如何在Qt Creator中采集外部串行设备的实时数据？

Question

我正在尝试从arduino收集实时数据(使用Qt类QSerialPort)，并将其实时绘制为图形(使用类QCustomPlot)。我是使用串行设备的新手，所以我不太确定在QSerialPort类中使用哪个函数来收集数据。下面是我设置序列号的当前代码：

QSerialPort serial;

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    serial.setPortName("com4");
    serial.setBaudRate(QSerialPort::Baud9600);
    serial.setDataBits(QSerialPort::Data8);
    serial.setParity(QSerialPort::NoParity);
    serial.setStopBits(QSerialPort::OneStop);
    serial.setFlowControl(QSerialPort::NoFlowControl);
    serial.open(QIODevice::ReadWrite);

    setupRealtimeDataDemo(ui->customPlot);


}

...and这里是我的实时时隙数据的代码...

void MainWindow::realtimeDataSlot()
{
  // calculate two new data points:
#if QT_VERSION < QT_VERSION_CHECK(4, 7, 0)
  double key = 0;
#else
  double key = QDateTime::currentDateTime().toMSecsSinceEpoch()/1000.0;
#endif
  static double lastPointKey = 0;
  if (key-lastPointKey > 0.01) // at most add point every 10 ms
  {
    double value0 = qSin(key); //sin(key*1.6+cos(key*1.7)*2)*10 + sin(key*1.2+0.56)*20 + 26;
    double value1 = qCos(key); //sin(key*1.3+cos(key*1.2)*1.2)*7 + sin(key*0.9+0.26)*24 + 26;
    // add data to lines:
    ui->customPlot->graph(0)->addData(key, value0);
    ui->customPlot->graph(1)->addData(key, value1);
    // set data of dots:
    ui->customPlot->graph(2)->clearData();
    ui->customPlot->graph(2)->addData(key, value0);
    ui->customPlot->graph(3)->clearData();
    ui->customPlot->graph(3)->addData(key, value1);
    // remove data of lines that's outside visible range:
    ui->customPlot->graph(0)->removeDataBefore(key-8);
    ui->customPlot->graph(1)->removeDataBefore(key-8);
    // rescale value (vertical) axis to fit the current data:
    ui->customPlot->graph(0)->rescaleValueAxis();
    ui->customPlot->graph(1)->rescaleValueAxis(true);
    lastPointKey = key;
  }
  // make key axis range scroll with the data (at a constant range size of 8):
  ui->customPlot->xAxis->setRange(key+0.25, 8, Qt::AlignRight);
  ui->customPlot->replot();

  // calculate frames per second:
  static double lastFpsKey;
  static int frameCount;
  ++frameCount;
  if (key-lastFpsKey > 2) // average fps over 2 seconds
  {
    ui->statusBar->showMessage(
          QString("%1 FPS, Total Data points: %2")
          .arg(frameCount/(key-lastFpsKey), 0, 'f', 0)
          .arg(ui->customPlot->graph(0)->data()->count()+ui->customPlot->graph(1)->data()->count())
          , 0);
    lastFpsKey = key;
    frameCount = 0;
  }
}

任何关于如何实时获取数据和/或更好的实现的帮助都将不胜感激。谢谢:)

Answer 1

您可以将QSerialPort的readyRead信号连接到插槽，以便在新数据到达时读取数据：

connect(serial, SIGNAL(readyRead()), this, SLOT(readData()));

在readData中，您可以调用readAll()将所有可用数据读取到QByteArray，并将数组传递给另一个函数进行绘图：

void MainWindow::readData()
{
    QByteArray data = serial->readAll();

    plotMyData(data);
}

Answer 2

I wrote a full demo application，它显示了如何从串口读取数据。

• 指定打开有效连接所需的设置，在本例中为Arduino device;
• 实现负责读取数据并将其打印到控制台的类。

对于某些设备(如Arduino)，在open()成功后调用setDataTerminalReady(true);是必不可少的。因此，对于那些在使用Terminal Example时遇到问题的人，请记住将void MainWindow::openSerialPort()修改为：

void MainWindow::openSerialPort()
{
    SettingsDialog::Settings p = settings->settings();
    serial->setPortName(p.name);
    serial->setBaudRate(p.baudRate);
    serial->setDataBits(p.dataBits);
    serial->setParity(p.parity);
    serial->setStopBits(p.stopBits);
    serial->setFlowControl(p.flowControl);
    if (serial->open(QIODevice::ReadWrite)) {
            console->setEnabled(true);
            console->setLocalEchoEnabled(p.localEchoEnabled);
            ui->actionConnect->setEnabled(false);
            ui->actionDisconnect->setEnabled(true);
            ui->actionConfigure->setEnabled(false);
            ui->statusBar->showMessage(tr("Connected to %1 : %2, %3, %4, %5, %6")
                                       .arg(p.name).arg(p.stringBaudRate).arg(p.stringDataBits)
                                       .arg(p.stringParity).arg(p.stringStopBits).arg(p.stringFlowControl));

            // HACK
            serial->setDataTerminalReady(true);
    } else {
        QMessageBox::critical(this, tr("Error"), serial->errorString());

        ui->statusBar->showMessage(tr("Open error"));
    }
}