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    Solved Qt Serial port Not Receive data until send data to mc.

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    • M
      Marco Flad last edited by aha_1980

      i used the blockingslave Example to Ensure the Micro Controller send data and received it correct without any missing in data i mean " if any input pin on micro controller status changes from low to high and vs versa send data over serial port to QT"
      my problem the readyrad() signal doesn't emitted until i send any data to micro controller from qt and by the way i send data to micro controller suspenseful without no error or missing.

      //mainwindow.h
      #ifndef MAINWINDOW_H
      #define MAINWINDOW_H
      #include <QMainWindow>
      #include <QtDebug>
      
      QT_BEGIN_NAMESPACE
      namespace Ui { class MainWindow; }
      QT_END_NAMESPACE
      class QSerialPort ;
      class MainWindow : public QMainWindow
      {
          Q_OBJECT
      
      public:
          MainWindow(QWidget *parent = nullptr);
          ~MainWindow();
      private slots:
      
      private:
          Ui::MainWindow *ui;
          //Serial
          QSerialPort *mc;
          //for Rs232 Cable NotArduino
          static const quint16 arduino_uno_vendor_id  =  1367;   //9025 ; 
          static const quint16 arduino_uno_product_id =  8200;   //67   ; 
          QString mc_port_name;
          bool mc_is_available;
      };
      #endif // MAINWINDOW_H
      

      //mainwindow.cpp
      
      #include "mainwindow.h"
      #include "ui_mainwindow.h"
      #include <QSerialPort>
      #include <QSerialPortInfo>
      
          ui->setupUi(this);
         QMainWindow::showFullScreen();
      
          //********************************************DoSerialAutoConnect***********************************************//
          //**************************************************************************************************************//
      
      MainWindow::MainWindow(QWidget *parent)
          : QMainWindow(parent )  //, Qt::FramelessWindowHint
          , ui(new Ui::MainWindow)
      {
          mc_is_available = false;
          mc_port_name = "";
          mc = new QSerialPort(this);
      
      
          qDebug() << "Number of available ports: " << QSerialPortInfo::availablePorts().length();
          foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts()){
              qDebug() << "Has vendor ID: " << serialPortInfo.hasVendorIdentifier();
              if(serialPortInfo.hasVendorIdentifier()){
                  qDebug() << "Vendor ID: " << serialPortInfo.vendorIdentifier();
              }
              qDebug() << "Has Product ID: " << serialPortInfo.hasProductIdentifier();
              if(serialPortInfo.hasProductIdentifier()){
                  qDebug() << "Product ID: " << serialPortInfo.productIdentifier();
              }
          }
      
      
          foreach(const QSerialPortInfo &serialPortInfo, QSerialPortInfo::availablePorts()){
              if(serialPortInfo.hasVendorIdentifier() && serialPortInfo.hasProductIdentifier()){
                  if(serialPortInfo.vendorIdentifier() == arduino_uno_vendor_id){
                      if(serialPortInfo.productIdentifier() == arduino_uno_product_id){
                          mc_port_name = serialPortInfo.portName();
                          mc_is_available = true;
                      }
                  }
              }
          }
      
          if(mc_is_available){
              // open and configure the serialport
              mc->setPortName(mc_port_name);   //QString("COM8")
              mc->open(QIODevice::ReadWrite);
              mc->setBaudRate(QSerialPort::Baud9600);
              mc->setDataBits(QSerialPort::Data8);
              mc->setParity(QSerialPort::NoParity);
              mc->setStopBits(QSerialPort::OneStop);
              mc->setFlowControl(QSerialPort::NoFlowControl);
      
              connect(mc, SIGNAL(readyRead()), this, SLOT(updateReceivedData()));
          }else{
              // give error message if not available
              QMessageBox::warning(this, "Port error", "Couldn't find the Arduino!");
          }
      }
      
      MainWindow::~MainWindow()
      {
          delete ui;
          if(mc->isOpen()){
              mc->close();
          }
      }
      
      
      void MainWindow::updateReceivedData()
      {
          // qDebug("received data\n");
          // arduino->waitForReadyRead(100);
      
          inBuffer = mc->readAll();
          while (mc->waitForReadyRead(10))
              inBuffer += mc->readAll();
          qDebug() << inBuffer;
      
      

      please any help ;

      SGaist 1 Reply Last reply Reply Quote 0
      • K
        kuzulis Qt Champions 2020 last edited by kuzulis

        Are you sure that you use Qt 5.14.0? Maybe you use Qt 5.13.1? Please check it again and again.

        PS: As I see that you use Qt 5.13.1 && MinGW, according to your another post (with mutex).

