how to check data package received in serial port is 5 byte and check each byte ?

[suhairkp]

Hello all,
i want to process output from a serial device , which sending 5 bytes of data serially with 4800 BR and odd parity. i read data serially and displayed in text edit. Now i want to check the received data package is 5 Byte and 7th bit of 1st byte is high and store second byte in QByte array .



Qt code :

ui->setupUi(this);
    QVector<double> data_x(101), data_y(101);
    timer.start();
    init_port();
    init_line_plot();
 
    x_position = 0;
 
    connect(serial, SIGNAL(readyRead()), this, SLOT(receive()));
}
 
MainWindow::~MainWindow()
{
    delete ui;
    serial->close();
}
void MainWindow::init_port()
{
    QTextStream out(stdout);
    QString portname = "/dev/ttyUSB0";
    serial = new QSerialPort(portname);
    if (!serial->open(QIODevice::ReadWrite))
    {
        QMessageBox::warning(this, "port error", "cannot open port");
    }
 
    serial->setBaudRate(QSerialPort::Baud4800);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->setParity(QSerialPort::OddParity);
    serial->setDataBits(QSerialPort::Data8);
    serial->setStopBits(QSerialPort::OneStop);
    out <<"port opened"<<endl<<endl;
}
 
void MainWindow::init_line_plot()
{
            ui->customPlot->addGraph();
            ui->customPlot->xAxis->setLabel("t");
            ui->customPlot->yAxis->setLabel("V");
}
 
void MainWindow::receive()
{
    // recieves data as ASCII string
   int datalength = 1000;
   char data [1000];
   int bytesRead = serial->readLine(data, datalength);
    data[bytesRead]='\0';
 
    ui->textEdit->append(QString(data));
 
    QTextStream out(stdout);
    out << data << endl;
    addDataPoint(atof(data));
}
 
void MainWindow::addDataPoint(double datapoint)
{
    if (x_position>250)data_x.pop_front();
    double ms = timer.elapsed();
    data_x.push_back((double)ms/1000);
    x_position++;
    if (x_position>250) data_y.pop_front();
    data_y.push_back(datapoint);
 
 
           ui->customPlot->graph(0)->setData(data_x,data_y);
           ui->customPlot->setBackground(Qt::black);
           ui->customPlot->graph(0)->rescaleAxes();
           ui->customPlot->replot();
 
}

ui->setupUi(this);
    QVector<double> data_x(101), data_y(101);
    timer.start();
    init_port();
    init_line_plot();

    x_position = 0;

    connect(serial, SIGNAL(readyRead()), this, SLOT(receive()));
}

MainWindow::~MainWindow()
{
    delete ui;
    serial->close();
}
void MainWindow::init_port()
{
    QTextStream out(stdout);
    QString portname = "/dev/ttyUSB0";
    serial = new QSerialPort(portname);
    if (!serial->open(QIODevice::ReadWrite))
    {
        QMessageBox::warning(this, "port error", "cannot open port");
    }

    serial->setBaudRate(QSerialPort::Baud4800);
    serial->setFlowControl(QSerialPort::NoFlowControl);
    serial->setParity(QSerialPort::OddParity);
    serial->setDataBits(QSerialPort::Data8);
    serial->setStopBits(QSerialPort::OneStop);
    out <<"port opened"<<endl<<endl;
}

void MainWindow::init_line_plot()
{
            ui->customPlot->addGraph();
            ui->customPlot->xAxis->setLabel("t");
            ui->customPlot->yAxis->setLabel("V");
}

void MainWindow::receive()
{
    // recieves data as ASCII string
   int datalength = 1000;
   char data [1000];
   int bytesRead = serial->readLine(data, datalength);
    data[bytesRead]='\0';

    ui->textEdit->append(QString(data));

    QTextStream out(stdout);
    out << data << endl;
    addDataPoint(atof(data));
}

void MainWindow::addDataPoint(double datapoint)
{
    if (x_position>250)data_x.pop_front();
    double ms = timer.elapsed();
    data_x.push_back((double)ms/1000);
    x_position++;
    if (x_position>250) data_y.pop_front();
    data_y.push_back(datapoint);


           ui->customPlot->graph(0)->setData(data_x,data_y);
           ui->customPlot->setBackground(Qt::black);
           ui->customPlot->graph(0)->rescaleAxes();
           ui->customPlot->replot();

}

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Anyone please help me ....

[high_flyer]

Anyone please help me ....

Gladly, just tell us what the problem or question is, then we might help you...

[ado130]

Not sure if I understand, but you can use static_cast the first byte to uint, and then mask 7th bit.

[Lesiok]

First of all : in line 47 (serial->readLine()...) You can get any number of bytes in the range of <1..1000>.
Before atof() you need to check whether the buffer contains a complete package.