
                                  {
                                      ui->start->setStyleSheet(QString("QPushButton {background-color: red;}"));
                              
                              
                                         serial = new QSerialPort(this);
                                         serial = new QSerialPort(this);
                                         serial->setPortName("ttyUSB0");
                                         serial->setBaudRate(QSerialPort::Baud9600);
                                         serial->setDataBits(QSerialPort::Data8);
                                         serial->setParity(QSerialPort::NoParity);
                                         serial->setStopBits(QSerialPort::OneStop);
                                         serial->setFlowControl(QSerialPort::NoFlowControl);
                              
                                         if( serial->open(QIODevice::ReadWrite))
                                          {
                                              qDebug()<<"Port Open OK";
                                              connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
                                          }
                                        else
                                          {
                                              qDebug()<<"Can't Open Port : " << serial->error();
                                          }
                                         serialReceived();
                                  }
                              }
                              
                              jsulmJ 1 Reply Last reply
                              0
                              • S Shivam Sharma

                                @J-Hilk @JonB Hi guys. Need one more help. If i want to add a push button on the Setup form that connects and disconnects the serial data incoming on both the forms how could I do that.

                                This is the code for the push button, i can do it on the mainwindow form but unable to do it on the Setup form since it is not being able to access *serial.

                                Code:

                                void MainWindow::on_start_toggled(bool checked)
                                {
                                    ui->start->setText(ui->start->isChecked() ? "Connect" : "Disconnect");
                                    if (checked)
                                    {
                                        serial->close();
                                        ui->start->setStyleSheet(QString("QPushButton {background-color: rgb(115, 210, 22);}"));
                                    }
                                    else
                                    {
                                        ui->start->setStyleSheet(QString("QPushButton {background-color: red;}"));
                                
                                
                                           serial = new QSerialPort(this);
                                           serial = new QSerialPort(this);
                                           serial->setPortName("ttyUSB0");
                                           serial->setBaudRate(QSerialPort::Baud9600);
                                           serial->setDataBits(QSerialPort::Data8);
                                           serial->setParity(QSerialPort::NoParity);
                                           serial->setStopBits(QSerialPort::OneStop);
                                           serial->setFlowControl(QSerialPort::NoFlowControl);
                                
                                           if( serial->open(QIODevice::ReadWrite))
                                            {
                                                qDebug()<<"Port Open OK";
                                                connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
                                            }
                                          else
                                            {
                                                qDebug()<<"Can't Open Port : " << serial->error();
                                            }
                                           serialReceived();
                                    }
                                }
                                
                                jsulmJ Offline
                                jsulmJ Offline
                                jsulm
                                Lifetime Qt Champion
                                wrote on last edited by
                                #18

                                @Shivam-Sharma Create a signal in Setup, connect that signal to clicked() signal of the button in Setup and then connect the signal you created in Setup (the first one I mentioned) to a slot in MainWindow where you can enable/disable the serial port.

                                https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                • S Offline
                                  S Offline
                                  Shivam Sharma
                                  wrote on last edited by
                                  #19

                                  I am sorry, but unable to understand. How do i connect the pushbutton to mainwindow from Setup form, since i cannot inherit the parent class, neither can i create an instance of it. Could you give a demo?

                                  jsulmJ 1 Reply Last reply
                                  0
                                  • S Shivam Sharma

                                    I am sorry, but unable to understand. How do i connect the pushbutton to mainwindow from Setup form, since i cannot inherit the parent class, neither can i create an instance of it. Could you give a demo?

                                    jsulmJ Offline
                                    jsulmJ Offline
                                    jsulm
                                    Lifetime Qt Champion
                                    wrote on last edited by jsulm
                                    #20

                                    @Shivam-Sharma said in Is data received from serial port possible to view on two forms?:

                                    How do i connect the pushbutton to mainwindow from Setup form

                                    You don't, please read more carefully.

                                    class Setup
                                    {
                                    signals:
                                        void onOffSerialPort();
                                    };
                                    
                                    void Setup::Setup()
                                    {
                                        connect(ui->button, &QPushButton::clicked, this, &Setup::onOffSerialButton);
                                    }
                                    
                                    // MainWindow
                                    connect(setup, &Setup::onOffSerialButton, this, &MainWindow::onOffSerialButton);
                                    

                                    As you can see Setup does not know anything about MainWindow.