        M 1 Reply Last reply Reply Quote 3
        • Christian Ehrlicher
          Christian Ehrlicher Lifetime Qt Champion last edited by

          What Qt version do you use? There were some problems with 5.12.x (@aha_1980: you know better) with the readyRead() signal.

          Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
          Visit the Qt Academy at https://academy.qt.io/catalog

          M 1 Reply Last reply Reply Quote 2
          • M
            Marco Flad @Christian Ehrlicher last edited by

            @Christian-Ehrlicher said in Qt Serial port Not Receve data until send data to mc.:

            12
            iam using Qt 5.14.0 (MSVC 2017, 32 bit)
            thanks for replay

            1 Reply Last reply Reply Quote 0
            • SGaist
              SGaist Lifetime Qt Champion @Marco Flad last edited by

              Hi,

              @Marco-Flad said in Qt Serial port Not Receve data until send data to mc.:

              // open and configure the serialport
              mc->setPortName(mc_port_name); //QString("COM8")
              mc->open(QIODevice::ReadWrite);
              mc->setBaudRate(QSerialPort::Baud9600);
              mc->setDataBits(QSerialPort::Data8);
              mc->setParity(QSerialPort::NoParity);
              mc->setStopBits(QSerialPort::OneStop);
              mc->setFlowControl(QSerialPort::NoFlowControl);

              Two things:

              • Do the complete setup before calling open
              • Check the return value of open, it might have failed and you don't check that case.

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

              M 1 Reply Last reply Reply Quote 1
              • M
                Marco Flad @SGaist last edited by

                @SGaist
                i move open to down and checked if is isOpen() .
                Everything that can return Boolean returns a true state and without errors.
                the strange problem is
                if i send any number of messages from micro controller this messages stored in buffer and not appear until readyread() is emitted
                and readyread() not emitted until i send data to the micro controller i.e when i call arduino->write (" ");
                the hilighted is one message the three messages is sent from micro controller in different times but appears in debugger when i send data to micro controller .
                alt text

                aha_1980 1 Reply Last reply Reply Quote 0
                • aha_1980
                  aha_1980 Lifetime Qt Champion @Marco Flad last edited by

                  Hi @Marco-Flad,

                  my problem the readyrad() signal doesn't emitted until i send any data to micro controller

                  May it be that your microcontroller is exactly programmed like that? It does not seem unusual to me.

                  Anyway, you should first try the communication with a terminal program to ensure everything is working correctly before programming yourself.

                  Afterwards, you should try and study the Terminal example, you can get it from the examples section in Qt Creator.

                  And then you can come back to your own code.

                  Regards

                  Qt has to stay free or it will die.

                  M 1 Reply Last reply Reply Quote 0
                  • M
                    Marco Flad @aha_1980 last edited by

                    @aha_1980 said in Qt Serial port Not Receive data until send data to mc.:

                    your

                    Hi ,
                    iam sorry but i try Terminal program isn't work but PuTTY work well and blockingslave serial example work very well also in send and recive so i think the only way to use thriding like blocking slave example .

                    1 Reply Last reply Reply Quote 0
                    • K
                      kuzulis Qt Champions 2020 last edited by kuzulis

                      Are you sure that you use Qt 5.14.0? Maybe you use Qt 5.13.1? Please check it again and again.

                      PS: As I see that you use Qt 5.13.1 && MinGW, according to your another post (with mutex).

                      M 1 Reply Last reply Reply Quote 3
                      • M
                        Marco Flad @kuzulis last edited by

                        @kuzulis
                        hi ,
                        ya you are right iam using C:\Qt\5.13.1 i notice it after locking in setting
                        but in (Help about Qt creator ) Based on 5.14.0 and
                        alt text
                        and in Manage kit only 5.13.1 so ho to update version
                        f6f564ed-6251-477f-b7ce-d5a8383e68cd-image.png image url)
                        thank you ,

                        aha_1980 1 Reply Last reply Reply Quote 0
                        • aha_1980
                          aha_1980 Lifetime Qt Champion @Marco Flad last edited by

                          Hi @Marco-Flad,

                          your Qt Creator is build with Qt 5.14, but your kit is using Qt 5.13 - that explains your problems.

                          You can update your installation with the MaintenanceTool in c:\Qt. I'd recommend to uninstall Qt 5.13.1 so you do not accidently use it again.

                          Regards

                          Qt has to stay free or it will die.

                          M 1 Reply Last reply Reply Quote 4
                          • M
                            Marco Flad @aha_1980 last edited by

                            @aha_1980 thanks Very match its all about version
                            @kuzulis thanks for your support
                            my pleasures.

                            1 Reply Last reply Reply Quote 1
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