QSerialPort - Reading cut

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QSerialPort - Reading cut

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#1 by (1 votes)
#2 by (-1 votes)

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I am having problems to read whole lines from the serial port in linux. I have a gps that connects to the serial port and I can not get the lines read from it to arrive complete. I put the code that I have (taken from the Terminal Example Example of QT.) In that example, they send what they receive to a QPlainTextEdit, and they show the QPlainTextEdit so they are "pretty" the output ... but I need the complete line to process it Here is my code (it is worth clarifying that the new is done in another part of the code):

void MainWindow::openSerialPort()
{
    m_serial->setPortName("/dev/ttyUSB0");
    m_serial->setBaudRate(9600);
    connect(m_serial, &QSerialPort::readyRead, this, &MainWindow::readData);

    if (m_serial->open(QIODevice::Read)) {
        qDebug() << "Conectado Correctamente!";
    } else {
        qDebug() << "Error al conectar!";
    }
}

void MainWindow::readData()
{
    const QByteArray data = m_serial->readAll();
    qDebug() << data << endl;
}

And the output obtained is as follows:

Connected Properly!
  "DAA, -61.262786, -37.245445,587.6,0.1,288.6,40718,20505200,7 \ r \ n00,7 \ r \ nDATA, -61.262786, -37.245445,587.3,0.1,288.6,40718,20505000,7 \ r \ nDATA, -61.262786, -37.245445,587.6,0.1,288.6,40718,20505200,7 \ r \ n "

"St"

"arti"

"ng"

"to p"

"rubbing"

"ss .."

". \ r \ n"

"DAT"

"A, -6"

"1.26"

"2798"

", - 3"

"7.24"

"5452"

", 58"

"7.9,"

"0.5,"

"0.0,"

"4071"

"8,20"

"505"

"700.7 \ r \ n"

"DATA"

", - 61"

When in fact, I expected to obtain the same as the output of the Terminal example program that is shown below:

DATA,-61.262786,-37.245445,587.3,0.1,288.6,40718,20505000,7
DATA,-61.262786,-37.245445,587.6,0.1,288.6,40718,20505200,7

c++ qt

asked by Emiliano Torres 04.07.2018 в 22:55

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2 answers

-1

Googling a bit I came to the following solution:

void MainWindow::readData()
{
    while (m_serial->canReadLine()) 
        qInfo() << m_serial->readLine();
}

With those simple lines, we have in the buffer the complete line that arrives from the serial port. From what I understand, the serial port would be the one that does the buffering until the line is complete and just there you can do the readLine. To me, these lines solved a big problem.

answered by 05.07.2018 в 18:42

Filter an Outputtext jsf get a value of a function in javascript and send it to php to make a query in mysql

score 1 · Accepted Answer

What seems to be happening is that readData is invoked on numerous occasions and on each occasion it contains only a fragment of the data ... you would have to prepare the reading routine to concatenate the successive readings and then that separates by line breaks:

void MainWindow::readData()
{
  static QString buffer;

  buffer += m_serial->readAll();

  while( int pos = buffer.indexOf("\r") != -1 )
  {
    qDebug() << buffer.left(pos);
    buffer = buffer.mid(pos+2);
  }
}