                                    https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                    • S Offline
                                      S Offline
                                      Shivam Sharma
                                      wrote on last edited by
                                      #21
                                      // MainWindow
                                      connect(setup, &Setup::onOffSerialButton, this, &MainWindow::onOffSerialButton);
                                      
                                      

                                      shouldn't all of this be

                                      onOffSerialPort
                                      

                                      and the last part be :

                                      &MainWindow::close);
                                      
                                      void Mainwindow::close()
                                      {
                                      serial->close();
                                      }
                                      jsulmJ 1 Reply Last reply
                                      0
                                      • S Shivam Sharma
                                        // MainWindow
                                        connect(setup, &Setup::onOffSerialButton, this, &MainWindow::onOffSerialButton);
                                        
                                        

                                        shouldn't all of this be

                                        onOffSerialPort
                                        

                                        and the last part be :

                                        &MainWindow::close);
                                        
                                        void Mainwindow::close()
                                        {
                                        serial->close();
                                        }
                                        jsulmJ Offline
                                        jsulmJ Offline
                                        jsulm
                                        Lifetime Qt Champion
                                        wrote on last edited by
                                        #22

                                        @Shivam-Sharma Sorry, I don't understand what you mean. The code I provided is just to show the idea, you need to adapt it to your needs.

                                        https://forum.qt.io/topic/113070/qt-code-of-conduct

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                                        • J.HilkJ Online
                                          J.HilkJ Online
                                          J.Hilk
                                          Moderators
                                          wrote on last edited by J.Hilk
                                          #23

                                          let me expand on @jsulm example

                                          first of in your mainwindow, create a new function, defined as a slot

                                          and copy the content of your on button clicked in there

                                          public slots:
                                               void toggleSerial(bool checked);
                                          
                                          //mainwindow.cpp
                                          void MainWindow:: toggleSerial(bool checked)
                                          {
                                                ui->start->setText(ui->start->isChecked() ? "Connect" : "Disconnect");
                                                    if (checked)
                                                    {
                                                        serial->close();
                                                        ui->start->setStyleSheet(QString("QPushButton {background-color: rgb(115, 210, 22);}"));
                                                    }
                                                    else
                                                    {
                                                        ui->start->setStyleSheet(QString("QPushButton {background-color: red;}"));
                                                
                                                
                                                           serial = new QSerialPort(this);
                                                           serial = new QSerialPort(this);
                                                           serial->setPortName("ttyUSB0");
                                                           serial->setBaudRate(QSerialPort::Baud9600);
                                                           serial->setDataBits(QSerialPort::Data8);
                                                           serial->setParity(QSerialPort::NoParity);
                                                           serial->setStopBits(QSerialPort::OneStop);
                                                           serial->setFlowControl(QSerialPort::NoFlowControl);
                                                
                                                           if( serial->open(QIODevice::ReadWrite))
                                                            {
                                                                qDebug()<<"Port Open OK";
                                                                connect(serial, &QSerialPort::readyRead, this, &MainWindow::serialReceived);
                                                            }
                                                          else
                                                            {
                                                                qDebug()<<"Can't Open Port : " << serial->error();
                                                            }
                                                           serialReceived();
                                                    }
                                          }
                                          void MainWindow::on_start_toggled(bool checked)
                                          {
                                              toggleSerial(checked);
                                          }
                                          

                                          inside Setup add the signal like @jsulm suggested

                                          signals:
                                              void onOffSerialPort(bool checked);
                                          

                                          connect your button toggle signal (in Setup) to this signal (constructor of Setup

                                          connect(ui->myButton, &QPushButton:: toggled, this, &Setup:: onOffSerialPort);
                                          

                                          and finally
                                          connect that onOffSerialPort signal to your toggleSerial slot

                                          connect(setup, &Setup:: onOffSerialPort, this, &MainWindow:: toggleSerial);
                                          

                                          one thing to keep in mind, your 2 buttons will now not necessarily show the correct checked status.

                                          I'll let you figure that one out.


                                          Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                          Q: What's that?
                                          A: It's blue light.
                                          Q: What does it do?
                                          A: It turns blue.

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