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Serial data received

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qt c++serialportdatabuffer
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  • M Offline
    M Offline
    manel.sam
    wrote on last edited by manel.sam
    #9
    This post is deleted!
    1 Reply Last reply
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    • JonBJ JonB

      @manel-sam said in Serial data received:

      however I also receive data of 0 bytes, which are empty and this quite frequently

      • If you only call readAll() once in response to each readRead() signal you will never get 0 bytes.
      • If you get 0 bytes you are calling readAll() a second time/not in response to readyRead(). Find out where, and don't do it.

      I would like to receive each time the data in full form

      You cannot guarantee you will receive all bytes on any one particular readAll() call. Like @J-Hilk said you need to write code to accumulate the (potentially fragments) of data you receive.

      M Offline
      M Offline
      manel.sam
      wrote on last edited by
      #10

      Imu::~Imu()
      {
      serialPort->close();
      }

      void Imu::handleError(QSerialPort::SerialPortError error)
      {
      if (error == QSerialPort::ResourceError){
      qDebug()<<"Handle Error"<<error;
      serialPort->close();
      }
      }

      void Imu::pollSerialPort()
      {

       QByteArray d= serialPort->readAll().toHex();
      
         QByteArray hexData = d.append(serialPort->readAll().toHex());
      
      qDebug() << "Serial received " << hexData;
      

      i used it like this

      JonBJ 1 Reply Last reply
      0
      • M manel.sam

        Imu::~Imu()
        {
        serialPort->close();
        }

        void Imu::handleError(QSerialPort::SerialPortError error)
        {
        if (error == QSerialPort::ResourceError){
        qDebug()<<"Handle Error"<<error;
        serialPort->close();
        }
        }

        void Imu::pollSerialPort()
        {

         QByteArray d= serialPort->readAll().toHex();
        
           QByteArray hexData = d.append(serialPort->readAll().toHex());
        
        qDebug() << "Serial received " << hexData;
        

        i used it like this

        JonBJ Online
        JonBJ Online
        JonB
        wrote on last edited by JonB
        #11

        @manel-sam
        This is wrong because you have two calls to serialPort->readAll(). How many more times can I say you cannot afford to do this? [In fact you kind of get away with this the way you write, but why are you calling it twice??]

        M 1 Reply Last reply
        2
        • JonBJ JonB

          @manel-sam
          This is wrong because you have two calls to serialPort->readAll(). How many more times can I say you cannot afford to do this? [In fact you kind of get away with this the way you write, but why are you calling it twice??]

          M Offline
          M Offline
          manel.sam
          wrote on last edited by
          #12

          @JonB Sorry, I copied the wrong code

          I used the readAll once, but I still get the 0 Bytes

          J.HilkJ JonBJ 2 Replies Last reply
          0
          • M manel.sam

            @JonB Sorry, I copied the wrong code

            I used the readAll once, but I still get the 0 Bytes

            J.HilkJ Offline
            J.HilkJ Offline
            J.Hilk
            Moderators
            wrote on last edited by
            #13

            @manel-sam can you show more of your code, calling connect multiple times will lead to such a behaviour as well


            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.

            M 1 Reply Last reply
            0
            • J.HilkJ J.Hilk

              @manel-sam can you show more of your code, calling connect multiple times will lead to such a behaviour as well

              M Offline
              M Offline
              manel.sam
              wrote on last edited by
              #14

              @J-Hilk

              Imu::Imu() :
              moving(false)
              {

              serialPort = new QSerialPort("COM3",this);
              
              if (serialPort->open( QIODevice::ReadWrite))
              {
              
                  qDebug()<<"SerialPort"<<serialPort<<"Opened successufly";
              }
              else
              {
                  qDebug()<<serialPort->error();
                  QSerialPortInfo::availablePorts();
              }
              
              if (!serialPort->setBaudRate(57600))
                  log_error("imu","failed to set baudrate, error no %d",serialPort->error());
              serialPort->setDataBits(QSerialPort::Data8);
              serialPort->setParity(QSerialPort::NoParity);
              serialPort->setStopBits(QSerialPort::OneStop); // One Stop bit
              serialPort->setFlowControl(QSerialPort::NoFlowControl);
              qDebug()<<"error"<<serialPort->errorString();
              
              QObject::connect(this->serialPort,SIGNAL(readyRead()),this,SLOT(pollSerialPort()));
              QObject::connect(serialPort, &::QSerialPort::errorOccurred,this,&Imu::handleError);
              
              }
              

              Imu::~Imu()
              {
              serialPort->close();
              }

              void Imu::handleError(QSerialPort::SerialPortError error)
              {
              if (error == QSerialPort::ResourceError){
              qDebug()<<"Handle Error"<<error;
              serialPort->close();
              }
              }

              void Imu::pollSerialPort()
              {

              QByteArray hexData;
              hexData.append(serialPort->readAll().toHex());
              
              qDebug() << "Serial received " << hexData;
              QByteArray data = QByteArray::fromHex(hexData);
              
              // data size
              qInfo() << QStringLiteral("data size is : ") << data.size() << " octets";
              
              QDataStream stream(data);
              
              // Read The BigIndian value
              stream.setByteOrder(QDataStream::BigEndian);
              qint16 headerSignature;
              stream >> headerSignature;
              
