SerialPort QT C data sensor-CodePudding

I am writing a program to collect data from an IMU sensor through a SerialPort

The data of the IMU received via the software of the latter are in Hexadecimal

So I would like to extract them in Hexadecimal too in a first time

You will find attached my program, the problem is that I receive 0 at each data reception.

static const int FRAME_SIZE = 68;

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

    serialPort = new QSerialPort("COM3",this);
    if (!serialPort->open( QIODevice::ReadOnly))
    {
        log_warning("imu","failed to open device file \"%s\", IMU measures will be unavailable",qPrintable(serialPort->portName()));
        return;
    }

    if (!serialPort->setBaudRate(115200))
        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);

    pollingTimer = new QTimer(this);
    QObject::connect(pollingTimer, SIGNAL(timeout()), this, SLOT(pollSerialPort()));
    pollingTimer->start(10);

    }

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

void Imu::pollSerialPort()
{
    static const unsigned char START_BYTES[2] = {0x55,0xAA};
    static const QByteArray START_WORD((char*)START_BYTES,2);

    static QTime startTime = QTime::currentTime();
    static QByteArray data;
    data.append(serialPort->readAll());
    qDebug() << data.count() << data.toHex();

CodePudding user response：

Define two slots in your Imu class, one to read data and another to handle error condition, then connected them to errorOccurred and readyRead signals of QSerialPort like this.

serialPort = new QSerialPort("COM3",this);
connect(serialPort, &QSerialPort::errorOccurred, this, &Imu::handleError);
connect(serialPort, &QSerialPort::readyRead, this, &Imu::readData);

When data arrives on serial port, Qt will automatically call readData slots. In readData you can get all the data like this

void Imu::readData() {
    const QByteArray data = serialPort->readAll();
    qDebug() << data.count() << data.toHex();
}

In handleError function, you can check different error conditions:

void Imu::handleError(QSerialPort::SerialPortError error)
{
    if (error == QSerialPort::ResourceError) {
        // handle error
    }
}

Side Note: Don't use old style signal/slot connection, use new style. Below link provides nice explanation.

https://wiki.qt.io/New_Signal_Slot_Syntax

CodePudding user response：

Thank you for your answer,

I have done the readyread, however this time, I had no data reception. Not even the 0 that I had at the beginning.

Thanks again for your reply.

QObject::connect(serialPort, &QSerialPort::errorOccurred, this, &Imu::handleError);
QObject::connect(serialPort, &QSerialPort::readyRead, this, &Imu::pollSerialPort);


}

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

void Imu::handleError(QSerialPort::SerialPortError error)
{
    if (error == QSerialPort::ResourceError) {
   // qDebug()<<"handleerror" <<;
    }
}


void Imu::pollSerialPort()
{
    static const unsigned char START_BYTES[2] = {0x55,0xAA};
    static const QByteArray START_WORD((char*)START_BYTES,2);
    static QTime startTime = QTime::currentTime();
    if (!pollingTimer->isActive()){
            pollingTimer->start(10);
    }
    static QByteArray data;
    data.append(serialPort->readAll());
    qDebug() << data.count() << data.toHex();