Serial data received

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.

manel.sam

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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

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??]

manel.sam

@JonB Sorry, I copied the wrong code

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

J.Hilk

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

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;

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.

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.

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§?

mpergand

@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)

manel.sam

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