              M 1 Reply Last reply
              0
              • M manel.sam

                @J-Hilk

                Imu::Imu() :
                moving(false)
                {

                serialPort = new QSerialPort("COM3",this);
                
                if (serialPort->open( QIODevice::ReadWrite))
                {
                
                    qDebug()<<"SerialPort"<<serialPort<<"Opened successufly";
                }
                else
                {
                    qDebug()<<serialPort->error();
                    QSerialPortInfo::availablePorts();
                }
                
                if (!serialPort->setBaudRate(57600))
                    log_error("imu","failed to set baudrate, error no %d",serialPort->error());
                serialPort->setDataBits(QSerialPort::Data8);
                serialPort->setParity(QSerialPort::NoParity);
                serialPort->setStopBits(QSerialPort::OneStop); // One Stop bit
                serialPort->setFlowControl(QSerialPort::NoFlowControl);
                qDebug()<<"error"<<serialPort->errorString();
                
                QObject::connect(this->serialPort,SIGNAL(readyRead()),this,SLOT(pollSerialPort()));
                QObject::connect(serialPort, &::QSerialPort::errorOccurred,this,&Imu::handleError);
                
                }
                

                Imu::~Imu()
                {
                serialPort->close();
                }

                void Imu::handleError(QSerialPort::SerialPortError error)
                {
                if (error == QSerialPort::ResourceError){
                qDebug()<<"Handle Error"<<error;
                serialPort->close();
                }
                }

                void Imu::pollSerialPort()
                {

                QByteArray hexData;
                hexData.append(serialPort->readAll().toHex());
                
                qDebug() << "Serial received " << hexData;
                QByteArray data = QByteArray::fromHex(hexData);
                
                // data size
                qInfo() << QStringLiteral("data size is : ") << data.size() << " octets";
                
                QDataStream stream(data);
                
                // Read The BigIndian value
                stream.setByteOrder(QDataStream::BigEndian);
                qint16 headerSignature;
                stream >> headerSignature;
                
                M Offline
                M Offline
                mpergand
                wrote on last edited by mpergand
                #15

                @manel-sam said in Serial data received:

                QByteArray hexData;
                hexData.append(serialPort->readAll().toHex());

                hexData is local, so you append nothing !

                hexData.append(serialPort->readAll().toHex());
                qDebug() << "Serial received " << hexData;
                QByteArray data = QByteArray::fromHex(hexData);

                you convert to ascii then back to binary !!??

                You must check the packet is complete (37 bytes) before processing any further.

                M 1 Reply Last reply
                3
                • M manel.sam

                  @JonB Sorry, I copied the wrong code

                  I used the readAll once, but I still get the 0 Bytes

                  JonBJ Online
                  JonBJ Online
                  JonB
                  wrote on last edited by JonB
                  #16

                  @manel-sam said in Serial data received:

                  I used the readAll once, but I still get the 0 Bytes

                  And where in your code do you now get this?

                  Separately you need to follow @mpergand's comments.

                  In handleError() you only report anything if QSerialPort::ResourceError, and silently ignore if any other error, for whatever reason. Please don't write code like this, and certainly not while developing/debugging.

                  M 1 Reply Last reply
                  0
                  • M mpergand

                    @manel-sam said in Serial data received:

                    QByteArray hexData;
                    hexData.append(serialPort->readAll().toHex());

                    hexData is local, so you append nothing !

                    hexData.append(serialPort->readAll().toHex());
                    qDebug() << "Serial received " << hexData;
                    QByteArray data = QByteArray::fromHex(hexData);

                    you convert to ascii then back to binary !!??

                    You must check the packet is complete (37 bytes) before processing any further.

                    M Offline
                    M Offline
                    manel.sam
                    wrote on last edited by manel.sam
                    #17

                    @mpergand Yes it was just to visualize the data in hexa as in the documentation of my sensor, then I preferred to work in binary.

                    So the append I should do it where§?

                    M 1 Reply Last reply
                    0
                    • M manel.sam

                      @mpergand Yes it was just to visualize the data in hexa as in the documentation of my sensor, then I preferred to work in binary.

                      So the append I should do it where§?

                      M Offline
                      M Offline
                      mpergand
                      wrote on last edited by mpergand
                      #18

                      @manel-sam said in Serial data received:

                      So the append I should do it where§?

                      Create a member variable in your imu class.

                          // _packetData  member variable of imu
                          _packetData.append(serialPort->readAll());
                          
                          if(_packetData.size()>=PACKET_LENGTH)
                              {
                              // packet complete
                              qInfo() << QStringLiteral("data size is : ") << _packetData.size() << " octets";
                              qDebug() << "Serial received " << _packetData.toHex();
                              
                              // go ahead with this packet
                              QDataStream stream(_packetData);
                              
                              // Read The BigIndian value
                              stream.setByteOrder(QDataStream::BigEndian);
                              qint16 headerSignature;
                              stream >> headerSignature;
                              }
                      

                      You may also check the data received don't exceed PACKET_LENGTH, cause it means you have already received data from the next packet. (it may be irrelevant in your case, I don't kown)

                      1 Reply Last reply
                      0
                      • JonBJ JonB

                        @manel-sam said in Serial data received:

                        I used the readAll once, but I still get the 0 Bytes

                        And where in your code do you now get this?

                        Separately you need to follow @mpergand's comments.

                        In handleError() you only report anything if QSerialPort::ResourceError, and silently ignore if any other error, for whatever reason. Please don't write code like this, and certainly not while developing/debugging.

                        M Offline
                        M Offline
                        manel.sam
                        wrote on last edited by manel.sam
                        #19
                        This post is deleted!
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